JP2001284945A - Active microwave reflector for scanning antenna to be electronically operated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active microwave reflector, with which costs are practically reduced rather than the cost of a well-known antenna concerning efficiency characteristics, for 2D scanning antenna to be electronically operated. SOLUTION: The antenna is composed of a microwave source to be linearly polarized for irradiating the reflector. This reflector is provided with one group of element cells and each of cells is provided with a phase shifter microwave circuit located in front of a conductive plane. This phase shifter is provided with a lead wire positioned on a support. Each of lead wires is provided with at least two double state semiconductor elements of diodes, for example. A microwave non-interference means is provided between cells and composed of a waveguide formed between two adjacent cells. The walls of these waveguides are parallel with polarized waves and a space between these waveguides disturbs the propagation of waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention is directed to an electronically steered scanning microwave reflector that can be illuminated from a microwave source forming an antenna.

[0002]

BACKGROUND OF THE INVENTION Electronically steered scanning antennas are typically formed by a group of radiating elements that emit microwaves. The phase of the microwave can be electronically controlled independently for each element or group of elements. Beam 2
An antenna capable of manipulating space in two orthogonal directions (2D) requires a huge number of radiating elements. These costs, i.e. the cost of the phase shifter and the corresponding electronic components, are usually much higher than this type of antenna.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to make a 2D electronically steered scanning antenna with comparable efficiency characteristics at substantially lower cost than known antennas. Is to make it possible.

[0004]

For this purpose, the antenna according to the invention consists of a linearly polarized microwave source illuminating an active microwave reflector. An active reflector according to the invention comprises a group of element cells, each cell comprising a phase shifter microwave circuit arranged in front of a conductive plane. The phase shifter includes a conductor or conductive track located on a support. Each of the conductors or tracks includes at least two two-state semiconductor elements, for example, diodes, connected to conductors that can individually control the states of the diodes, which are turned on or off for each of the diodes. It is possible. Therefore,
Four states can be obtained, and the geometric and electrical properties of the cell are such that a given phase shift value corresponds to each of these states. Finally, microwave anti-interference means are provided between the cells. These means consist in particular of a waveguide formed between two adjacent cells. The walls of these waveguides are parallel to the polarization, and the space between the waveguides becomes such that it impedes the propagation of the wave.

[0005] Other objects, special features and results of the present invention are given in the following description, given by way of example and illustrated by the accompanying drawings.

[0006] In these different figures, the same reference signs relate to the same elements.

[0007]

FIG. 1 is a schematic diagram of the principle used by an antenna according to the present invention.

[0008] antenna is parallel to the predefined direction OY, is formed by a polarized microwave O ₁ source S linearly. The antenna comprises an active reflector RA arranged in a plane containing the direction OY, for example in the plane of XOY.
Is irradiated.

The reflector RA is schematically represented in FIG. 2 and can be seen in a plan view (in the plane XOY).

The reflector comprises a group of juxtaposed element cells C, separated by an area 20 used for microwave decoupling of the cells. Each cell is capable of receiving a wave with an electronically steered phase value and reflecting the wave according to the method described further below.

Thus, by controlling the phase shift communicated with the waves received by each cell, it is possible in a known manner to form a microwave beam O ₂ (FIG. 1) in a desired direction. .

FIG. 3 shows an embodiment of the active reflector RA (plane YOZ is perpendicular to plane XOY).
1 provides a schematic cross-sectional view of FIG.

The reflector RA includes a microwave circuit CH, which is, for example, a substantially planar circuit for receiving the incident wave O ₁ ,
A conductive plane C positioned substantially parallel to the circuit CH at a predetermined distance d from the circuit CH;
C.

The conductive plane CC has a function of reflecting microwaves. It may be formed by any known means, such as, for example, parallel conductors in close proximity to each other, or a lattice structure, or a continuous plane. The circuit CH and the plane CC are preferably made on two opposite sides of the printed circuit type of the dielectric support 32.

On the same printed circuit 32 as a multilayer circuit, the reflector RA further has electronic circuits (parts and wiring) required for controlling the phase value. FIG.
Represents a multilayer circuit, having a circuit CH on its front surface 30,
An electronic component 132 is provided on the back surface 31. The intermediate layer forms a plane CC and, for example, two planes P1 for wiring between the circuit CH and the component 132.

FIG. 4 shows an embodiment of the microwave circuit CH.

The circuit CH consists of elemental phase shifters D made on the surface 30 and separated by non-interfering regions. Each phase shifter D coupled to a corresponding part of the conductive plane CC forms one of the element cells of FIG.

The phase shifter D is substantially parallel to the direction OY,
It includes one or more conductors F (only one in FIG. 4). Each conductor F has at least two two-state semiconductor elements D1 and D2, for example, diodes. This means, for example, that the cathodes of the diodes are connected in opposite directions. The supply voltages of the diodes D1 and D2 are transmitted by a plurality of control conductors. The control conductors are referenced CD and are substantially parallel to each other and perpendicular to the conductor F.
There are at least three or four of the conductors shown in the figure so that the diodes can be controlled independently of each other.

The phase shifters D are surrounded by their peripherally located conductive regions. Its surroundings are OX used for non-interference as described further below.
And a reference number 75 in a direction parallel to OY.

The conductor CD is connected to the electronic circuit of the reflector by using metallized holes 40 (41) made at the height of the conductive region 75. These conductive regions 75 are, of course, electrically insulated from these conductors (eg, by gaps 43 in regions 75).

As can be seen, the surfaces of the various conductors made, for example, by forming metal deposits on the surface 30, are hatched, although they cannot be seen in cross-section.

In order to explain the operation of the cell, it is first necessary to consider an equivalent circuit of the phase shifter D as shown in FIG.

Polarized linearly and parallel to OY and conductor F
(Electric field vector) incident microwave is applied to terminals B1 and
Received at B2 and connected in series parallel to terminals B1 and B2
Capacitance C₀, C_I1, C_I2, C_I3Passing
And C_I4to go into. Capacitance C₀Is the end conductor CD
Of non-interference between unit and conductive region 74 per unit length
Represents pacitance. Capacitance C_I1Is Daioh
Do D₁Per unit length between conductors CD surrounding
Represents pacitance. Capacitance C_I3Is the center conductor
Represents the capacitance per unit length between CDs. Ki
Capacitance C _I2Is C to diode D2_I1
Is the same as

The diode D₁Is the capacitance C_I1
Terminal. This diode D₁Also its equivalent
It is represented by a circuit diagram. This circuit diagram shows the inductance
L₁And its inductance L₁Is that connection
Diode D for line (F)₁Is the inductance of
And capacitance C_i1(Diode junction capacity
And a resistor R connected in series with the_i1(Reverse
Anti) or resistance R_d1(Forward resistance of diode)
Connect columns. This is the reverse diode D₁Or order
Direction diode D ₁This act is a switch
21.

[0025] Similarly, the diode _{D 2} is connected to a terminal of the capacitance _{C I2.} This diode D ₂
It is represented by its equivalent circuit diagram. This circuit diagram is the same as the circuit diagram of a diode D _1, reference numeral 2 is assigned to its components.

The microwave output voltage is the capacitance C
₀ , which occurs between terminals B3 and B4, which are the terminals of C _I1 , C _I2 and C _I3 .

The operation of the phase shifter D will now be described below. This description, in the first stage, there is no diode D ₂ and the central conductor CD to consider the operation of such a circuit. In the equivalent circuit diagram of FIG. 5, this is the unit D ₂
And the capacitances _CI2 and _CI3 .

[0028] When the diode _{D 1} is forward biased,
The susceptance (Bd1) of the circuit of FIG. 5 is expressed by the following equation.

[0029]

(Equation 1)

Z is the impedance of the incident wave, ω
Is the corresponding pulsation at the center frequency of the operating band of the device.

The parameters of the circuit are, for example,

(Equation 2) Is chosen to be This means that by looking at its conductance, the circuit is adapted, in other words, penetrating into the incident microwave, which leads to neither parasitic reflection nor any phase shift (dφ _d1 = 0). Specifically, the following equation is selected.

LC _I1 ω ² = 1

Any of the possible values of the capacitance C _i1 are as follows:

(Equation 3) Lead to.

[0034] When the diode _{D 1} is reverse-biased, the susceptance of the circuit _{(B r2)} is written by the following formula.

[0035]

(Equation 4)

The value of the capacitance _{C I1} is fixed in advance, the value of the susceptance _{B r1,} the capacitance C
The value of _i, i.e. can be adjusted by operation of the selection diode D _1.

[0037] In the second stage, if the presence of the diode D ₂ and the central conductors CD is considered, by the same process theory, against susceptance diode D ₂ depends on whether it is forward biased or reverse biased hand,
Two different values are given.

Therefore, the phase shifter D has its susceptance B
It can be seen that there can be four different values for _D (references _BD1 , _BD2 , _BD3 and _BD4 ). It is dependent on the applied instructions (forward bias or reverse bias) in each of the diodes D ₁ and D _2. These values are a function of the parameters of the circuit of FIG. That is,
Values selected for the phase shifter's geometric parameters (dimensions, shape and spacing of different conductive surfaces) and electrical parameters (electrical properties of the diode).

The whole cell, namely the phase shifter D and the conductive plane C
The operation of C will now be described. For the plane CC referred to by the _BCC , which can be replaced by the plane of the phase shifter and written as: susceptance needs to be considered.

B _CC = −cotg (2πd / λ)

Λ is the wavelength corresponding to pulsation ω.

Susceptance _{B C} of the [0042] cell is given by the following equation.

B _C = B _D + B _CC

Susceptance B_CIs the four values B_DInto it
Four corresponding different values (reference B_C1, B_C2, B
_C3And B_C4), And the distance d is the value B_C1
~ B _C4Represents an additional parameter for determining

Further, it can be seen that the phase shift (dφ) leading to the microwave by the admittance (Y) has the following equation.

Dφ = 2 arctanY

Therefore, the following equation can be understood from the real part of the admittance of the cell.

[0048]

(Equation 5)

Depending on the command applied to each of the diodes D ₁ and D ₂ , one obtains four possible values of phase shift per cell (dφ 1 to dφ 4). Four values dφ1 to dφ
4 is not compulsory but is 0, 90 °, 180 °, 2
Different parameters are selected that are equally distributed, such as 70 °.

It should be noted that the above description has been given of the case where the parameters of the circuit are selected.
The choice is such that the zero susceptance value (or substantially zero susceptance value) will correspond to a forward-biased diode, but the parameter is determined symmetrically to substantially eliminate the susceptance value Br. The operation type can be selected. More generally, it is not necessary either susceptance values B _d or B _r becomes zero. These values are
The phase shifts dφ1 to dφ4 are determined so as to match the equally dispersed state.

Furthermore, the cell should have one or more conductors F together with the diode, the operation and method of determining the parameters replacing the equivalent circuit with one of the same type,
Accordingly, wiring between conductors suitable for the diode can be considered.

The active reflector according to the invention also has non-interfering means between the cells C.

The microwave received by the cell is linearly polarized, parallel to the direction OY. This wave is in the direction O
It is desired that X should not be propagated from one cell to another. To prevent such propagation, the present invention places a substantially strip-shaped conductive region 75. The conductive region 75 is made by metal deposition on the surface 30, for example between the cells, parallel to the direction OY. This strip 75 along the lower reflecting plane CC forms a waveguide-type space whose width is the distance d. According to the invention, it can be seen that the distance d is chosen to be shorter than λ / 2 and that waves whose bias is parallel to the band cannot propagate in such a space. In fact, the reflector according to the invention operates in a band of frequencies, d being chosen to be shorter than the minimum wavelength of the band. Originally, when determining different parameters to fix the phase shifts d _{φ1 to} d _φ4 , it is necessary to consider this constraint. Furthermore, the band 75 must have a width e along the direction OX which is obviously sufficient for the above-mentioned effects. In practice, the width e is preferably in the range λ / 15.

In addition, waves may be created parasitically in the cell, with its polarization directed along direction OZ (perpendicular to directions OX and OY). It is also desirable to prevent its propagation towards adjacent cells.

For cells adjacent in the direction OX, metallized holes 40 to 41 can be used to connect the conductor CD and the electronic control circuit, as shown in FIG. In fact, these holes are parallel to the polarization of the parasitic wave and therefore equal to the plane of conduction. If they are sufficiently close to each other (at a distance shorter than the operating wavelength of the reflector), and if they consist of more, they form a shield for the operating wavelength of the reflector. If this situation cannot be realized, it is of course possible to form additional metallized holes without any connection function. These metalized holes 40-4
It should be noted that one is preferably made in the strip 75 so as not to interfere with the operation of the cell.

Finally, for cells adjacent in the direction OY, use the same metallized holes as in the direction OX but aligned with the holes 40-41, or use the plane XOZ as shown in FIG. It is possible to locate a continuous conductive surface. Plates 61 are shown extending from plane CC in a direction parallel to plane XOZ (the intersection of these plates 61 and surface 30 forms region 74 in FIG. 4). These plates may have a critically insignificant height, for example shorter than λ / 10, equal to λ / 10, or several times λ / 10, to improve interference,
It advantageously extends beyond the surface 30.

FIG. 7 shows another embodiment of a microwave circuit CH capable of making a two-polarized antenna.

This figure shows a perspective view of one cell C.
Phase shifting circuit has been made on the surface 30 of the substrate 32 is formed by two conductors F ₁ and F _2. Each of them comprises two diodes, such as D ₁₁ , D ₂₁ , D ₁₂ , D _22.
With one semiconductor element. These diodes are connected, for example, to identical central conductors 72, which themselves are connected by metalized holes 72 to the electronic control circuit of the reflector. Here each of the conductors suitable for a diode operates only on these waves, the polarization of which has parts parallel to the waves according to the same process as the one described above, taking into account the geometric differences of the conductors. Is done.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an antenna according to the present invention.

FIG. 2 is a plan view of an active reflector according to the present invention.

FIG. 3 is a cross-sectional view of one embodiment of an active reflector.

FIG. 4 is a plan view of one embodiment of a microwave circuit used in an active reflector.

FIG. 5 is an equivalent circuit diagram of the micro reflector.

FIG. 6 is a perspective view of a practical embodiment of the element for non-interference from cells with each other.

FIG. 7 is a configuration diagram of another embodiment of a microwave circuit capable of manufacturing a dual polarization antenna.

Continued on the front page (72) Inventor Michel Dubois, France, 91440 Bourg-sur-Yuvet, Avenix Sirculaire, 44 (72) Inventor Georges Gyomo, France, 91080 Courcouronu, Villera de Arcard, 3rd F-term (reference) ) 5J020 AA03 BA16 BC02 BC05 5J021 AA01 AB01 BA02 DB03 FA02 FA05 GA02 HA01 JA09 5J046 AA19 AB00 PA07

Claims (8)

[Claims] An active microwave reflector capable of receiving electromagnetic waves linearly polarized in a first given direction, comprising: a group of element cells positioned on a surface in close proximity to one another. Wherein each said cell includes a microwave circuit of a phase shifter and a conductive plane, the conductive plane being at a predetermined distance from the microwave circuit shorter than the minimum half wavelength of the operating band. Positioned substantially parallel to the microwave circuit, wherein the phase shifter circuit includes a dielectric support, wherein the dielectric support includes at least one electrical support substantially parallel to the given direction. A conductor positioned on the support and having at least two two-state semiconductor elements, wherein the conductor is connected to a control conductor for a semiconductor element substantially perpendicular to the conductor; Conductors are independent of each other And at least three second conductive regions positioned substantially parallel to the control conductor toward a peripheral direction of the cell to control a state of the semiconductor element. The characteristic will correspond to a given value of a phase shift (dφ1, dφ2, dφ3, dφ4) of the electromagnetic wave reflected by the cell, for each state of the semiconductor element, Electronic circuitry for controlling the state of the semiconductor element, connected to microwave non-interfering means between the cells, these means being positioned between each cell, parallel to the given direction. A reflector comprising a second conductive region, wherein the second conductive region, together with the conductive plane, forms a waveguide space in which waves cannot propagate. 2. The multilayer printed circuit according to claim 1, wherein said dielectric support has a first surface having said microwave circuit, a first intermediate layer having a conductive plane, and a second surface having components of said control circuit. The reflector according to claim 1, wherein the reflector is of a circuit type. 3. The reflector according to claim 2, wherein the dielectric support includes at least one second intermediate layer having wiring for the control circuit. 4. Includes a metallized hole,
At least some of the at least some of the connections providing a connection between the control circuit and the control conductor in a second direction substantially perpendicular to the first direction and at a distance between each other that is substantially less than an electromagnetic wavelength. 3. The reflector according to claim 2, wherein metallized holes are made in the dielectric support. 5. The reflector according to claim 4, wherein the metallized holes are created in the second conductive region without making electronic contact with the second conductive region. 6. The first conductive region is extended by a conductive plane substantially perpendicular to the first direction, and extends at least between the conductive plane and the phase shifter circuit. The reflector according to claim 1. 7. The reflector according to claim 1, wherein the semiconductor element is a diode. 8. An electronically steered scanning microwave antenna comprising the reflector according to claim 1 and a microwave source illuminating the reflector.