WO2024105086A1 - Highly compact transmitting device, particularly for low-power wireless sensors and even more particularly for use in iot systems - Google Patents

Abstract

A transmitting device (1, 10), particularly for low-power wireless sensors and even more particularly for use in loT systems, which comprises: - a printed circuit board (2) on which a chip (3) configured to generate an electromagnetic signal is installed, said chip (3) being connected to an antenna (4A, 4B; 40A, 40B) for emitting said signal; - a covering element (5) which covers the printed circuit board (2) in an upper region; wherein the antenna (4A, 4B; 40A, 40B) comprises a first portion (4 A; 40 A) printed on the printed circuit board (2). The transmitting device (1, 10) is characterized in that said antenna (4 A, 4B; 40 A, 40B) comprises a second portion (4B; 40B) printed on the covering element (5) so as to be positioned above the chip (3). The present invention also relates to a method for providing the transmitting device.

Description

HIGHLY COMPACT TRANSMITTING DEVICE, PARTICULARLY FOR LOW-POWER WIRELESS SENSORS AND EVEN MORE PARTICULARLY FOR USE IN IOT SYSTEMS

The present invention relates to a transmitting device provided with an antenna, particularly for low-power wireless sensors and even more particularly for use in loT systems, as well as a method for providing such device.

Nowadays, the need is increasingly felt to have available electronic transmitting or transceiving devices of small dimensions, particularly for use in loT systems (Internet of Things). loT systems, in fact, often require the use of wireless sensors (for example for pressure, temperature, or position), or other wireless devices that are small and consume little energy, which are capable of continuously monitoring one or more parameters and sending electromagnetic signals indicating the readings to remote devices.

Usually, these transmitting devices comprise a printed circuit board (PCB) on which a chip is installed that generates the electromagnetic signal to be transmitted and/or which is adapted to receive the signal. The emission and/or the reception of the signal occur through an antenna connected to the chip. The entire device is generally comprised in a small plastic housing.

Other characteristics of the transceiving devices used in loT systems are extremely low power consumption and signal transmission on sub-GHz bands.

As a simplification, the antennas used in this type of devices can be divided into two types:

- half-wave antennas (sometimes defined "electrical"), which have a length substantially equal to one half of the wavelength of the signal,

- and quarter-wave antennas (sometimes defined "magnetic"), which have a length substantially equal to one quarter of the wavelength of the signal. Quarter-wave antennas are the most widespread in this type of application, and require a “ground”, i.e. a part of the antenna connected to earth (or “electrically grounded”). The basic shape of a quarter- wave antenna is the "GP antenna" (Ground Plane Antenna), where the "ground" is constituted by four radial elements (usually defined “radials”) .

In loT applications, quarter-wave antennas are usually provided as a "trace" printed on the printed circuit board; alternatively, helical antennas and ceramic antennas are also known.

The length required for a quarter-wave antenna places a limit on the possible miniaturization of the transceiving device. For example, if we take a signal to be emitted at the frequency of 434 MHz, the wavelength is approximately 69 cm and the quarter- wave is approximately 17 cm: in this case, in order to be capable of effectively radiating the signal, in the background art, the size of the housing containing the electronics can not be less than approximately 5-10 cm.

Furthermore, a quarter-wave antenna is effective only when the dimensions of the printed circuit (electronics, battery, etc.) are such as to ensure an efficient "ground". If the transmitter and the antenna are all inside a casing of small dimensions, the lack of a ground drastically reduces the radiation efficiency and the intensity of the signal sent to the receiver to levels that are such that the reliability of the radio connection is impaired.

Half-wavelength antennas are constituted in practice by a dipole, without the need for a ground connection.

However, half-wave antennas are not necessarily simple and practical to use because they require a "balanced" output from the transmitter. Furthermore, as previously mentioned, half-wave antennas must have double the length of quarter-wave antennas and therefore miniaturization is even more fraught with difficulties.

Half- wave antennas can also be provided as a wire or a trace printed on the printed circuit board. A particular type of antenna, which can be made both as half-wave and as quarter-wave, are “patch” antennas, also known as rectangular microstrip antennas, which are constituted by a single metallic patch suspended on a ground plane and by a dielectric substrate placed between the ground plane and the metallic patch; the assembly of the antenna is generally contained in a plastic covering which protects the antenna from damage. They are used in various applications because they have a compact and light structure, a low profile, a geometry that can be shaped to fit surfaces and, lastly, they can be easily interfaced with the power supply of the signal (which can comprise power amplifiers, filters and/or dividers). The drawbacks of these antennas include medium to low efficiency (owing to the low-cost materials used), an inherently narrow operating band (owing to the resonant-type operation), and the real possibility of eliciting surface waves in the substrate, which are sources of spurious radiation.

Quarter- wave patch antennas are known, i.e. with a length equal to 1/4 of the wavelength, wherein the radiating metallic patch is short-circuited on the ground plane, like PIFA antennas (Planar Inverted F-Antenna).

To sum up, therefore, in the background art, the need is felt to develop transmitting devices of the type described above, in particular for application in loT systems, which offer reduced overall dimensions while retaining sufficient efficacy in signal emission.

The aim of the present invention is to provide a transmitting device, particularly for low-power wireless sensors and even more particularly for use in loT systems, that is capable of solving the above-mentioned problems and overcoming the above-mentioned limitations of the background art.

Within this aim, an object of the present invention is to provide a transmitting device, of the type mentioned above, that offers reduced overall dimensions while retaining sufficient efficacy in signal emission.

Another object of the invention consists of making available a transmitting device, of the type mentioned above, that is easy to implement and economically competitive.

Another object of the invention consists of providing a transmitting device, of the type mentioned above, that is highly versatile and/or offers competitive performance with respect to the background art.

Not least an object of the invention is to make available a valid alternative to the known art.

This aim and these and other objects which will become more apparent hereinafter are achieved by a transmitting device according to claim 1.

This aim and these and other objects which will become better apparent hereinafter are also achieved by a method according to claim 12.

Further characteristics and advantages of the invention will become better apparent from the description of some preferred, but not exclusive, embodiments of a transmitting device, illustrated by way of non-limiting example with the aid of the accompanying drawings wherein:

Figure 1 is a schematic perspective view of a first embodiment of the transmitting device, according to the invention, wherein the upper covering element is shown transparent in order to make the internal components visible;

Figure 2 is a plan view of the device of Figure 1, again with the covering element invisible;

Figure 3 is a cross-sectional view, taken along a central vertical plane, of the device of Figure 1;

Figure 4 is a schematic perspective view of a second embodiment of the transmitting device, according to the invention, wherein the upper covering element is shown transparent in order to make the internal components visible;

Figure 5 is a plan view of the device of Figure 4, again with the covering element invisible;

Figure 6 is a block diagram illustrating a possible particular embodiment of the electronic part of the transmitting device.

The only difference between the two embodiments illustrated (the first in Figures 1-3 and the second in Figures 4-5) is the antenna.

In the block diagram of Figure 6 the antenna indicated with the numbers 4A, 4B can be any antenna according to the invention, for example like the one illustrated in Figures 1-3 or the one illustrated in Figures 4-5.

With reference to the figures, the transmitting device, generally designated by the reference numeral 1 or 10 depending on which embodiment, is designed particularly to be part of a low-power wireless sensor, and even more particularly for use in loT systems.

The device 1, 10 is “transmitting” in the sense that it is adapted at least to emit, and optionally also to receive, an electromagnetic signal, preferably a radio signal, even more preferably a signal of sub-GHz frequency. The transmitting device can therefore optionally be a transceiving device.

The transmitting device 1, 10 comprises a printed circuit board 2 (PCB) on which at least one chip 3 configured to at least generate and emit an electromagnetic signal is installed, and this chip 3 is connected to an antenna 4 A, 4B; 40 A, 40B for emitting the signal.

The term “installed” is used to mean functionally coupled to or integrated with any known art. The at least one chip is preferably provided using a technique for producing integrated components, such as the known technique of packaging integrated components in the packaging material itself (known as “embedded component packaging”) based on the use of additive 3D technology or additive manufacturing, or, alternatively, using one or more conventional techniques for integrating the components in the substrate (carrier), such as System In Package technology.

The term “chip” means here any electronic device adapted to be installed on a PCB. There can be more than one chip 3 and they can be mutually connected to form a single electronic device for generating the signal, to which the antenna 4A, 4B; 40A, 40B is connected. For the sake of simplicity in the description and in the accompanying claims, the term “chip 3” will indicate a group of electronic components, optionally integrated in a single structure, which are adapted to generate the signal.

A particularly advantageous example of the group of electronic components is shown in the block diagram of Figure 6. In this particular and non-limiting embodiment, the at least one chip 3, here meaning in its entirety an electronic device for generating the signal, comprises a microcontroller 15 and a pulse generator 33 which is connected to such microcontroller 15. The microcontroller 15 is configured to receive at least one detection signal that represents at least one measurement value and to control the pulse generator 33 so that it generates at least one PPM signal comprising information corresponding to such at least one measurement value.

PPM signals are pulsed signals ("PPM pulses") and are per se conventional, and are the result of PPM modulation of a radiofrequency ("RF") carrier. In the case of the present invention, the RF carrier is preferably selected from one of the free bands for short-range devices, for example ISM.

The antenna 4A, 4B, which is connected to the output of the pulse generator 33, is configured for the radio transmission of the PPM signal.

Also in this particular embodiment, the pulse generator 33 comprises an oscillator 35 and a power amplifier 34 (the latter with an input connected to the oscillator 35), the function of which is to amplify the RF pulses in output from the oscillator 35 and to emit the PPM signal. Advantageously, this signal is emitted on the basis of the selective activation of the oscillator 35 and of the power amplifier 34 by respective activation signals generated by the microcontroller 15. Basically, the microcontroller 15, for each PPM pulse of the PPM signal to be generated, first activates only the oscillator 35 for a first period of time, and then also activates the amplifier 34 for a second period of time after the first period of time. This means that the oscillator 35 and the power amplifier 34 are activated so that the oscillator 35 is activated before activating the power amplifier 34, and is deactivated at the same time as, or after, the power amplifier 34 is deactivated.

The transmission device 1 is advantageously a short-range device powered by an energy source 20, for example a battery or an energy harvesting source.

The detection signals originate from detection means 25 which are connected or can be connected to the microcontroller 15 and which are adapted to detect one or more measurements of a certain physical quantity (for example, one or more of pressure, temperature, acceleration, vibration, voltage, etc.) and to generate detection signals that correspond to the values of such measurements. The detection means 25 can consist substantially of at least one transducer ("DM" in the figure) for each physical quantity to be measured. The transducer DM can be connected to a suitable input of the microcontroller 15 and can be a sensor selected from the group comprising, for example, a pressure sensor, a temperature sensor, a vibration sensor, an accelerometer, a magnetometer, a strain gauge, an inductive sensor, a voltage or current detector, etc.

The detection means 25, and also an optional RFID tag 30 of the transmission device 1, can optionally be powered by the microcontroller 15.

The transmitting device 1, 10 further comprises a covering element 5 (preferably of plastic material), such as for example a cover, a shell or a covering wall, which covers the printed circuit board 2 in an upper region and therefore also the at least one chip 3.

In the preferred embodiments, the covering element 5 is part of a boxlike body (preferably all made of plastic material) which includes inside it the chip 3, the PCB 2, the antenna 4A, 4B; 40A, 40B and any other electronic component (for example a battery or other power supply device 20 comprised in the device 1, 10). The antenna 4A, 4B; 40A, 40B comprises a first portion 4A; 40A printed on the printed circuit board 2, so as to be functionally connected to the chip 3.

The first portion 4A; 40A can be printed on the board with one of the conventional methods in the sector.

According to the invention, the antenna 4 A, 4B, 40 A, 40 A also comprises a second portion 4B, 40B which is printed on the covering element 5 so as to be positioned above the chip 3, as can be seen from the figures. The term “above” means on the opposite side with respect to the printed circuit board 2, so that when the second portion 4B; 40B of antenna is projected at right angles to the printed circuit board, this projection falls (at least partially and preferably completely) in the part of the board occupied by the chip 3.

This solution makes it possible to reduce the overall space occupation of the device 1, 10 while maintaining a highly effective signal transmission.

The two portions 4A, 4B; 40A, 40B of the antenna are both parts of the same antenna, i.e. they cooperate to emit the same signal, and therefore they are a continuation of each other, or in any case they are both functionally connected to the same chip 3.

Note that in the first embodiment (Figures 1-2) the two portions 4 A, 4B are formed from a single wire or trace, without discontinuities.

The second portion 4B, 40B can be printed on the covering element with one of the conventional printing methods on an insulating substrate.

In some, particularly advantageous embodiments, including those illustrated, the first portion 4A; 40 A and the second portion 4B; 40B have a fractal shape.

According to an optimal solution, present in the two embodiments illustrated, this fractal shape is a Koch curve fractal, i.e. a set of broken lines drawn starting from a segment from which the central third is removed and replaced with two other segments as long as the eliminated segment, and then reiterating this process one or more times. In the particular examples illustrated, this fractal shape is provided starting from a square along the perimeter of which a series of star-shaped profiles is drawn, each one having three vertices pointing outward, alternating with polygonal recesses formed from five segments.

Preferably, the lengths of the first portion 4A, 40A and of the second portion 4B, 40B are substantially equal.

It is useful at this point to specify that, in the present description and in the accompanying claims, the “length” of the antenna or of the portion means the length, or linear extension, of the wire or trace that forms such antenna or portion of antenna.

Preferably, the shapes of the first portion 4A, 40A and of the second portion 4B, 40B are substantially equal (whether fractal or not).

According to an optional and advantageous characteristic, the plan projection of the second portion 4B, 40B is completely contained in the chip 3, i.e. the orthogonal projection of the second portion 4B, 40B on the board 2 falls completely within the orthogonal projection of the chip 3 on that board 2, as shown in Figures 2 and 5.

The antenna 4A, 4B, 40A, 40B can be made as a quarter-wave antenna (as in the first embodiment of Figures 1-3) or as a half- wave antenna (as in the second embodiment of Figures 4 and 5).

In the first case, as in the first embodiment, the chip 3 is configured to emit a signal with a preset wavelength and the antenna 4A, 4B has an overall length such that it is a quarter-wavelength with respect to the signal emitted by the chip (i.e. with a length equal to a quarter of the wavelength), so as to be a monopole quarter- wavelength antenna 4 A, 4B.

Conveniently, in this case, where the antenna is a quarter-wave monopole antenna, the second portion 4B forms a single antenna pole and the first portion 4A serves as a ground. Note therefore that, in this case, only the second portion 4B is directly connected to the chip 3 (by way of a connecting end 14 from which the signal is emitted, as an electrical output, by the chip 3), while the two portions are connected by a connecting portion 42 which also contributes to the total length of the antenna.

For example, in the embodiment illustrated in Figures 1-3, with the chip configured to generate a signal at approximately 434 MHz, the wavelength is approximately 691 mm, the quarter- wave is approximately 173 mm, each one of the two antenna portions 4 A, 4B is approximately 86 mm long, the connecting portion 42 is approximately 1 mm long and therefore the overall length of the antenna is 173-174 mm, and each one of the two portions of fractal shape can be contained in a square measuring 6 mm on a side.

In the second case, as in the second embodiment illustrated, the length of the antenna 40A, 40B is such that it is a half-wavelength with respect to the signal emitted by the chip 3 (i.e. a length substantially equal to half of the wavelength) so as to be a dipole half-wavelength antenna.

Note therefore that, in this case, each one of the portions 40A, 40 B is directly connected to the chip 3 by way of a respective connector 41A, 41B (or connecting end). The first connector 41 A which connects the chip 3 to the first portion 40A is connected thereto by a connection branch 43A which contributes to the total length of the antenna.

In the half-wave embodiments, the length of the antenna is double with respect to those of the quarter- wave embodiments: for example, in the embodiment illustrated in Figures 4-5, with the chip 3 configured to generate a signal at approximately 434 MHz, the wavelength is approximately 691 mm, the half- wavelength is approximately 346 mm, each one of the two antenna portions 40 A, 40B is approximately 172-173 mm long, the connection branch 43A is approximately 1 mm long and therefore the overall length of the antenna is approximately 346 mm, and in this case again each one of the two portions of fractal shape can be contained in a square measuring 6 mm on a side. In this latter case the reduced encumbrance is obtained by virtue of the fact that both portions 40A, 40B of the antenna are formed by a double line, i.e. the trace (or wire) is printed so that in each portion 40A, 40B it describes a same shape (in this case fractal) twice, one internal and one external, so as to form an inner branch and an outer branch which are mutually parallel.

The operation of the transmitting device 1, 10 is entirely similar to the operation of conventional transmitting devices.

The present invention also relates to a method for providing a transmitting device 1, 10 of the type described above, such method, in its essential parts, comprising the steps of:

- printing a first portion 4A; 40A of the antenna 4A, 4B; 40A, 40B on the printed circuit board 2;

- printing a second portion 4B; 40B of the antenna 4A, 4B; 40A, 40A on the covering element 5 intended to cover the board 2 and the chip 3, so that such second portion 4B; 40B, after positioning the covering element 3 to cover the board 2, can be positioned above the chip 3.

Preferably the first 4 A; 40 A and the second 4B; 40B portions of antenna are printed so as to provide the transmitting device with one or more characteristics of the preferred embodiments described above in detail.

According to a particularly advantageous possible solution, the chip 3 and the first portion 4A, 40A of antenna are provided together with the printed circuit board 2 with the known technique of packaging integrated components in the packaging material itself (known as “embedded component packaging”) based on the use of additive 3D technology or additive manufacturing, or, alternatively, using one or more conventional techniques for integrating the components in the substrate (carrier), such as System In Package technology.

In practice it has been found that the transmitting device, according to the present invention, achieves the intended aim and objects in that it can be made with reduced overall dimensions while retaining sufficient efficacy in signal emission.

Another advantage of the transmitting device, according to the invention, consists in that is easy to implement and it is economically competitive.

Another advantage of the transmitting device, according to the invention, consists in that it is highly versatile and offers competitive performance with respect to the background art.

Furthermore, the present invention provides a valid alternative to the background art.

The transmitting device, and the method for providing it, thus conceived are susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

Moreover, all the details may be substituted by other, technically equivalent elements.

The disclosures in Italian Patent Application No. 102022000023589 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A transmitting device (1, 10), particularly for low-power wireless sensors and even more particularly for use in loT systems, which comprises:

- a printed circuit board (2) on which at least one chip (3) configured to at least generate an electromagnetic signal is installed, said chip (3) being connected to an antenna (4 A, 4B; 40A, 40B) for emitting said signal;

- a covering element (5) which covers said printed circuit board (2) in an upper region; wherein said antenna (4 A, 4B; 40A, 40B) comprises a first portion (4A; 40A) printed on said printed circuit board (2); characterized in that said antenna (4 A, 4B; 40A, 40B) comprises a second portion (4B; 40B) printed on said covering element (5) so as to be positioned above said chip (3).

2. The transmitting device (1) according to claim 1, wherein said first portion (40A) forms a first antenna pole and said second portion (40B) forms a second antenna pole.

3. The transmitting device (1) according to claim 1, wherein said second portion (4B) forms a single antenna pole and said first portion (4A) serves as a ground.

4. The transmitting device (1) according to one or more of the preceding claims, wherein the at least one chip (3) is configured to generate a signal having a predetermined wavelength and wherein said antenna (4A, 4B) has a length substantially equal to one quarter of said wavelength.

5. The transmitting device (1) according to claim 2, wherein the chip (3) is configured to emit a signal with a predetermined wavelength and wherein said antenna (40A, 40B) has a length substantially equal to one-half of said wavelength.

6. The transmitting device (1) according to one or more of the preceding claims, wherein said first portion (4A; 40A) and said second portion (4B; 40B) have a fractal shape.

7. The transmitting device (1) according to the preceding claim, wherein said fractal shape is a Koch curve fractal.

8. The transmitting device (1) according to one or more of the preceding claims, wherein said first portion (4A; 40A) and said second portion (4B; 40B) have substantially equal lengths.

9. The transmitting device (1) according to one or more of the preceding claims, wherein said first portion (4A; 40A) and said second portion (4B; 40B) have substantially equal shapes.

10. The transmitting device (1) according to one or more of the preceding claims, wherein the plan projection of the second portion (4B; 40B) is completely contained in the chip (3).

11. The transmitting device (1) according to one or more of the preceding claims, wherein the at least one chip (3) comprises a microcontroller (15) and a pulse generator (33) connected to said microcontroller (15), said microcontroller (15) being configured to receive at least one detection signal which is representative of at least one measurement value and to control said pulse generator (33) so that it generates at least one PPM signal comprising information that corresponds to said at least one measurement value; said antenna (4 A, 4B) being configured for the radio transmission of said PPM signal; said pulse generator (33) comprising an oscillator (35) and a power amplifier (34) with an input connected to said oscillator (35) in order to amplify RF pulses in output from said oscillator (35) and to emit said PPM signal; wherein said microcontroller (15) is adapted, for each PPM pulse of said PPM signal to be generated, to activate only said oscillator (35) for a first period of time and then also activate the amplifier (34) for a second period of time following said first period of time.

12. A method for providing an antenna of a transmitting device (1, 10), particularly for low-power wireless sensors and even more particularly for use in loT systems, comprising: - a printed circuit board (2) on which a chip (3) configured to generate an electromagnetic signal is installed, said chip (3) being connected to an antenna (4A, 4B; 40A, 40B) for emitting said signal;

- a covering element (5) which covers said printed circuit board (2) in an upper region; said method comprising the steps of: a. printing a first portion (4 A; 40 A) of the antenna (4 A, 4B; 40 A, 40B) on said printed circuit board (2); characterized in that it comprises the step of: b. printing a second portion (4B; 40B) of said antenna (4 A, 4B; 40 A, 40B) on said covering element (5) so that it is positioned above said chip (3)-

13. The method according to the preceding claim, wherein said first (4A; 40A) and second (4B; 40B) antenna portions are printed so as to provide a transmitting device according to one of claims 1 to 10.