JPH02104101A - Phase shifting structure - Google Patents

Abstract

PURPOSE: To obtain compact antenna structure with comparatively light weight by integrating a waveguide phase shifter circuit to each slot so as not to provide the effect on the operation of a waveguide having a size in the lengthwise direction and propagating electromagnetic energy. CONSTITUTION: The electromagnetic energy emitted by a plurality of parallel rectangular waveguides 11 arranged in row and column directions is emitted from an aperture end of an aperture 13 of an antenna. A waveguide antenna array 10 includes a plurality of lengthwise direction slot 15 extended along the center of each column of the waveguide 11, each slot receives a phase shifter strip 17 and each strip is controlled so as to change a phase of a radiant ray supplied by the columns of the waveguides. Then a phase shifter circuit 20 is integrated to each slot 15 of the waveguide 11 so as not to provide effects on the operation of the waveguide 11. Thus, the structure of the compact antenna with comparatively light weight is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (INDUSTRIAL APPLICATION) The present invention relates generally to electronically controlled phased array antennas, and more particularly to electronically controlled phased array antennas capable of controlling electromagnetic energy propagated by a waveguide. Concerning a phase shift structure that shifts the phase to .

/ (Conventional Application) A phased array antenna is, for example, a directional antenna comprising individual radiating elements that generates an electromagnetic radiation pattern with a direction controlled by the relative phase of the energy radiated by the individual radiating elements. be.

That is, the radiation of the phased array is controlled by appropriately varying the relative phase of the individual radioactive elements. Such variation is provided by suitably changing the phase of the radiation emitted by each element. Such control is called beam steering or scanning.

Phased array antennas inherently perform scanning (
i.e., a change in beam direction). An example of a phased array antenna is a group of parallel, apertured waveguides, each waveguide being a radiating element.

It is known in the art that phased array antennas include receiving antennas that phase shift received electromagnetic energy to provide electronic scanning.

Previous layer knowledge about phased array antennas can be found in Introduction to Radar Systems.
system), 5kolnik, McGraw-Hi
11 Company, 1980.1962, Cha
Tail written on pter 8.

Conventional phase shifters include structures that change impedance with diodes.

As an example, 2 of the 5kolnik textbook mentioned above.
There is a periodic roped line phase shifter described on page 89, which uses diodes as switching elements. An important feature of this roped line phase shifter is that it requires a quarter wavelength spacing between the suspension patches, which limits the position of the diodes, and that a number of additional diodes are used. Additionally, roped line phase shifters have a large package when used with waveguides. Another example of a loaded line phase shifter that uses diodes is the RADANT system, also known as the “RADANT” system.
T: New Method of Electr
onic Scanning” 5M1c rowav
eJournal, February 1981, p.
p. 45-53.

An important feature of the RADANT system is that it requires a powered antenna, such as a horn, and that the diode grid or screen is located outside the waveguide.

Diode phase shifter for waveguide is Diode
Phase 5hifterand Model
in Waveguide”, Lester etal, 1
987 1EEE MTT-8Digest, pa
ges 599-602. However, this phase shifter is a single diode circuit with a laterally sloped structure, which complicates it when used with waveguides.

Conventional phase shifters further include electromechanical phase shifters in which circuit elements are mechanically moved. The important characteristics of electromechanical phase shifters are slow switching speed, large weight, and complexity of the electromechanical drive circuit.

Other types of conventional phase shifters require a phase shifting device, eg, a microstrip, that is separate from the main energy propagation medium, eg, a coaxial cable. Important features of such separate phase shifter devices include transitions, mismatching, and power loss.

(Problems to be Solved by the Invention) As described above, conventional phased array antennas have drawbacks such as complexity and slow switching speed when used with waveguides.

Therefore, a first object of the present invention is to provide a phase shift structure that is compact and provides high-speed switching.

Furthermore, a second object of the present invention is to provide an electronically controlled phase shift structure that can be easily incorporated into a waveguide.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a waveguide having a longitudinal dimension and propagating electromagnetic energy, and a waveguide of the waveguide. phase shifting means disposed therein and capacitively coupled to change the phase of the electromagnetic energy propagated by the waveguide.

(Operation) In the present invention, the phase shifter circuit is incorporated into each slot of the waveguide so as not to affect the operation of the waveguide, thereby providing a relatively lightweight and compact antenna structure. .

(Example) Hereinafter, an example of the phase shift structure of the present invention will be described with reference to the drawings. Like reference numerals are used for like elements in the following detailed description and drawings.

FIG. 1 is a partially cutaway perspective schematic diagram showing a waveguide antenna array 10 having a plurality of parallel rectangular waveguides 11 arranged in rows and columns. The electromagnetic energy radiated by the waveguide 11 is radiated from the open end formed by the aperture 13 of the antenna.

Waveguide antenna array 10 includes a plurality of longitudinal slots 15 extending along the center of each row of waveguides 11.
including. Each slot has a phase shifter strip 17
each strip is controllable to change the phase of the radiation provided by the array of waveguides.

In FIGS. 2 and 3, each phase,
Trip 17 is one example! It includes a dielectric planar substrate 19 made of a shirt. The plurality of shifter circuits 20 are fixed to each side of the substrate 19 in the column direction, and the shifter circuits on one side of the substrate 17 are symmetrical with the shifter circuits on the other side, forming a mirror configuration. Furthermore, the configuration of shifter circuit 20 is symmetrical about the center perpendicular to substrate 19.

The ends of each shifter circuit 20 are connected to top and bottom drive pads 21 and 23 located on each side of the substrate 19. Head drive pads 21 are conductively connected together, and bottom drive pads 23 are also conductively connected together. A control voltage is applied across the top and bottom drive pads 21 and 23.

Each phase shifter path 20 includes series connected diode/patch circuits 30, each circuit associated with a given waveguide, as shown in FIG. Each diode/
Patch circuit 30 includes first and second conductive patches 25a and 25b, each connected via a short, high impedance conductor 29 to the anode and cathode of a microwave diode 27, such as a PIN diode. .

Each diode/patch circuit 30 is connected to another diode/patch circuit 30 via a high impedance conductor 31 so that the conduction direction of each microwave diode 27 is the same.
Suitably connected to the susceptance patch or drive pad of the patch circuit. That is, the anode patch 25a of a given diode/patch circuit 30 is connected to the cathode patch 25b of the adjacent diode/patch circuit 30. As can be seen, each susceptance patch 25a and 25b has a corresponding height and width, the height being vertical and the width being lateral or horizontal.

To reduce connections between waveguides 11, conductive patches 25a and 25 of adjacent diode/patch circuits 30
The high inductance conductor 31 connecting b has at its end an RF choke inductor (not shown) connected to the patch.

As shown in Figure 2, the diode/patch circuit 3 in the head
The anode side conductive patch 25a of 0 is connected to the head drive pad 21 via a high inductance conductor 33. The cathode susceptance patch 25b of the bottom diode/patch circuit 30 is connected to the bottom drive pad 23 via a high inductance conductor.

Although FIG. 2 shows that a microwave diode 27 is arranged between the associated patches 25a, 25b, this diode can also be fixed at the ends of the associated conductive patch.

The susceptance present in the waveguide by phase shifter strip 17 is determined by the forward and reverse bias conditions of microwave diode 27.

When microwave diode 27 is forward biased, the first and second conductive batches of each diode/patch circuit 30 are conductively connected and high susceptance exists.

Such high susceptance results in radiated energy having a different phase than the radiated energy when diode 27 is reverse biased. That is, each phase shifter strip 17 has two states, forward bias and reverse bias, and the phase differs depending on the two states. The differential phase shift amount for the phase shifter strip is
It is controlled by the dimensions of the conductive patch and the effective dimensions of the connected conductive patch. The differential phase shift is (1
) represents the phase shift between the energy emitted when the shifter is reverse biased and (2) the energy emitted when the shifter is forward biased.

Impedance matching is achieved by selectively aligning each diode/patch circuit to a given phase shifter strip. The longitudinal spacing between phase shifter strips for a given row of waveguides must be large enough to prevent interference between phase shifter strips.

Diode 27 of a given phase shifter strip 17
is forward biased by selectively applying sufficient voltage across the top and bottom drive pads 21 and 23, with the top drive pad 21 being positive with respect to the bottom drive pad.

The voltage in this case must be greater than the sum of the forward bias voltage drops of the diodes 27 of the phase shifter. That is, if five diode/patch circuits 30 are connected in series within each phase shifter 20, and each diode 27 has a forward voltage drop of 1.2 volts, then the two across the top and bottom drive terminals The forward bias voltage must be at least 6 volts.

To prevent the diodes from becoming forward biased by waveguide propagating energy, e.g., -5 to -100 volts for each diode, reverse biasing by applying a sufficient negative voltage to the head drive pad. Bias is supplied.

FIG. 3 is a cross-sectional view of one of the waveguides 11, the cross-section of which is H-shaped, with centrally disposed parallel ridges 33 disposed symmetrically on either side of the longitudinal slot. For symmetry, the head and bottom ridges 33 have mirror images.

As shown in FIG. 3, the conductive patch at the top of the diode/patch circuit 30 for a given waveguide 11 is adjacent to the head ridge 33, and the conductive patch at the bottom of the diode/patch circuit is adjacent to bottom ridge 33. The adjacency of the conductive patch to the ridge 33 provides capacitive coupling of the conductive patch to the waveguide.

By way of example, the phase shifter strips 17 consist of digitally switched phase shifters that are provided with individual phase shifts, with each phase shifter strip 17 for a given column of waveguides providing a predetermined differential phase shift.

The amount of phase shift controllably induced by each phase shifter strip 17 is determined by the desired phase shift increase. That is, for a phase shift increase of 11.5 degrees, 5 phase shifters are used, each with 1
Provides a continuously increasing phase shift starting at 1.5 degrees.

Each phase shifter provides twice the phase shift of the next lower phase shifter strip.

In this example, the phase shifter strips are sequentially 11.
25.22.5.45.90 and provides a 180 degree phase shift. Such a phase shifter strip provides a phase shift of N×11.25 (N being an integer from 0 to 31).

In such a configuration, each phase shifter strip is called a "bit" and the desired phase shift is provided by turning on the appropriate bit. That is, for example, a bit with a phase shift of 33.75 degrees and a bit of 11.25 degrees
Provided by turning on the 2.5 degree bi-soto.

If a larger phase shift is required, additional bi-soto is used. For example, a bit of 5.625 degrees,! -2,8
If 125 degree bits are used, a 7-bit method is used, and in this case, an increase of '2.1825 degrees is obtained.

The phase shifter strip 17 has two basic states: reverse bias and forward bias. As a result, several phase shifter strips are used to provide different phase shifts. Further, each phase shifter circuit 20 of the phase shifter strip 17 is controlled to be individually reverse biased or forward biased.

For example, as shown in FIG.
This is achieved by supplying Considering symmetry, it is better to conductively connect the drive pads 21a for the associated mirror image phase shifter circuit 20 to both sides of the substrate 19. All phase shifter circuits 20 of the phase shifter strip 17 are connected together to a bottom drive pad 23 connected to a common reference voltage, e.g. ground, and the individual head drive pads 21a are individually selectively forward biased. Connected to voltage and reverse bias voltage. For example, for a phase shifter strip with three phase shifter circuits 20 on each side of the board:
Eight different combinations of susceptance are provided.

If phase shifter strips 17 with multiple forward bias states are used, only one phase shifter strip 17 is required for a given column of waveguides.

In FIG. 3, the illustrated waveguide 11 is
3. Contains a rectangular waveguide with a head and a bottom, but with a centrally located, longitudinally extending channel used to increase capacitive coupling, and a conductive patch reasonably close to the channel. It is located in On the other hand, rectangular waveguides without ridges or channels are also used, in which case the conductive patches are closely arranged on the upper and lower waveguide walls. Note that the absence of ridges or channels provides less tolerance for adjustment.

Phase shifter strips are used with circular waveguides and with or without capacitive coupling to strengthen the ridges or channels.

Although phased array antennas have been discussed generally in terms of radiated electromagnetic energy, they may also be used to shift the phase of received electromagnetic energy. The waveguide propagates either received energy or radiated energy.

In this case, the specified number of diode patches and patch dimensions are determined by the desired phase shift, waveguide characteristics, desired VS
Depending on factors including WR (Voltage Standing Wave Ratio), known design procedures are applicable to design a particular phase shifter strip. For example, the characteristics of different individual diode/patch circuits are determined for the waveguide structure to be used, for example by measuring two-port scattering parameters. From this scattering parameter, relevant transmission parameters are determined and used to design multiple diode/patch circuits on top of the phase shifter strip.

Such a design is DPSYN15. This is accomplished with the aid of an optimization computer program, such as the optimization program called FORT, which will be shown at the end of this description using a cubic Grandsch function interpolation routine called LAGRAN and a sample input data set D.
PSYN15°DATA and an output data set DPO based on the sample input data set
UT15. DATA, and sample basic data set KTPARM, HO40F.

DATA, KTPARM, HO40R, DATA.

KTPARM, HO5F, DATA.

KTPARM, HO50R, DATA.

KTPARM, HO65F, DATA.

It is listed along with the list of KTPARM and HO65R0DATA.

Optimization program DPSYN15. FORT is IM
A special function FORTR called the IMSL library obtained from SLS Inc., Hyeuston, Texas.
The optimization routine ZXSSQ in the AN library is used. Error residual calculation subroutine (er
role-residual calculations
ubrout 1ne) is the optimization routine ZXSSQ
Therefore, the optimization program DPSYN15°FORT must be used with the subroutine S
Including UB.

In general, the optimization program DPSYN15°FORT
allows an initial optimization of the conductive patch dimensions and spacing for a phase shifter strip with a predetermined differential phase shift. Based on the measured T-parameters listed in the basic data set, the program calculates the voltage standing wave ratio (VSWR) response of all diodes in the on state and all diodes in the off state and the associated dimensions and spacing optimization. Calculate the phase shift response. The difference between the actual and desired total responses is calculated,
Optimizations are adjusted to reduce the difference. The above process is repeated until the difference is less than or equal to a predetermined amount, or until a certain maximum number of repetitions is reached.

Sample input data set DPSYN15,D
In ATA, line 20 shows the desired differential phase shift. Line 30 is the error residual subroutine S
Maximum number of calls to UB and optimization routine ZXS
Two parameters used by SQ are shown. Line 40 shows the parameters used by the optimization routine.

Line 50 shows a number greater than the number of patches and the number of desired frequencies. Line 60 shows the minimum spacing between patches and the maximum width of the patches.

Lines 70-130 show the initial approximation used by the optimizer.

In lines 140-340, the first column shows the identification of a predetermined frequency that is not defined but corresponds to a frequency associated with the T parameter shown in the basic data set. The second column shows the desired VSWR and the third column shows the desired negative phase. The fourth column shows the desired VSWR weights, and the fifth column shows the phase shift weights. VSWR and phase shift weights allow identification of critical frequencies. Column 6 shows the propagation constants for the dielectrically loaded waveguide, and column 17 shows the propagation constants for the unloaded waveguide. Such propagation constant is the frequency implicitly identified by the first column. Optimization program DPSYN15. FORT also requires a T parameter for each mirror image bear's diode/patch circuit 30, with each bear having a
It has a diode/patch circuit (2 patches and 1 diode) and a mirror image in the form of a second diode/patch circuit (2 patches and 1 diode) on the other side of the substrate. Such T-parameters are shown in the basic data set, the number of which depends on the number of patch heights involved.

For each patch height, two basic data sets are required, one with forward bias and the other with reverse bias. 2 for each height
One basic data set contains data for several widths (eg, six widths).

The first line below the basic dataset name (for example, K
TPARM, HO50F, and 20 lines of DATA) indicate the patch height, the number of patch widths, and the number of frequencies. The next row is the first patch width, followed by N groups of 3 rows < (
N is the number of frequencies).

The leftmost item frequency identifier in the first row of each group of three rows (a real number with a fraction of all zeros, e.g. 4.0000
0000). The frequency identifier represents the actual frequency associated with the T parameter. The eight numbers following each frequency identifier are the magnitude and phase terms of the four T parameters.

The T parameters for each of the other patch widths of the basic data set are similarly shown after the row containing the single entry specifying the patch width. That is, since there are 21 frequencies in this basic data set, KTPARM,
Line 670 of HO50, DA, TA shows the second patch width, followed by 21 groups of three lines.

The basic dataset has 1470 to 1560 rows for a certain height, 1570 to 1660 rows for a half height, and 1670 to 1 rows for a third height.
Read by the 760 line optimization program. For each height, first the forward biased data is read, then the reverse biased data is read.

The optimization program uses the basic data set to measure the T-parameters of patches of any size, provided the dimensions are within the n1 defined data range.

The approximated patch size and spacing T-parameters are calculated by performing two interpolations on the basic data set of measured T-parameters.

The first interpolation is an interpolation for the patch width for each height of each T parameter. The interpolation of this dimension is a cubic Lagranche interpolation and uses the LAGRAN subroutine described above.

The second interpolation is a cubic interpolation of each patch width to the patch height, subroutine GNT
Powered by ERP.

(For Hubic interpolation, four patch heights are required for each given patch width, one of which has zero height.

Output data set DPOUT15. DATA is 20
550 rows of a human data set are shown.

Line 620 represents the number of calls to the optimization subroutine SUB, and line 680 represents the number of calls to the optimization subroutine SUB, and line 680 represents the number of calls to the optimization subroutine SUB, and the error residual SSQ 2 for the response along with the final patch size and spacing approximation.
It shows the sum of the powers. Line 710 indicates whether the optimization routine's criteria were satisfied.

Lines 740-880 show the final patch size and spacing approximations obtained by the optimization program.

Lines 900-1150 show the response of the final patch approximation for forward bias conditions. The first column shows the frequency, the second column shows the voltage standing wave ratio, the third column shows the transmission phase of the phase shifter section, the fourth column shows the magnitude of the transmission coefficient, and the fifth column shows the voltage standing wave ratio. , represents the insertion loss in decibels.

Lines 1170-1410 show the response of the final patch approximation in the reverse bias or off state. Column is 9
They are arranged similarly to the forward bias responses in rows 00 to 150.

Lines 1430-1640 show the differential phase shift response of the final patch approximation. The first column shows the frequency and the second column shows the differential phase shift. The input for the second column is
For each frequency, it is calculated by subtracting the on-state transmission phase from the off-state transmission phase.

What has been described above is a specific description and illustration of the invention, and many other changes and changes may be made by those skilled in the art without departing from the scope and spirit of the invention.

[Effects of the Invention] As described above, the phase shift structure according to the present invention is relatively lightweight because the waveguide phase shifter circuit is incorporated into each slot so as not to affect the operation of the waveguide. provides a compact antenna structure. It also requires no media transitions and provides excellent impedance matching. Furthermore, the structure is uncomplicated and compatible with automated manufacturing processes.

[Brief explanation of the drawing]

1 is a partially cutaway perspective view of a waveguide phased antenna array incorporating the phase-shifting structure of the present invention; FIG. 2 is a diagram illustrating the needs-shifting structure of the present invention; FIG. The figure is a cross-sectional view of one of the waveguides of FIG.
FIG. 4 is a diagram showing another embodiment of the phase shift structure of the present invention. 10... Antenna array, 11... Waveguide, 15.
...Slot, 17...Phase shifter strip,
19... Board, 20... Shifter circuit, 21... Head drive pad, 23... Bottom drive pad, 25a...
- First conductive patch, 25b... second conductive patch,
27...Microwave diode, 30...Diode/patch circuit. Applicant's agent Patent attorney Takehiko Suzue

Claims (10)

[Claims] (1) A waveguide having a longitudinal size and propagating electromagnetic energy, and the electromagnetic energy disposed inside the waveguide and capacitively coupled and propagated by the waveguide. A phase shift structure characterized by comprising: phase shift means for changing the phase of energy. (2) The phase shift means controls first and second conductive regions disposed inside the waveguide and capacitively coupled, and the first and second conductive regions. 2. A phase shift structure according to claim 1, further comprising switch means for enabling and conductive coupling. (3) the first and second conductive regions include first and second conductive patches secured to a substrate, and the switch means is between the first and second conductive patches; A phase shift structure according to claim 2, characterized in that it comprises coupled diodes. (4) The phase shift structure according to claim (1), wherein the waveguide includes means for capacitively coupling the phase shift means to the waveguide. 5. A phase shift structure according to claim 4, wherein said means for capacitively coupling comprises a longitudinally extending capacitive coupling edge. (6) a waveguide having a size in a longitudinal direction and propagating electromagnetic energy; a planar substrate; first and second conductive regions disposed on the planar substrate; switch means for controllably and conductively coupling two conductive regions; and a switch means for disposing said first and second conductive regions within said waveguide. a slot extending longitudinally along a central portion to receive the planar substrate;
When the first and second conductive regions are controlled by the switch means, the phase of the electromagnetic energy propagated by the waveguide changes between the coupled and uncoupled states of the first and second conductive regions. means for capacitively coupling the first and second conductive regions to the waveguide so as to be controlled by the waveguide. 7. The phase of claim 6, wherein the first and second conductive regions comprise conductive patches on the substrate and the switching means comprises a diode. shift structure. (8) The means for capacitively coupling comprises a wall of the waveguide.
) Phase shift structure described. (9) A phase shift structure according to claim (6), wherein said means for capacitively coupling comprises a longitudinally extending ridge. (10) a waveguide having a length in a longitudinal direction and propagating electromagnetic energy; a planar substrate; first and second conductive patches disposed on the planar substrate; a switch means for controllably and conductively coupling two conductive patches; and a switch means for disposing said first and second conductive patches within said waveguide. a slot extending longitudinally along a central portion to receive the planar substrate; and when the first and second conductive patches are controlled by the switch means, the electromagnetic energy propagated by the waveguide. The phase of the first and second
longitudinally extending means for capacitively coupling the first and second conductive patches to the waveguide as controlled by the coupled and uncoupled states of the conductive patches. Phase shift structure characterized by.