CN109357728B - Microstrip double-branch directional coupler and radar level measurement system - Google Patents
Microstrip double-branch directional coupler and radar level measurement system Download PDFInfo
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- CN109357728B CN109357728B CN201811222931.0A CN201811222931A CN109357728B CN 109357728 B CN109357728 B CN 109357728B CN 201811222931 A CN201811222931 A CN 201811222931A CN 109357728 B CN109357728 B CN 109357728B
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- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
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Abstract
A radar level gauging system is disclosed. The radar level gauging system comprises: the device comprises a radar signal transceiver, a microstrip branch line directional coupler and a transceiver antenna; the radar signal receiving and transmitting device comprises a transmitting channel group and a receiving channel group; the microstrip branch line directional coupler includes four port leads: an input port lead, a pass-through port lead, a coupled port lead and an isolated port lead; the input port lead is connected with the transmitting channels in the transmitting channel group; the isolation port lead is connected with a first receiving channel in the receiving channel group; the through port lead or the coupling port lead is connected with the receiving and transmitting antenna; the coupling port lead or the through port lead which is not connected with the transceiving antenna on the microstrip branch line directional coupler is connected with other receiving channels except the first receiving channel in the receiving channel group. The method can solve the impedance matching problem of the vacant port of the microstrip branch line directional coupler, thereby improving the measurement accuracy of the radar level measurement system.
Description
Technical Field
The invention relates to the technical field of level measurement, in particular to a microstrip double-branch directional coupler and a radar level measurement system.
Background
Radar level gauges use the special properties of electromagnetic waves for level sensing. Electromagnetic waves can penetrate through space steam, dust and other interference sources, and are easy to reflect when encountering obstacles. Transmit-reflect-receive is the basic principle of operation of radar level gauges. The antenna of the radar sensor emits electromagnetic wave signals in the form of beams, and the reflected signals are still received by the antenna. The time of travel of the electromagnetic wave signal from transmission to reception is proportional to the distance of the sensor from the surface of the medium.
As shown in fig. 1, in the field of radar level measurement, a single antenna is often used to transmit and receive electromagnetic wave signals due to limitations in structure, installation, sealing, explosion prevention, and the like. In the radar level gauge shown in FIG. 1, a single antenna 32 is used for transmitting and receiving electromagnetic wave signals, and a single chip radar sensor 30 may achieve isolation of a transmitting channel and a receiving channel by means of a directional coupler 31.
The branch line directional coupler is a common couplerAnd a directional coupler. As shown in fig. 2, a 3dB microstrip dual-branch directional coupler is composed of a main line, a sub line and two coupled branch lines. AB is a main line, DC is a secondary line, AD and BC are branch lines, the length and the interval of the two branch lines are quarter wavelength (lambda/4), and the characteristic impedance of the AB main line and the DC secondary line are all
The characteristic impedance of the AD branch line and the BC branch line is z0Characteristic impedance of each port is z0. When the port (1) has input and other ports are matched, the port (2) and the port (3) have equal-amplitude out-of-phase output, 90-degree phase difference exists between the port (2) and the port (3), no signal is output from the port (4), and the port (4) is an isolated port. The 3dB microstrip double-branch directional coupler has good symmetry, and any one port of the four ports can be used as an input port.
With the continuous increase of the frequency of electromagnetic waves, when the radar level gauge develops from a centimeter wave band to a millimeter wave band, the isolation of the directional coupler is reduced due to the fact that the size of the 3dB microstrip double-branch directional coupler is reduced, and the measurement accuracy of the radar level gauge is affected.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a radar level measuring system, which can improve the measuring precision of the radar level measuring system.
According to an aspect of the present application, an embodiment of the present invention provides a radar level gauging system, comprising: a radar signal transceiving device 100, a microstrip branch line directional coupler 200, and a transceiving antenna 300; the radar signal transceiving apparatus 100 includes a transmit channel group 110 and a receive channel group 120; the microstrip branch line directional coupler 200 includes four port leads: input port lead 51, through port lead 61, coupled port lead 71 and isolated port lead 81;
the input port lead 51 is connected with the transmitting channels in the transmitting channel group 110;
the isolated port lead 81 is connected to a first receive channel in the set of receive channels 120;
the through port lead 61 or the coupling port lead 71 is connected with the transceiving antenna 300;
a coupling port lead 71 or a through port lead 61 of the microstrip branch line directional coupler 200, which is not connected to the transceiving antenna 300, is connected to the other receiving channels except the first receiving channel in the receiving channel group 120.
According to another aspect of the present application, an embodiment of the present invention provides a radar level gauging system, comprising: a radar signal transceiver device 100, a microstrip branch line directional coupler 200, a transceiver antenna 300 and a power absorption device 600; the radar signal transceiving apparatus 100 includes a transmit channel group 110 and a receive channel group 120; the microstrip branch line directional coupler 200 includes four port leads: input port lead 51, through port lead 61, coupled port lead 71 and isolated port lead 81;
the input port lead 51 is connected with the transmitting channels in the transmitting channel group 110;
the isolated port lead 81 is connected to a receive channel in the receive channel group 120;
the through port lead 61 or the coupling port lead 71 is connected with the transceiving antenna 300;
a coupling port lead 71 or a through port lead 61, which is not connected with the transceiving antenna 300, on the microstrip branch line directional coupler 200 is connected with the power absorption device 600;
the power absorbing device 600 includes: a microstrip patch antenna 601 and a wave-absorbing material 602 covering the microstrip patch antenna 601.
Compared with the related art, according to the radar level measurement system provided by the embodiment of the invention, the vacant port (the coupling port or the through port which is not connected with the receiving and transmitting antenna) in the microstrip branch line directional coupler is connected to other receiving channels of the radar signal receiving and transmitting device, so that the problem of impedance matching of the vacant port of the microstrip branch line directional coupler is solved, and the measurement accuracy of the radar level measurement system is improved.
Compared with the prior art, the radar level measurement system provided by the embodiment of the invention can solve the problem of impedance matching of the vacant port of the microstrip branch line directional coupler by connecting the vacant port (the through port or the coupling port which is not connected with the transmitting-receiving antenna) in the microstrip branch line directional coupler to the microstrip patch antenna covered with the wave-absorbing material, thereby improving the measurement accuracy of the radar level measurement system.
Drawings
FIG. 1 is a schematic view of a prior art single antenna radar level gauge;
FIG. 2 is a schematic diagram of a 3dB microstrip dual-branch directional coupler according to the prior art;
fig. 3 is a schematic diagram of a circular microstrip double-branch directional coupler according to embodiment 1 of the present invention;
fig. 4-a is a schematic diagram of a circular microstrip double-branch directional coupler having a branch microstrip line in embodiment 1 of the present invention;
fig. 4-b is a schematic diagram of a circular microstrip double-branch directional coupler having two branch microstrip lines in embodiment 1 of the present invention;
FIG. 5 is a schematic diagram of a port lead in embodiment 1 of the present invention;
FIG. 6 is a schematic view of a radar level gauging system according to embodiment 2 of the present invention;
FIG. 7 is a schematic view of a radar level gauging system according to embodiment 3 of the present invention;
FIG. 8 is a schematic view of a radar level gauging system according to example 1 of the present invention;
FIG. 9 is a diagram illustrating the results of HFSS testing of a circular microstrip dual-branch directional coupler according to example 1 of the present invention;
FIG. 10 is a schematic view of a radar level gauging system according to example 2 of the present invention;
fig. 11 is a schematic diagram illustrating HFSS test results of a circular microstrip dual-branch directional coupler with a branched microstrip line according to example 2 of the present invention;
FIG. 12 is a schematic view of a radar level gauging system according to example 3 of the present invention;
fig. 13 is a schematic diagram illustrating HFSS test results of a circular microstrip dual-branch directional coupler with two branched microstrip lines according to example 3 of the present invention;
FIG. 14 is a schematic view of a radar level gauging system according to example 4 of the present invention;
FIG. 15 is a schematic view of another radar level gauging system according to example 4 of the present invention.
Reference numerals
1 main line; 2 a first branch line; 3, secondary lines; 4 second branch line;
5, an input port; 6 a straight-through port; 7 a coupling port; 8 isolating the port;
51 input port lead; 61 through port lead; 71 coupling port leads; 81 isolating the port lead;
30 a single chip radar sensor; 31 a directional coupler; 32 antennas;
11 a first microstrip line; 12 a second microstrip line; 13 a third microstrip line;
21 a first stub microstrip line; 22 a second stub microstrip line;
100 radar signal transceiver means; 200 microstrip branch line directional coupler; 300 a transceiver antenna;
a 400 power combiner; 500 power dividers;
110 transmit channel groups; 120 receiving a channel group;
1101 a first transmit channel; 1102 a second transmit channel; 1201 a first receive channel; 1202 a second receive channel; 1203 a third receive channel;
600 power absorbing means; 601 a microstrip patch antenna; 602 a wave-absorbing material;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
The use of "first," "second," and similar terms in the description and claims of this application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
Example 1
As shown in fig. 3, an embodiment of the present invention provides a microstrip dual-branch directional coupler, including: the system comprises a main line 1, a first branch line 2, a secondary line 3, a second branch line 4, four ports and four port lead wires;
the four ports include: an input port 5 located at the junction of the main line 1 and the second branch line 4, a pass-through port 6 located at the junction of the main line 1 and the first branch line 2, a coupling port 7 located at the junction of the first branch line 2 and the secondary line 3, and an isolation port 8 located at the junction of the secondary line 3 and the second branch line 4;
the four port leads include: an input port lead 51 disposed on said input port 5, a through port lead 61 disposed on said through port 6, a coupling port lead 71 disposed on said coupling port 7 and an isolation port lead 81 disposed on said isolation port 8;
the main line 1, the first branch line 2, the secondary line 3 and the second branch line 4 are sequentially connected end to form a closed ring; the lengths of the main line 1, the first branch line 2, the auxiliary line 3 and the second branch line 4 are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip double-branch directional coupler;
the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring.
In the above embodiment, the input port lead and the isolation port lead are not parallel wires any longer, but are wires at a certain angle, so that the distance between the input signal channel and the output signal channel is increased, the mutual interference between the input signal and the output signal is reduced, and the isolation of the directional coupler is improved.
In one embodiment, the closed loop comprises: circular, or elliptical. Compared with the prior art, the microstrip double-branch directional coupler provided by the embodiment of the invention has the advantages that by adopting the annular microstrip double-branch directional coupler, the input port lead and the isolation port lead are not parallel but form an included angle, so that the distance between an input signal channel and an output signal channel is increased, the mutual interference between an input signal and an output signal is reduced, and the isolation degree of the directional coupler is improved.
In one embodiment, the microstrip dual branch directional coupler further comprises:
one or more stub microstrip lines provided on the input port lead 51, the through port lead 61, or the coupling port lead 71;
in one embodiment, stub microstrip lines disposed on port leads are perpendicular to the port leads;
as shown in fig. 4-a, the microstrip dual-branch directional coupler includes: and the first stub microstrip line 21, wherein the first stub microstrip line 21 is arranged on the input port lead 51. In other embodiments, the number of microstrip lines provided on the same port lead may be multiple.
In one embodiment, the microstrip dual branch directional coupler further comprises:
a first stub microstrip line 21 provided on the input port lead 51 and a second stub microstrip line 22 provided on the through port lead 61; or
A first stub microstrip line 21 provided on the input port lead 51 and a second stub microstrip line 22 provided on the coupling port lead 71;
a first stub microstrip line 21 disposed on the through port lead 61 and a second stub microstrip line 22 disposed on the coupling port lead 71;
as shown in fig. 4-b, the microstrip dual-branch directional coupler includes: a first stub microstrip line 21 and a second stub microstrip line 22; the first stub microstrip line 21 is disposed on the input port lead 51, and the second stub microstrip line 22 is disposed on the coupled port lead 71. In other embodiments, the number of microstrip lines provided on the same port lead may be multiple.
In one embodiment, the length of the stub microstrip line disposed on the port lead may be λ/4, and the distance between the stub microstrip line and the port corresponding to the port lead may be λ/4.
In the above embodiment, after one or more ports are added with the stub microstrip line, a part of the input signal is reflected back to the isolation port through the stub microstrip line, and the reflected signal meets the transmission signal leaked from the input port to the isolation port, and the transmission signal can form power cancellation, so that the leakage output of the transmission signal from the input port from the isolation port is reduced, and the isolation degree of the directional coupler is improved.
In one embodiment, the characteristic impedances of the main line 1 and the secondary line 2 of the microstrip double-branch directional coupler are both
The characteristic impedance of the first branch line 3 and the second branch line 4 is z0(ii) a The microstrip double-branch directional coupler is a directional coupler with a coupling coefficient of 3dB and has good symmetry.
Z is less than or equal to the frequency threshold when the center frequency of the microstrip double-branch directional coupler is less than or equal to the frequency threshold0Is 50 ohms; z is greater than the frequency threshold when the center frequency of the microstrip double-branch directional coupler is greater than the frequency threshold0Greater than 50 ohms.
Wherein the frequency threshold may be set to 20 GHz. For example, when the center frequency of the microstrip double-branch directional coupler is 78GHz, z is0Can be set to 100 ohms;
in one embodiment, as shown in fig. 5, the port lead comprises: characteristic impedance of z0Has a characteristic impedance of
And a characteristic impedance z of the second microstrip line 121The third microstrip line 13; a first end of the first microstrip line 11 is connected to the port, a second end of the first microstrip line 11 is connected to a first end of the second microstrip line 12, and a second end of the second microstrip line 12 is connected to a second end of the third microstrip line 13The first end is connected; wherein z is0Greater than z1. For example, when the center frequency of the microstrip double-branch directional coupler is greater than 20GHz, z is0Is 100 ohm, z1Is 50 ohms.
In one embodiment, when the port lead includes the first microstrip line 11, the second microstrip line 12, and the third microstrip line 13 described above, the stub microstrip line provided on the port lead is provided on the first microstrip line 11;
in one embodiment, the port lead comprises: a characteristic impedance from z0Is gradually changed into z1The impedance gradual change microstrip line; wherein the characteristic impedance of the impedance gradient microstrip line close to the port is z0The characteristic impedance away from the port is z1(ii) a Wherein z is0Greater than z1. For example, when the center frequency of the microstrip double-branch directional coupler is greater than 20GHz, z is0Is 100 ohm, z1Is 50 ohms.
Example 2
As shown in FIG. 6, an embodiment of the present invention provides a radar level gauging system, comprising: a radar signal transceiving device 100, a microstrip branch line directional coupler 200, and a transceiving antenna 300; the radar signal transceiving apparatus 100 includes a transmit channel group 110 and a receive channel group 120;
the microstrip branch line directional coupler 200 includes four port leads: input port lead 51, through port lead 61, coupled port lead 71 and isolated port lead 81;
the input port lead 51 is connected with the transmitting channels in the transmitting channel group 110;
the isolated port lead 81 is connected to a first receive channel in the set of receive channels 120;
the through port lead 61 or the coupling port lead 71 is connected with the transceiving antenna 300;
a coupling port lead 71 or a through port lead 61 of the microstrip branch line directional coupler 200, which is not connected to the transceiving antenna 300, is connected to the other receiving channels except the first receiving channel in the receiving channel group 120.
With the increase of the frequency of the electromagnetic wave (millimeter wave), it is difficult to find an existing device as a load to implement port matching of the directional coupler, so that in the above embodiment, the vacant port (the coupling port or the through port that is not connected to the transmitting and receiving antenna) in the microstrip branch line directional coupler is connected to another receiving channel of the radar signal transmitting and receiving device, thereby solving the problem of impedance matching of the vacant port of the microstrip branch line directional coupler and improving the measurement accuracy of the radar level measurement system.
Wherein the transmit channel group 110 comprises at least one transmit channel; the receive channel group 120 includes at least two receive channels;
in one embodiment, the input port lead 51 is connected to the transmit channels in the transmit channel group 110 by: the input port lead 51 is directly connected with one transmitting channel in the transmitting channel group 110; alternatively, the input port lead 51 is connected to a plurality of transmission channels in the transmission channel group 110 through a power combiner 400.
In one embodiment, the coupling port lead 71 or the through port lead 61 of the microstrip branch line directional coupler 200, which is not connected to the transceiving antenna 300, is connected to the other receiving channels of the receiving channel group 120 except the first receiving channel in the following manner: a coupling port lead 71 or a through port lead 61 of the microstrip branch line directional coupler 200, which is not connected to the transceiving antenna 300, is directly connected to one receiving channel of the receiving channel group 120 except the first receiving channel; or, the coupling port lead 71 or the through port lead 61, which is not connected to the transceiving antenna 300, of the microstrip branch line directional coupler 200 is connected to the plurality of receiving channels, except for the first receiving channel, of the receiving channel group 120 through the power splitter 500;
in one embodiment, the microstrip branch line directional coupler 200 may adopt the microstrip double branch directional coupler in the above embodiment 1. In other embodiments, the microstrip branch line directional coupler may also be a microstrip double branch directional coupler of the prior art.
In one embodiment, the transceiving antenna 300 comprises: microstrip patch antenna.
Example 3
As shown in FIG. 7, an embodiment of the present invention provides a radar level gauging system, comprising: a radar signal transceiver device 100, a microstrip branch line directional coupler 200, a transceiver antenna 300 and a power absorption device 600; the radar signal transceiving apparatus 100 includes a transmit channel group 110 and a receive channel group 120;
the microstrip branch line directional coupler 200 includes four port leads: input port lead 51, through port lead 61, coupled port lead 71 and isolated port lead 81;
the input port lead 51 is connected with the transmitting channels in the transmitting channel group 110;
the isolated port lead 81 is connected to a receive channel in the receive channel group 120;
the through port lead 61 or the coupling port lead 71 is connected with the transceiving antenna 300;
a coupling port lead 71 or a through port lead 61, which is not connected with the transceiving antenna 300, on the microstrip branch line directional coupler 200 is connected with the power absorption device 600;
the power absorbing device 600 includes: a microstrip patch antenna 601 and a wave-absorbing material 602 covering the microstrip patch antenna 601.
In the above embodiment, a special power absorption device 600 is provided, the power absorption device 600 radiates energy to the outside through the microstrip patch antenna 601, and the wave-absorbing material 602 can absorb the energy radiated to the outside by the microstrip patch antenna 601. The through port or the coupling port of the microstrip branch line directional coupler 200, which is not connected with the transceiving antenna 300, is connected to the power absorption device 600, so that the problem of impedance matching of the vacant port of the microstrip branch line directional coupler can be solved, and the measurement accuracy of the radar level measurement system is improved.
Wherein the transmit channel group 110 comprises at least one transmit channel; the receive channel group 120 includes at least one receive channel;
the input port lead 51 is connected to the transmitting channels in the transmitting channel group 110 in the following manner:
the input port lead 51 is directly connected with one transmitting channel in the transmitting channel group 110; alternatively, the first and second electrodes may be,
the input port lead 51 is connected to a plurality of transmit channels in the transmit channel group 110 through a power combiner 400.
In one embodiment, the microstrip patch antenna 601 includes: a single microstrip patch antenna, or a microstrip series-fed standing wave array;
in one embodiment, the microstrip branch line directional coupler 200 may adopt the microstrip double branch directional coupler in the above embodiment 1. In other embodiments, the microstrip branch line directional coupler may also be a microstrip double branch directional coupler of the prior art.
In one embodiment, the transceiver antenna 300 may be a microstrip patch antenna.
The microstrip dual-branch directional coupler and the radar level gauging system of the present application are described below by way of a number of examples.
Example 1
As shown in FIG. 8, the present example provides a radar level gauging system for a 78GHz radar signal source, comprising: radar signal transceiving apparatus 100, microstrip branch line directional coupler 200, and transceiving antenna 300.
The radar signal transceiving device 100 comprises a transmitting channel group 110 and a receiving channel group 120, wherein the transmitting channel group 110 at least comprises a first transmitting channel 1101; the group of receive channels comprises at least a first receive channel 1201 and a second receive channel 1202;
the microstrip branch line directional coupler 200 includes: the system comprises a main line 1, a first branch line 2, a secondary line 3, a second branch line 4, four ports and four port lead wires;
the four ports include: an input port 5 located at the junction of the main line 1 and the second branch line 4, a pass-through port 6 located at the junction of the main line 1 and the first branch line 2, a coupling port 7 located at the junction of the first branch line 2 and the secondary line 3, and an isolation port 8 located at the junction of the secondary line 3 and the second branch line 4;
the four port leads include: an input port lead 51 disposed on said input port 5, a through port lead 61 disposed on said through port 6, a coupling port lead 71 disposed on said coupling port 7 and an isolation port lead 81 disposed on said isolation port 8;
the main line 1, the first branch line 2, the secondary line 3 and the second branch line 4 are sequentially connected end to form a closed ring; the lengths of the main line 1, the first branch line 2, the auxiliary line 3 and the second branch line 4 are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip double-branch directional coupler; the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring. When the radar signal source is 78GHz, the wavelength lambda of the central frequency of the microstrip double-branch directional coupler is about 3.85mm, and the lambda/4 is about 0.96 mm.
The characteristic impedance of the main line 1 and the auxiliary line 2 of the microstrip double-branch directional coupler are both
The characteristic impedance of the first branch line 3 and the second branch line 4 is z0，z0Is 100 ohms.
Each port lead includes: characteristic impedance of z0Has a characteristic impedance of
And a characteristic impedance z of the second microstrip line 121The third microstrip line 13; a first end of the first microstrip line 11 is connected to the port, a second end of the first microstrip line 11 is connected to a first end of the second microstrip line 12, a second end of the second microstrip line 12 is connected to a first end of the third microstrip line 13, and z is a positive integer1Is 50 ohms.
The input port lead 51 is connected with the first transmission channel 1101; the isolated port lead 81 is connected to the first receiving channel 1201; the through port lead 61 is connected to the transceiver antenna 300 and the coupled port lead 71 is connected to the second receiving channel 1202. The transceiver antenna 300 is a microstrip patch antenna.
As shown in fig. 9, by performing HFSS (High Frequency Structure Simulator) test on the circular microstrip dual-branch directional coupler, the test result near the center Frequency (78.9957GHz) can be obtained as follows:
S41＝-25.7371dB；S11＝-25.2708dB；S31＝-3.5506dB；S21＝-3.9361dB
therefore, the energy leakage of the input port input signal into the isolated port measured at the isolated port is-25.7371 dB, i.e., the reverse transmission coefficient from the input port to the isolated port is-25.7371 dB. The energy reflected back to the input port by the signal input at the input port measured at the input port is-25.2708 dB, i.e. the reverse transmission coefficient from the input port to the input port is-25.2708 dB. The energy transmitted to the coupled port by the signal inputted from the input port measured at the coupled port is-3.5506 dB, that is, the reverse transmission coefficient from the input port to the coupled port is-3.5506 dB. The energy transmitted to the through port by the signal input from the input port measured at the through port is-3.9361 dB, that is, the reverse transmission coefficient from the input port to the through port is-3.9361 dB. According to the results of the HFSS test, it can be shown that the isolation around the center frequency can be improved by using the circular microstrip dual-branch directional coupler.
With the increase of the frequency of the electromagnetic wave (millimeter wave), it is difficult to find an existing device as a load to realize matching of the coupling port of the directional coupler, and therefore, the present example skillfully solves the port impedance matching problem of the microstrip branch line directional coupler 200 by connecting the coupling port to another receiving channel (second receiving channel) of the radar signal transceiving apparatus 100. On the other hand, by adopting the circular microstrip double-branch directional coupler, the input port lead and the isolation port lead are not parallel wires any more but are right-angled wires, so that the distance between an input signal channel and an output signal channel is increased, the mutual interference between an input signal and an output signal is reduced, and the isolation of the directional coupler is improved.
Example 2
As shown in FIG. 10, the present example provides a radar level gauging system for a 78GHz radar signal source, comprising: radar signal transceiving apparatus 100, microstrip branch line directional coupler 200, and transceiving antenna 300.
The radar signal transceiving device 100 comprises a transmitting channel group 110 and a receiving channel group 120, wherein the transmitting channel group 110 at least comprises a first transmitting channel 1101; the group of receive channels comprises at least a first receive channel 1201 and a second receive channel 1202;
the microstrip branch line directional coupler 200 includes: the microstrip line comprises a main line 1, a first branch line 2, a secondary line 3, a second branch line 4, four ports, four port leads and a first branch microstrip line 21;
the four ports include: an input port 5 located at the junction of the main line 1 and the second branch line 4, a pass-through port 6 located at the junction of the main line 1 and the first branch line 2, a coupling port 7 located at the junction of the first branch line 2 and the secondary line 3, and an isolation port 8 located at the junction of the secondary line 3 and the second branch line 4;
the four port leads include: an input port lead 51 disposed on said input port 5, a through port lead 61 disposed on said through port 6, a coupling port lead 71 disposed on said coupling port 7 and an isolation port lead 81 disposed on said isolation port 8;
the main line 1, the first branch line 2, the secondary line 3 and the second branch line 4 are sequentially connected end to form a closed ring; the lengths of the main line 1, the first branch line 2, the auxiliary line 3 and the second branch line 4 are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip double-branch directional coupler; the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring. When the radar signal source is 78GHz, the wavelength lambda of the central frequency of the microstrip double-branch directional coupler is about 3.85mm, and the lambda/4 is about 0.96 mm.
The characteristic impedance of the main line 1 and the auxiliary line 2 of the microstrip double-branch directional coupler are both
The characteristic impedance of the first branch line 3 and the second branch line 4 is z0，z0Is 100 ohms.
Each port lead includes: characteristic impedance of z0Has a characteristic impedance of
And a characteristic impedance z of the second microstrip line 121The third microstrip line 13; a first end of the first microstrip line 11 is connected to the port, a second end of the first microstrip line 11 is connected to a first end of the second microstrip line 12, a second end of the second microstrip line 12 is connected to a first end of the third microstrip line 13, and z is a positive integer1Is 50 ohms.
The first stub microstrip line 21 is disposed on the input port lead 51. In fact, the first microstrip minor line 21 is disposed on the first microstrip line 11 of the input port lead 51, and the first microstrip minor line 21 is perpendicular to the first microstrip line 11.
The input port lead 51 is connected with the first transmission channel 1101; the isolated port lead 81 is connected to the first receiving channel 1201; the through port lead 61 is connected to the transceiver antenna 300 and the coupled port lead 71 is connected to the second receiving channel 1202. The transceiver antenna 300 is a microstrip patch antenna.
As shown in fig. 11, by performing HFSS (High Frequency Structure Simulator) test on the circular microstrip dual-branch directional coupler, the test result near the center Frequency (78.8928GHz) can be obtained as follows:
S41＝-30.2597dB；S11＝-29.8601dB；S31＝-3.7089dB；S21＝-3.7939dB
therefore, the energy leakage of the input port input signal into the isolated port measured at the isolated port is-30.2597 dB, i.e., the reverse transmission coefficient from the input port to the isolated port is-30.2597 dB. The energy reflected back to the input port by the signal input at the input port measured at the input port is-29.8601 dB, i.e. the reverse transmission coefficient from the input port to the input port is-29.8601 dB. The energy transmitted to the coupled port by the signal inputted from the input port measured at the coupled port is-3.7089 dB, that is, the reverse transmission coefficient from the input port to the coupled port is-3.7089 dB. The energy transmitted to the through port by the signal input from the input port measured at the through port is-3.7939 dB, that is, the reverse transmission coefficient from the input port to the through port is-3.7939 dB. According to the results of the HFSS test, it can be shown that the isolation around the center frequency can be improved by using the circular microstrip dual-branch directional coupler.
With the increase of the frequency of the electromagnetic wave (millimeter wave), it is difficult to find an existing device as a load to realize matching of the coupling port of the directional coupler, and therefore, the present example skillfully solves the port impedance matching problem of the microstrip branch line directional coupler 200 by connecting the coupling port to another receiving channel (second receiving channel) of the radar signal transceiving apparatus 100. On the other hand, by adopting the circular microstrip double-branch directional coupler, the input port lead and the isolation port lead are not parallel wires any more but are right-angled wires, so that the distance between an input signal channel and an output signal channel is increased, the mutual interference between an input signal and an output signal is reduced, and the isolation of the directional coupler is improved. And after the branch microstrip line is added on the input port, a part of input signals are reflected back to the isolation port through the branch microstrip line, the reflected signals meet the transmitting signals leaked from the input port to the isolation port, power cancellation can be formed between the reflected signals and the transmitting signals, the leakage output of the transmitting signals of the input port from the isolation port is reduced, and therefore the isolation degree of the directional coupler is further improved.
Example 3
As shown in FIG. 12, the present example provides a radar level gauging system for a 78GHz radar signal source, comprising: radar signal transceiving apparatus 100, microstrip branch line directional coupler 200, and transceiving antenna 300.
The radar signal transceiving device 100 comprises a transmitting channel group 110 and a receiving channel group 120, wherein the transmitting channel group 110 at least comprises a first transmitting channel 1101 and a second transmitting channel 1102; the group of receive channels comprises at least a first receive channel 1201 and a second receive channel 1202;
the microstrip branch line directional coupler 200 includes: the microstrip line comprises a main line 1, a first branch line 2, a secondary line 3, a second branch line 4, four ports, four port leads, a first stub microstrip line 21 and a second stub microstrip line 22;
the four ports include: an input port 5 located at the junction of the main line 1 and the second branch line 4, a pass-through port 6 located at the junction of the main line 1 and the first branch line 2, a coupling port 7 located at the junction of the first branch line 2 and the secondary line 3, and an isolation port 8 located at the junction of the secondary line 3 and the second branch line 4;
the four port leads include: an input port lead 51 disposed on said input port 5, a through port lead 61 disposed on said through port 6, a coupling port lead 71 disposed on said coupling port 7 and an isolation port lead 81 disposed on said isolation port 8;
the main line 1, the first branch line 2, the secondary line 3 and the second branch line 4 are sequentially connected end to form a closed ring; the lengths of the main line 1, the first branch line 2, the auxiliary line 3 and the second branch line 4 are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip double-branch directional coupler; the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring. When the radar signal source is 78GHz, the wavelength lambda of the central frequency of the microstrip double-branch directional coupler is about 3.85mm, and the lambda/4 is about 0.96 mm.
The characteristic impedance of the main line 1 and the auxiliary line 2 of the microstrip double-branch directional coupler are both
The characteristic impedance of the first branch line 3 and the second branch line 4 is z0，z0Is 100 ohms.
Each port lead includes: characteristic impedance of z0Has a characteristic impedance of
And a characteristic impedance z of the second microstrip line 121The third microstrip line 13; a first end of the first microstrip line 11 is connected to the port, a second end of the first microstrip line 11 is connected to a first end of the second microstrip line 12, a second end of the second microstrip line 12 is connected to a first end of the third microstrip line 13, and z is a positive integer1Is 50 ohms.
The first stub microstrip line 21 is arranged on the input port lead 51; in fact, the first microstrip minor line 21 is disposed on the first microstrip line 11 of the input port lead 51, and the first microstrip minor line 21 is perpendicular to the first microstrip line 11 of the input port lead 51.
The second stub microstrip 22 is disposed on the coupling port lead 71. In fact, the second microstrip minor 22 is disposed on the first microstrip 11 of the coupled port lead 71, and the second microstrip minor 22 is perpendicular to the first microstrip 11 of the coupled port lead 71.
The input port lead 51 is connected to the first transmitting channel 1101 and the second transmitting channel 1102 in the transmitting channel group 110 through the power combiner 400. The through port lead 61 is connected to the transceiver antenna 300. The coupled port lead 71 is connected to the second receiving channel 1202 and the third receiving channel 1203 in the receiving channel group 120 through the power splitter 500. The isolated port lead 81 is connected to the first receiving channel 1201. The transceiver antenna 300 is a microstrip patch antenna.
As shown in fig. 13, by performing HFSS (High Frequency Structure Simulator) test on the circular microstrip dual-branch directional coupler, the test result near the center Frequency (79GHz) can be obtained as follows:
S41＝-40.7822dB；S11＝-36.7555dB；S31＝-3.6663dB；S21＝-3.8873dB
therefore, the energy leakage of the input port input signal into the isolated port measured at the isolated port is-40.7822 dB, i.e., the reverse transmission coefficient from the input port to the isolated port is-40.7822 dB. The energy reflected back to the input port by the signal input at the input port measured at the input port is-36.7555 dB, i.e. the reverse transmission coefficient from the input port to the input port is-36.7555 dB. The energy transmitted to the coupled port by the signal inputted from the input port measured at the coupled port is-3.6663 dB, that is, the reverse transmission coefficient from the input port to the coupled port is-3.6663 dB. The energy transmitted to the through port by the signal input from the input port measured at the through port is-3.8873 dB, that is, the reverse transmission coefficient from the input port to the through port is-3.8873 dB. According to the results of the HFSS test, it can be shown that the isolation around the center frequency can be improved by using the circular microstrip dual-branch directional coupler.
With the increase of the frequency of electromagnetic waves (millimeter waves), it is difficult to find an off-the-shelf device as a load to match the coupling port of the directional coupler, so this example skillfully solves the port impedance matching problem of the microstrip branch line directional coupler 200 by connecting the coupling port to the other two receiving channels (the second receiving channel and the third receiving channel) of the radar signal transceiving apparatus 100, and by receiving the signals of the coupling port through the multiple receiving channels, the received signal power of each receiving channel can be reduced, thereby reducing the electromagnetic interference between the receiving channels. On the other hand, by adopting the circular microstrip double-branch directional coupler, the input port lead and the isolation port lead are not parallel wires any more but are right-angled wires, so that the distance between an input signal channel and an output signal channel is increased, the mutual interference between an input signal and an output signal is reduced, and the isolation of the directional coupler is improved. And after the branch microstrip lines are added to the input port and the coupling port simultaneously, a part of input signals are reflected back to the isolation port through the branch microstrip lines, and the reflected signals meet the transmitting signals leaked to the isolation port from the input port, so that power cancellation can be formed between the reflected signals and the transmitting signals, the leakage output of the transmitting signals of the input port from the isolation port is reduced, and the isolation degree of the directional coupler is further improved.
Example 4
As shown in FIG. 14, the present example provides a radar level gauging system for a 78GHz radar signal source, comprising: radar signal transceiving apparatus 100, microstrip branch line directional coupler 200, transceiving antenna 300, and power absorbing apparatus 600.
The radar signal transceiving device 100 comprises a transmitting channel group 110 and a receiving channel group 120, wherein the transmitting channel group 110 at least comprises a first transmitting channel 1101; the group of receive channels comprises at least a first receive channel 1201;
the microstrip branch line directional coupler 200 includes: the microstrip line comprises a main line 1, a first branch line 2, a secondary line 3, a second branch line 4, four ports, four port leads, a first stub microstrip line 21 and a second stub microstrip line 22;
the four ports include: an input port 5 located at the junction of the main line 1 and the second branch line 4, a pass-through port 6 located at the junction of the main line 1 and the first branch line 2, a coupling port 7 located at the junction of the first branch line 2 and the secondary line 3, and an isolation port 8 located at the junction of the secondary line 3 and the second branch line 4;
the four port leads include: an input port lead 51 disposed on said input port 5, a through port lead 61 disposed on said through port 6, a coupling port lead 71 disposed on said coupling port 7 and an isolation port lead 81 disposed on said isolation port 8;
the main line 1, the first branch line 2, the secondary line 3 and the second branch line 4 are sequentially connected end to form a closed ring; the lengths of the main line 1, the first branch line 2, the auxiliary line 3 and the second branch line 4 are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip double-branch directional coupler; the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring. When the radar signal source is 78GHz, the wavelength lambda of the central frequency of the microstrip double-branch directional coupler is about 3.85mm, and the lambda/4 is about 0.96 mm.
The characteristic impedance of the main line 1 and the auxiliary line 2 of the microstrip double-branch directional coupler are both
The characteristic impedance of the first branch line 3 and the second branch line 4 is z0，z0Is 100 ohms.
Each port lead includes: characteristic impedance of z0Has a characteristic impedance of
And a characteristic impedance z of the second microstrip line 121The third microstrip line 13; a first end of the first microstrip line 11 is connected to the port, a second end of the first microstrip line 11 is connected to a first end of the second microstrip line 12, a second end of the second microstrip line 12 is connected to a first end of the third microstrip line 13, and z is a positive integer1Is 50 ohms.
The first stub microstrip line 21 is arranged on the input port lead 51; in fact, the first microstrip minor line 21 is disposed on the first microstrip line 11 of the input port lead 51, and the first microstrip minor line 21 is perpendicular to the first microstrip line 11 of the input port lead 51.
The second stub microstrip 22 is disposed on the coupling port lead 71. In fact, the second microstrip minor 22 is disposed on the first microstrip 11 of the coupled port lead 71, and the second microstrip minor 22 is perpendicular to the first microstrip 11 of the coupled port lead 71.
The input port lead 51 is connected to the first transmission channel 1101. The coupling port lead 71 is connected to the transceiving antenna 300. The through port lead 61 is connected to the power absorbing device 600. The isolated port lead 81 is connected to the first receiving channel 1201. The transceiver antenna 300 is a microstrip patch antenna.
As shown in fig. 14, the power absorbing apparatus 600 includes: the microstrip patch antenna comprises a single microstrip patch antenna and a wave-absorbing material covering the microstrip patch antenna. The wave-absorbing material can absorb the energy radiated by the microstrip patch antenna.
In another example, as shown in fig. 15, the power absorbing device 600 includes: the device comprises a micro-strip series-fed standing wave array and a wave-absorbing material covering the micro-strip series-fed standing wave array. The wave-absorbing material can absorb the energy radiated outside by the microstrip series-fed standing wave array.
With the increase of the frequency of electromagnetic waves (millimeter waves), it is difficult to find an existing device as a load to realize port matching of the directional coupler, so that in the present example, by providing a special power absorption device, a through port not occupied by the transmitting/receiving antenna in the microstrip branch line directional coupler is connected to the power absorption device, the problem of port load of the microstrip branch line directional coupler can be solved, and the measurement accuracy of the radar level measurement system is improved. On the other hand, by adopting the circular microstrip double-branch directional coupler, the input port lead and the isolation port lead are not parallel wires any more but are right-angled wires, so that the distance between an input signal channel and an output signal channel is increased, the mutual interference between an input signal and an output signal is reduced, and the isolation of the directional coupler is improved. And after the branch microstrip lines are added to the input port and the coupling port simultaneously, a part of input signals are reflected back to the isolation port through the branch microstrip lines, and the reflected signals meet the transmitting signals leaked to the isolation port from the input port, so that power cancellation can be formed between the reflected signals and the transmitting signals, the leakage output of the transmitting signals of the input port from the isolation port is reduced, and the isolation degree of the directional coupler is further improved.
It should be noted that there are many other embodiments of the present application and those skilled in the art can make various changes and modifications according to the present application without departing from the spirit and scope of the present application, and those changes and modifications should fall within the scope of the appended claims.
Claims (16)
1. A radar level gauging system, comprising:
the device comprises a radar signal transceiving device (100), a microstrip branch line directional coupler (200) and a transceiving antenna (300); the radar signal transceiving device (100) comprises a transmitting channel group (110) and a receiving channel group (120); the microstrip branch line directional coupler (200) includes four port leads: an input port lead (51), a through port lead (61), a coupled port lead (71) and an isolated port lead (81);
the input port lead (51) is connected with the transmitting channels in the transmitting channel group (110);
the isolated port lead (81) is connected with a first receiving channel in the receiving channel group (120);
-the through port lead (61) or the coupling port lead (71) is connected with the transceiving antenna (300);
and a coupling port lead (71) or a through port lead (61) which is not connected with the transceiving antenna (300) on the microstrip branch line directional coupler (200) is connected with other receiving channels except the first receiving channel in the receiving channel group (120).
2. The radar level gauging system of claim 1, wherein:
the input port lead (51) is connected with the transmitting channels in the transmitting channel group (110) in the following way:
the input port lead (51) is directly connected with one transmitting channel in the transmitting channel group (110); alternatively, the first and second electrodes may be,
the input port lead (51) is connected with a plurality of transmitting channels in the transmitting channel group (110) through a power combiner (400).
3. The radar level gauging system of claim 1, wherein:
the coupling port lead (71) or the through port lead (61) which is not connected with the transceiving antenna (300) on the microstrip branch line directional coupler (200) is connected with other receiving channels except the first receiving channel in the receiving channel group (120) in the following way:
a coupling port lead (71) or a through port lead (61) which is not connected with the transceiving antenna (300) on the microstrip branch line directional coupler (200) is directly connected with one receiving channel except the first receiving channel in the receiving channel group (120); alternatively, the first and second electrodes may be,
coupling port leads (71) or through port leads (61) which are not connected with the transceiving antennas (300) on the microstrip branch line directional coupler (200) are connected with a plurality of receiving channels except the first receiving channel in the receiving channel group (120) through a power divider (500).
4. The radar level gauging system according to claim 1, 2 or 3, wherein:
the microstrip branch line directional coupler (200) comprises: the device comprises a main line (1), a first branch line (2), a secondary line (3), a second branch line (4), four ports and four port lead wires;
the four ports include: an input port (5) located at the junction of the main line (1) and the second branch line (4), a through port (6) located at the junction of the main line (1) and the first branch line (2), a coupling port (7) located at the junction of the first branch line (2) and the secondary line (3), and an isolation port (8) located at the junction of the secondary line (3) and the second branch line (4);
the four port leads include: an input port lead (51) disposed on the input port (5), a through port lead (61) disposed on the through port (6), a coupled port lead (71) disposed on the coupled port (7), and an isolated port lead (81) disposed on the isolated port (8);
the main line (1), the first branch line (2), the secondary line (3) and the second branch line (4) are sequentially connected end to form a closed ring; the lengths of the main line (1), the first branch line (2), the auxiliary line (3) and the second branch line (4) are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip branch line directional coupler; the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring;
the closed loop includes: circular or elliptical rings.
5. The radar level gauging system of claim 4, wherein:
the microstrip branch line directional coupler further comprises:
one or more stub microstrip lines disposed on the input port lead (51), the through port lead (61), or the coupled port lead (71).
6. The radar level gauging system of claim 4, wherein:
the microstrip branch line directional coupler further comprises:
a first stub microstrip line (21) arranged on the input port lead (51) and a second stub microstrip line (22) arranged on the through port lead (61); or
A first stub microstrip line (21) arranged on the input port lead (51) and a second stub microstrip line (22) arranged on the coupling port lead (71); or
A first stub microstrip line (21) arranged on the through port lead (61) and a second stub microstrip line (22) arranged on the coupling port lead (71).
7. The radar level gauging system of claim 4, wherein:
the characteristic impedances of the main line (1) and the auxiliary line (3) of the microstrip branch line directional coupler are both
The characteristic impedance of the first branch line (2) and the second branch line (4) is z0；
Z is less than or equal to a frequency threshold when the microstrip branch line directional coupler center frequency is less than or equal to0Is 50 ohms; z is greater than the frequency threshold when the microstrip branch line directional coupler center frequency is greater than the frequency threshold0Greater than 50 ohms.
8. The radar level gauging system of claim 7, wherein:
the port lead includes: characteristic impedance of z0A first microstrip line (11) having a characteristic impedance of
And a characteristic impedance of z1A third microstrip line (13);
the first end of the first microstrip line (11) is connected with the port, the second end of the first microstrip line (11) is connected with the first end of the second microstrip line (12), and the second end of the second microstrip line (12) is connected with the first end of the third microstrip line (13); wherein z is0Greater than z1。
9. A radar level gauging system, comprising:
the device comprises a radar signal transceiving device (100), a microstrip branch line directional coupler (200), a transceiving antenna (300) and a power absorption device (600); the radar signal transceiving device (100) comprises a transmitting channel group (110) and a receiving channel group (120); the microstrip branch line directional coupler (200) includes four port leads: an input port lead (51), a through port lead (61), a coupled port lead (71) and an isolated port lead (81);
the input port lead (51) is connected with the transmitting channels in the transmitting channel group (110);
the isolated port lead (81) is connected with a receiving channel in the receiving channel group (120);
-the through port lead (61) or the coupling port lead (71) is connected with the transceiving antenna (300);
a coupling port lead (71) or a through port lead (61) which is not connected with the transceiving antenna (300) on the microstrip branch line directional coupler (200) is connected with the power absorption device (600);
the power absorbing device (600) comprises: the antenna comprises a microstrip patch antenna (601) and a wave-absorbing material (602) covering the microstrip patch antenna (601).
10. The radar level gauging system according to claim 9, wherein:
the microstrip patch antenna (601) comprises: a single microstrip patch antenna, or a microstrip series fed standing wave array.
11. The radar level gauging system according to claim 9, wherein:
the input port lead (51) is connected with the transmitting channels in the transmitting channel group (110) in the following way:
the input port lead (51) is directly connected with one transmitting channel in the transmitting channel group (110); alternatively, the first and second electrodes may be,
the input port lead (51) is connected with a plurality of transmitting channels in the transmitting channel group (110) through a power combiner (400).
12. The radar level gauging system according to claim 9, 10 or 11, wherein:
the microstrip branch line directional coupler (200) comprises: the device comprises a main line (1), a first branch line (2), a secondary line (3), a second branch line (4), four ports and four port lead wires;
the four ports include: an input port (5) located at the junction of the main line (1) and the second branch line (4), a through port (6) located at the junction of the main line (1) and the first branch line (2), a coupling port (7) located at the junction of the first branch line (2) and the secondary line (3), and an isolation port (8) located at the junction of the secondary line (3) and the second branch line (4);
the four port leads include: an input port lead (51) disposed on the input port (5), a through port lead (61) disposed on the through port (6), a coupled port lead (71) disposed on the coupled port (7), and an isolated port lead (81) disposed on the isolated port (8);
the main line (1), the first branch line (2), the secondary line (3) and the second branch line (4) are sequentially connected end to form a closed ring; the lengths of the main line (1), the first branch line (2), the auxiliary line (3) and the second branch line (4) are all lambda/4, and lambda is the wavelength at the central frequency of the microstrip branch line directional coupler; the port lead corresponding to each port is perpendicular to the tangent line of the closed ring at the port and extends outwards of the closed ring;
the closed loop includes: circular or elliptical rings.
13. The radar level gauging system of claim 12, wherein:
the microstrip branch line directional coupler further comprises:
one or more stub microstrip lines disposed on the input port lead (51), the through port lead (61), or the coupled port lead (71).
14. The radar level gauging system of claim 12, wherein:
the microstrip branch line directional coupler further comprises:
a first stub microstrip line (21) arranged on the input port lead (51) and a second stub microstrip line (22) arranged on the through port lead (61); or
A first stub microstrip line (21) arranged on the input port lead (51) and a second stub microstrip line (22) arranged on the coupling port lead (71); or
A first stub microstrip line (21) arranged on the through port lead (61) and a second stub microstrip line (22) arranged on the coupling port lead (71).
15. The radar level gauging system of claim 12, wherein:
the characteristic impedances of the main line (1) and the auxiliary line (3) of the microstrip branch line directional coupler are both
The characteristic impedance of the first branch line (2) and the second branch line (4) is z0；
When the microstrip branch line directional couplerWhen the heart frequency is less than or equal to the frequency threshold value, z0Is 50 ohms; z is greater than the frequency threshold when the microstrip branch line directional coupler center frequency is greater than the frequency threshold0Greater than 50 ohms.
16. The radar level gauging system of claim 15, wherein:
the port lead includes: characteristic impedance of z0A first microstrip line (11) having a characteristic impedance of
And a characteristic impedance of z1A third microstrip line (13);
the first end of the first microstrip line (11) is connected with the port, the second end of the first microstrip line (11) is connected with the first end of the second microstrip line (12), and the second end of the second microstrip line (12) is connected with the first end of the third microstrip line (13); wherein z is0Greater than z1。
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| PCT/CN2019/087279 WO2020077996A1 (en) | 2018-10-19 | 2019-05-16 | Microstrip double-branch directional coupler and radar level gauging system |
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| CN114050392B (en) * | 2021-08-19 | 2023-11-24 | 北京古大仪表有限公司 | Power combiner, high-frequency module and radar level gauge |
| CN115378464B (en) * | 2022-08-12 | 2023-08-15 | 江苏德是和通信科技有限公司 | Main and standby machine synthesis switching system of transmitter |
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| CN108445305B (en) * | 2018-03-13 | 2023-06-23 | 南京信息工程大学 | Electronic downtilt angle detection system and method for mobile base station antenna |
| CN109357728B (en) * | 2018-10-19 | 2021-06-04 | 北京古大仪表有限公司 | Microstrip double-branch directional coupler and radar level measurement system |
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2018
- 2018-10-19 CN CN201811222931.0A patent/CN109357728B/en active Active
- 2018-10-19 CN CN202110575985.0A patent/CN113483856A/en not_active Withdrawn
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2019
- 2019-05-16 WO PCT/CN2019/087279 patent/WO2020077996A1/en active Application Filing
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Also Published As
| Publication number | Publication date |
|---|---|
| CN109357728A (en) | 2019-02-19 |
| WO2020077996A1 (en) | 2020-04-23 |
| CN113483856A (en) | 2021-10-08 |
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