CN1996664A - A directly radiated media lens and its application in the micro-wave near field detection - Google Patents

Abstract

This invention relates to one direct medium lens and its application in microwave detection, whose radio medium lens is composed of several dielectric parameters with equal difference change films for one to n between antenna and test objects. This invention method comprises the following steps: setting two different structure medium lens C and C'between antenna radiation surface A and test object with each lens composed of n pieces of medium slices C1-Cn and C'1-C'n with equal dielectric difference.

Description

A kind of direct-injection type di-lens and the application in microwave near-field detects thereof

Technical field

The present invention relates to a kind of microwave near-field detection technique, refer in particular to a kind of direct-injection type di-lens and in Microwave Measurement, use.

Technical background

In the application of near field imaging, and point-to-point, some high-order application technology aspect such as wireless telecommunications to multiple spot, system requires higher usually for the gain of antenna.Yet, the antenna that the single antenna unit forms, gain is difficult to be higher than 20dBi.In order to improve antenna gain, can main beam be focused on according to the light refraction principle: when light process optical lens, light will be assembled or disperse; This principle is applied to electromagnetic wave propagation, has obtained the notion of di-lens: when electromagnetic wave process di-lens, main beam will effectively focus on, to improve antenna gain.

The application of di-lens theory in antenna is very extensive, along with studying for a long period of time and developing this technology.The form of di-lens has multiple version, and the material that constitutes lens can be uniform medium, also can be the periodic structure that metal grid mesh or sheet metal etc. are formed; The shape of lens can be a spherical, also can be the flat thin template.And at present the most frequently used di-lens mostly is focusing di-lens, when its between the face battle array and the centre of sphere time, the electromagnetic wave that is sent by every bit on the face battle array can not change radiation angle behind these lens, with plane wave illumination near the centre of sphere.

Yet, focusing di-lens generally can only be used with surface antennas such as Cassegrains, if when transmitting antenna is selected novel microstrip antenna or dielectric waveguide antenna for use, electromagnetic wave enters air through the base (dielectric constant is the perfect medium of ε 1) of transmitting antenna, enters the reception antenna zone that dielectric constant is ε 2 by air again, twice via interfacial incident process in, to reflect, scattering ..., and causing bigger phase shift and decay, this is that we do not wish to see.

$\frac{{\mathrm{\λ}}_1}{{\mathrm{\λ}}_2}=\frac{{\mathrm{\ν}}_1}{{\mathrm{\ν}}_2}=\frac{\sin \mathrm{\α}}{\sin \mathrm{\β}}=\frac{\sqrt{{\mathrm{\μ}}_2{\mathrm{\ϵ}}_2}}{\sqrt{{\mathrm{\μ}}_1{\mathrm{\ϵ}}_1}}=\frac{k_2}{k_1}$

According to the electromagnetic wave propagation principle: when electromagnetic signal entered medium 2 by medium 1, promptly wavelength was directly proportional with velocity of wave, be inversely proportional to eigenvalue, and the ratio of the sine of incidence angle α and the sine of refraction angle β, equal the velocity of wave ν of incident wave in first medium ₁With the velocity of wave ν of refracted wave in second medium ₂The ratio.

Therefore, when the UWB signal when the DIELECTRIC CONSTANT 1 first less medium enters bigger second medium of DIELECTRIC CONSTANT 2, signal is assembled, and effective wavelength will reduce, propagation velocity will slow down; Otherwise, when the UWB signal when the DIELECTRIC CONSTANT 1 first bigger medium enters less second medium of DIELECTRIC CONSTANT 2, signal is dispersed, and effective wavelength will increase, propagation velocity will be accelerated.

Carry out in the input and beam forming process of electromagnetic field in microwave technical field, for sensitivity and the accuracy that improves detection, require the gain coefficient of transmitting antenna big as far as possible, electromagnetic energy is aggregated in transmission course as far as possible, electromagnetic wave is finally entering the process of reception antenna through a plurality of different transmission mediums from transmitting antenna simultaneously, the reflection that causes on the interface of different medium layer, refraction, scattering are as far as possible little.

If directly through free space target approach medium, can there be three problems in high-frequency electromagnetic field signal by transmitting antenna produces:

(1) since seriously not the matching of electromagnetic property between antenna, free space and destination media will on the interface of antenna-free space and free space-destination media, produce than strong reflection;

(2) microwave system is to come the localizing objects position by the propagation delay time of gathering between direct wave and the scattered wave.To detect target propagation velocity very near, signal very fast again if antenna a period of time is left, then the propagation time of signal very short, cause time delay too little and can't be found probably.

(3) signal by transmitting antenna to around disperse the target field of having only seldom a part of wave beam to be radiated need to detect.

So how to make in the microwave transmission accomplish: not only make the reflection on the destination media interface as far as possible little; And can increase time delay again and effectively focus on the problem that electromagnetic wave just becomes the microwave technology industry.

Summary of the invention

Purpose of the present invention is intended to: propose to be used for the direct-injection type di-lens technology of Microwave Measurement, wish not only to make the reflection on the destination media interface as far as possible little in being applied to Microwave Measurement and transmission; And can increase time delay again and effectively focus on electromagnetic wave.

This direct-injection type di-lens and in Microwave Measurement, using, its direct-injection type di-lens is by being located at antenna and detecting the media sheet 1 that several dielectric constants between the target are the equal difference conversion ... the stacked composition of n.

Its application process is: place di-lens C, the C ' of 2 inverted configuration between aerial radiation face A and detection destination media B, each di-lens is the media sheet C that equal difference changes by n piece dielectric constant ₁-C _nAnd C ' ₁-C ' _nForm.

This direct-injection type di-lens that proposes according to above technical scheme, it is replaced originally between antenna and the detection target free space after.Can not only reduce the reflection of electromagnetic wave on each dielectric interface, effective focus signal, and reduce the propagation velocity of UWB signal, thereby under the constant situation of distance, increase signal propagation time, make time delay become obvious.

Description of drawings

Accompanying drawing 1 is for using dielectric antenna schematic diagram of the present invention;

Accompanying drawing 2 is the electromagnetic field distribution map of the di-lens that is stacked to;

Accompanying drawing 3 is used schematic diagram for the near-field microwave target detection.

Embodiment

This direct-injection type di-lens as shown in the figure, with and in Microwave Measurement application technology, direct-injection type di-lens wherein is by being located at antenna and detecting the media sheet 1 that several dielectric constants between the target are the equal difference conversion ... the stacked composition of n.

Its application process is: place di-lens C, the C ' of 2 inverted configuration between aerial radiation face A and detection destination media B, each di-lens is the media sheet C that equal difference changes by n piece dielectric constant ₁-C _nAnd C ' ₁-C ' _nForm.

The technical scheme that provides from accompanying drawing 1: aerial radiation face (supposing that dielectric constant is 50) and detect the di-lens of placing 2 inverted configuration between the destination media (suppose that dielectric constant is 36), each di-lens is made up of the media sheet that 9 dielectric constants are the equal difference variation.The structure of di-lens 1 and principle be as shown in Figure 1: from top to bottom, the DIELECTRIC CONSTANT of thin slice is and increases progressively trend, gets 55,60,65,70,75,80,85,90,95 respectively; Di-lens 2 is opposite with 1, and the DIELECTRIC CONSTANT of the thin slice trend that tapers off gets 100,92,84,76,68,60,52,44,36 respectively.

Among the figure:

(1) medium slot antenna (2) dielectric material 1 (3) dielectric material 2

(4) dielectric material 3 (5) dielectric materials 4 (6) dielectric materials 5

(7) dielectric material 6 (8) dielectric materials 7 (9) dielectric materials 8

(10) destination media

From electromagnetic energy distribution shown in Figure 2 as can be seen:

On each interface because the dielectric constant of both sides medium differs very little, coupling better, so signal areflexia almost; Signal has obtained effective focusing.

In addition, since the DIELECTRIC CONSTANT of di-lens far above the DIELECTRIC CONSTANT of free space ₀, the propagation time of direct wave and scattered wave all will increase, and the delay character between them is with apparition.

Claims (2)

1 one kinds of direct-injection type di-lenses and in Microwave Measurement, using, its direct-injection type di-lens is by being located at antenna and detecting the media sheet 1 that several dielectric constants between the target are the equal difference conversion ... the stacked composition of n.

2, a kind of direct-injection type di-lens as claimed in claim 1, it uses its application process in Microwave Measurement: place di-lens C, the C ' of 2 inverted configuration between aerial radiation face A and detection destination media B, each di-lens is the media sheet C that equal difference changes by n piece dielectric constant ₁-C _nAnd C ' ₁-C ' n forms.

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