WO2000045465A1

WO2000045465A1 - Switched circular polarization antenna and switched circular polarization phased-array antenna

Info

Publication number: WO2000045465A1
Application number: PCT/JP1999/006483
Authority: WO
Inventors: Tsunehisa Marumoto
Original assignee: Nec Corporation
Priority date: 1999-01-29
Filing date: 1999-11-19
Publication date: 2000-08-03
Also published as: JP2000223942A; AU1184500A

Abstract

A switched circular polarization antenna comprises a radiation element (11) that radiates two linearly polarized waves orthogonal to each other; first and second 180° phase shifters (12a, 12b); and a 90° hybrid circuit with one end (13) terminated. Such a switched circular polarization antenna or a switched circular polarization phased-array antenna has improved cross-polarization discrimination.

Description

Description Circularly polarized wave switching type antenna and circularly polarized wave switching type phased array antenna

The present invention relates to a circularly polarized antenna and a circularly polarized phased array antenna that radiate circularly polarized waves, and more particularly, to a circularly polarized wave switching type antenna and a circularly polarized wave switching type phased antenna having a function of switching the rotation direction of circularly polarized waves. Related to array antenna. Background art

FIG. 8 is a block diagram showing the configuration of a conventional circularly polarized wave switching type antenna. As shown in FIG. 8, the conventional circularly-polarized switching antenna includes a radiating element 111, a 90 ° hybrid circuit 113, and a switching circuit 119.

The radiating element 111 is a two-point feeding type patch antenna having two feeding points llla and 111b. The feed points 1 1 1 a and 1 1 1 b are arranged in a direction at about 90 ° from the center of the radiating element 1 1 1.

The 90 ° hybrid circuit 113 has four terminals 113a, 113b, 113c, and 113d, and has the following functions. That is, when power is input from the terminal 113a, the input power is divided into two equal parts so that the terminal 113c leads the terminal 113d by 90 ° in phase. Amplitude power is output from terminals 113c and 113d, respectively. On the other hand, when power is input from terminal 113b, the input power is bisected so that terminal 113c has a 90 ° phase delay with respect to terminal 113d. The same amplitude power is output from each of the terminals 113c and 113d. In this specification, there are expressions indicating phase angles such as 0 °, 90 °, and 180 °, but these values are also nominal values and deviations, and the actual exact angle is different from the nominal value. Note in advance that it is slightly off.

Conversely, when power is input from each of terminals 113c and 113d, the input power at terminal 113c is 90 ° ahead of the input power at terminal 113d. Then, these input powers are combined and output from the terminal 113 b. On the other hand, if the input power at the terminal 1 13 c is delayed 90 ° in phase with respect to the input power at the terminal 113 d, Output from

Terminals 113c and 113d of the 90 ° hybrid circuit 113 having such a function are connected to feed points 111a and 111b of the radiating element 111, respectively. The switching circuit 1 19 switches the rotation direction of the circularly polarized wave radiated from the radiating element 1 11. The switching circuit 119 has three terminals 119a, 119b, and 119c. A power supply for exciting the radiating element 111 is supplied to the terminal 119a. This power is output from one of the terminals 119b and 119c. Terminals 119b and 119c are connected to terminals 113a and 113b of the 90 ° hybrid circuit 113, respectively.

Next, the operation of the conventional circularly polarized wave switching type antenna shown in FIG. 8 will be described.

First, the terminal 119b of the switching circuit 119 is turned on, and the terminal 119c is turned off. At this time, the supplied power is output from the terminal 119b and input to the terminal 113a of the 90 ° hybrid circuit 113. This feed power is split into two by the 90 ° hybrid circuit 113 and supplied to the feed points 1 1 a and 1 1 b of the radiating element 1 1 1. At this time, the phase of the power supplied to the feeding point 111b is advanced by 90 ° with respect to the power supplied to the feeding point 111b.

Since the feed power having such a phase relationship is input almost orthogonally to the radiating element 111, a right-handed circularly polarized wave is radiated from the radiating element 111 (however, the radiation direction is set to the back side of the paper). From the front).

Similarly, when the terminal 119b of the switching circuit 119 is turned off and the terminal 119c is turned on, a left-handed circularly polarized wave is emitted from the radiating element 111.

Thus, by controlling the output of the switching circuit 1 19, the rotation direction of the circularly polarized wave radiated from the radiating element 1 1 1 can be switched.

Most of the power supplied to the radiating element 111 is radiated as right-handed or left-handed circularly polarized light as the main polarization. However, part of the feed power is radiated as cross-polarization (circular polarization opposite to the main polarization) for the following reasons.

First, power is supplied to the radiating element 1 1 1 from the feeding points 1 1 1a and 1 1 1b. Due to the mismatch between the radiating element 111 and the transmission line connected to each feed point 111a, 111b, a part of the feed power is reflected from the radiating element 111 to the transmission line.

For example, when the terminal 1 19b side of the switching circuit 1 19 is turned on and the terminal 1 19 c side is turned off, as described above, the 90 ° hybrid circuit 1 13 The output is a power supply that is 90 ° ahead of the terminal 113d. Therefore, the phase of the reflected power from the radiating element 111 is also 90 ° ahead of the terminal 113c side of the 90 ° hybrid circuit 113 relative to the terminal 113d side. Therefore, the reflected power synthesized by the 90 ° hybrid circuit 113 is output from the terminal 113 b of the 90 ° hybrid circuit 113 to the terminal 119c of the switching circuit 119. .

However, now, the terminal 119c side of the switching circuit 119 is in an off state, that is, a cutoff state. Therefore, the reflected power returned to the terminal 119c is reflected by the reproduction switching circuit 119 and input to the terminal 113b of the 90 ° hybrid circuit 113.

When the reflected power is input from the terminal 113b of the 90 ° hybrid circuit 113, the input power is adjusted so that the terminal 113c has a 90 ° phase delay with respect to the terminal 113d. 2 distributed. For this reason, the left-handed circularly polarized wave is re-emitted from the radiating element 11 1 based on the reflected power output from the terminals 113 c and 113 d of the 90 ° hybrid circuit 113. The left-hand circular polarization based on the reflected power is a cross-polarization of the right-hand circular polarization based on the feed power.

As described above, the conventional circularly-polarized switching antenna shown in FIG. 8 simultaneously radiates not only the main polarization based on the feed power but also the cross polarization based on the reflected power. As a result, there is a problem that the cross polarization discrimination degree is reduced.

The present invention has been made to solve such a problem, and an object of the present invention is to improve the cross polarization discrimination of a circularly polarized wave switching type antenna.

Disclosure of the invention

In order to solve such a problem, a circularly polarized wave switching antenna according to the present invention includes a radiating element having two power supply points and radiating two linearly polarized waves orthogonal to each other; The first and second phase shifters with 180 ° phase shift connected to the A 90 ° hybrid circuit with two 90 ° phase differences, connected to the first and second phase shifters, and the other end terminated, and the phase shift of the first and second phase shifters set to 0 ° Or a control means for switching to 180 ° to emit right-handed or left-handed circularly polarized waves from the radiating element.

Alternatively, the circularly polarized wave switching antenna of the present invention has a radiation element having two feed points and emitting two linearly polarized waves orthogonal to each other, and four terminals and a first terminal. A 90 ° hybrid circuit that is supplied with power to excite the radiating element, a non-reflective termination coupled to the second terminal of the 90 ° hybrid circuit, and one end coupled to one feed point of the radiating element. A first phase shifter having the other end coupled to the third terminal of the 90 ° hybrid circuit and having a phase shift of 180 °, and one end coupled to the other feed point of the radiating element and the other. A second phase shifter whose end is coupled to the fourth terminal of the 90 ° hybrid circuit and the phase shift is 180 °, and the phase shift of the first and second phase shifters is 0 ° or 180 ° Control means for controlling the radiating element to emit right-handed or left-handed circularly polarized waves by switching to It may be composed of

In either case, the control means switches both the phase shift amounts of the first and second phase shifters to 0 ° or 180 ° as the polarization radiated from the radiating element, and changes the circular polarization in the first rotational direction. A wave is generated, and the phase shift amounts of the first and second phase shifters are switched to 0 °, 180 ° or 180 ° and 0 °, respectively, to generate a circularly polarized wave having a reverse rotation to the first rotation direction. .

The power supply output from the third terminal of the 90 ° hybrid circuit is 90 ° ahead of the power supply output from the fourth terminal. Therefore, if both the first and second phase shifters are in the 0 ° state or the 180 ° state, one feed point of the radiating element will be fed 90 ° ahead of the other feed point. Power is provided. On the other hand, if one of the first and second phase shifters is in the 0 ° state and the other is in the 180 ° state, one feed point of the radiating element is 90 ° away from the other feed point. ° Supply power with a delayed phase is provided. Therefore, by controlling the operation of the two phase shifters, the rotation direction of the circularly polarized wave can be switched.

On the other hand, the reflected power reflected at each feed point of the radiating element is combined by a 90 ° hybrid circuit and output from the second terminal. The reflected power output from the second terminal is absorbed by the non-reflective termination. Therefore, the 90 ° hybrid circuit side Since the returned power can be reduced, radiation of cross-polarization based on the reflected power can be suppressed. Therefore, according to the present invention, the cross polarization discrimination of the circularly polarized wave switching type antenna can be improved. These circularly-polarized switching antennas are cascaded to a 90 ° hybrid circuit and controlled by control means so that the amount of phase shift becomes 180 ° / 2 ^m (n is a natural number, m may be a different natural number from 1 to η) third phase shifters. Since the above-mentioned circularly polarized wave switching type antenna has the function of 180 ° phase shifter, the radiation phase is (seozs ¹ ). Can be controlled in steps.

One configuration example of the first and second phase shifters is a switched line type phase shifter. Thereby, the electrical characteristics of the first and second phase shifters can be improved.

One configuration example of the third phase shifter is a loaded line type phase shifter. Thereby, the electrical characteristics of the third phase shifter can be improved.

On the other hand, the circularly-polarized switched phased array antenna of the present invention has a radiating element having two feed points and radiating two linearly polarized waves orthogonal to each other, and a transfer element connected to each feed point of the radiating element. The first and second phase shifters with 180 ° phase amount and the input signal were split into two with a phase difference of 90 ° and connected to the first and second phase shifters, and the other end was terminated. A 90 ° hybrid circuit, and control means for switching the phase shift amounts of the first and second phase shifters to 0 ° or 180 ° so that the radiating element emits right-handed or left-handed circularly polarized waves. And a plurality of radiating elements, first and second phase shifters, a 90 ° hybrid circuit, and a plurality of control means are arranged in an array.

Alternatively, a circularly-polarized switched phased array antenna of the present invention includes a radiating element having two feed points and emitting two linearly polarized waves orthogonal to each other, a four-terminal terminal, and a first terminal. A 90 ° hybrid circuit in which power is supplied to the terminals to excite the radiating element, a non-reflective termination coupled to the second terminal of the 90 ° hybrid circuit, and one end coupled to one feed point of the radiating element A first phase shifter having the other end coupled to the third terminal of the 90 ° hybrid circuit and having a phase shift of 180 °; and one end coupled to the other feed point of the radiating element. The other end is coupled to the fourth terminal of the 90 ° hybrid circuit and the phase shift amount is 180 °, and the phase shift amount of the first and second phase shifters is 0 °. Or switch to 180 ° to radiate right-handed or left-handed circularly polarized light from the radiating element. Control unit for controlling A plurality may be provided and each unit may be arranged in an array.

In either case, the control means switches both the phase shift amounts of the first and second phase shifters to 0 ° or 180 ° as the polarization radiated from the radiating element and changes the phase shift amount in the first rotational direction. Generate a circularly polarized wave and switch the phase shift amounts of the first and second phase shifters to 0 °, 180 °, 180 °, and 0 °, respectively, to switch the first rotation direction and the reverse rotation. Generate circular polarization. These circular polarized-wave換形phased array antenna, 9 0 ° n the phase shift amount in the coupled and control means in cascade hybrid circuit is controlled to be ^{1 8 0 ° Z 2 m (} n is a natural number, m May be different natural numbers from 1 to n) third phase shifters.

In this way, by configuring the phased array antenna with the above-described circularly polarized wave switching type antenna as one unit, a circularly polarized wave switching type phased array antenna having a high degree of cross polarization discrimination can be realized.

In the above-described circularly polarized wave switching type phased array antenna, each unit may be two-dimensionally arranged. Thus, two-dimensional electronic scanning in the beam direction can be realized with a high degree of cross polarization identification.

The above-described circular polarization switching type has a multilayer structure including a layer on which a radiating element included in each unit is formed and a layer on which first and second phase shifters included in each unit are formed. May be provided.

Further, a distribution unit for distributing and supplying power to the 90 ° hybrid circuit included in each unit is further provided, and a layer in which the first and second phase shifters included in each unit are formed; It may have a multilayer structure including a layer on which the means are formed. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the configuration of a first embodiment of a circularly polarized switching antenna according to the present invention. It is a block diagram.

FIG. 2 is an explanatory diagram of the reverse-circularly-polarized radiation power of the circularly-polarized switching antenna shown in FIG.

FIG. 3 is an explanatory diagram of the reverse-circularly polarized radiation power of the circularly polarized switching antenna shown in FIG.

FIG. 4 is a block diagram showing a configuration of a second embodiment of a circular polarization switching antenna according to the present invention.

FIG. 5 is a block diagram showing the entire configuration of a circularly polarized wave switching type phased array antenna according to the present invention.

FIG. 6 is an exploded view showing the structure of the antenna unit.

FIG. 7 is a plan view showing an arrangement of one antenna unit formed on the antenna unit layer.

FIG. 8 is a block diagram showing a configuration of a conventional circularly polarized wave switching type antenna. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the case where the antenna transmits a signal will be described. However, it should be noted that the principle of operation is essentially the same even when the antenna receives a signal due to the reversible reasoning.

(First Embodiment)

FIG. 1 is a block diagram showing a configuration of a circularly polarized wave switching type antenna according to a first embodiment of the present invention.

The radiating element 11 is a two-point feed type patch antenna having two feed points 11a and 11b. The feed points 11a and 11b are arranged in a direction at about 90 ° from the center of the radiating element 11 so that two linearly polarized waves orthogonal to each other are radiated from the radiating element 11. .

The radiating element 11 has a circular shape, and the feeding points 11 a and 11 b are arranged on the outer periphery of the radiating element 11. However, the feeding points 11 a and 11 b may be arranged on the lower surface of the radiating element 11. The shape of the radiating element 11 is not limited to a circle, but may be a 90 ° rotationally symmetrical shape such as a square.

The 90 ° hybrid circuit 13 has four terminals 13a, 13b, 13c, and 13d, and has the following functions. That is, when power is input from the first terminal 13a, the input power is divided by two so that the third terminal 13c side is advanced by 90 ° with respect to the fourth terminal 13d side. Then, power of the same amplitude is output from each of terminals 13c and 13d.

Conversely, when power is input from each of the terminals 13c and 13d, if the input power at the terminal 13c is 90 ° ahead of the input power at the terminal 13d, The 90 ° hybrid circuit 13 combines these input powers and outputs the power from the fourth terminal 13 b. On the other hand, if the input power at terminal 13c is delayed 90 ° in phase from the input power at terminal 13d, the 90 ° hybrid circuit 13 combines these input powers. Output from terminal 13a.

The 90 ° hybrid circuit 13 having such a function includes, for example, a branch line type hybrid circuit and a 3 dB coupling line type directional coupler. Also, by adding a transmission line having an appropriate line length to the input / output terminal of the rat race ring circuit, a 90 ° hybrid circuit 13 having the same function can be configured.

Power supply power for exciting the radiating element 11 is supplied to the terminal 13 a of the 90 ° hybrid circuit 13.

A non-reflective termination 14 is coupled to a terminal 13 b of the 90 ° hybrid circuit 13. The non-reflection terminal 14 is formed by depositing a film resistor matching the same characteristic impedance as the terminal 13 b of the 90 ° hybrid circuit 13. This film resistance is formed by, for example, Ta, NiCr, and Ti. A non-reflection terminator externally attached by soldering, connector connection, or the like may be used.

Between the feed point 11a of the radiating element 11 and the terminal 13c of the 90 ° hybrid circuit 13 is a phase shift circuit (first phase shifter) with a phase shift of 180 ° 1 2 a is connected. A phase shift circuit (second phase shifter) with a phase shift of 180 ° is provided between the feed point 11 b of the radiating element 11 and the terminal 13 d of the 90 ° hybrid circuit 13. 12 is Are combined.

The phase shift circuit 12a is supplied with a first control signal s21 from a control circuit described later (see FIG. 5). Similarly, the second control signal s22 is supplied to the phase shift circuit 12b. The states of the phase shift circuits 12a and 12b are controlled by control signals s21 and s22, respectively.

That is, the control signal s 2 1, s 22 2 applied to the phase shift circuits 12 a and 12 b S is “off” (for example, logic level “shi”) ”or“ on ”(for example, logic level“ H ”). The phase when the supplied power passes through the phase shift circuits 12a and 12b changes by 180 ° depending on whether the power supply power is “)” or “)”. Here, the state of the phase shift circuits 12a and 12b when the control signals s21 and s22 are "off" is referred to as the 0 ° state, and the control signals s21 and s

22 The phase shifter 12a and 12b when the force S is ON is called the 180 ° state5.

Next, the operation of the circularly polarized wave switching type antenna shown in FIG. 1 will be described.

9 0 ° The power supplied from terminal 13 a of hybrid circuit 13 is supplied to terminal 1

3 c and 13 d are divided into two with the same amplitude. However, the feed power output from terminal 13c is 90 ° ahead of the feed power output from terminal 13d.

The feed power divided into two by the 90 ° hybrid circuit 13 is input to the radiating element 11 via the phase shift circuits 12a and 12b, respectively. At this time, the polarized waves radiated from the radiating element 11 are classified as follows according to the combination of the states of the phase shift circuits 12a and 12b.

(1) First, the case where both the phase shift circuits 12a and 12b are in the 0 ° state. At this time, the power supplied to the power supply point 11a is advanced 90 ° in phase from the power supplied to the power supply point 11b.

On the radiating element 11, a current Ia flows from the feeding point 11a toward the center. Similarly, current Ib flows from feed point 11b toward the center. The directions in which the currents Ia and I flow are almost orthogonal. The phase of the current Ia is ahead of the current Ib by 90 °.

For this reason, the right-handed circularly polarized wave is radiated from the radiating element 11 (however, the radiation direction is from the back side of the paper to the front side; the same applies hereinafter). The radiation phase at this time is based on the right-handed circular polarization. Determine 0 ° as the quasi-phase.

② Next, the case where both the phase shift circuits 12a and 12b are in the 180 ° state. At this point, the phase of the feed power input to feed point 11a is also 90 ° ahead of the feed power input to feed point 11b. Therefore, also in this case, the radiating element 11 emits right-handed circularly polarized light. However, the radiation phase is shifted by 180 ° with respect to the reference phase of ①.

③ Next, the case where the phase shift circuit 12a is in the 180 ° state and the phase shift circuit 12b is in the 0 ° state. At this time, the power supplied to power supply point 11a is delayed by 90 ° in phase from the power supplied to power supply point 11b. For this reason, radiating element 11 radiates left-hand circularly polarized light. The radiation phase at this time is determined to be 0 ° as the reference phase of left-hand circular polarization.

④ Finally, this is the case when the phase shift circuit 12a is at 0 ° and the phase shift circuit 12b is at 180 °. In other words, the power supplied to the power supply point 11a is delayed by 90 ° from the power supplied to the power supply point 11b. Therefore, radiating element 11 emits left-hand circularly polarized light. However, the radiation phase is shifted by 180 ° with respect to the reference phase in ③ above.

Table 1 shows the relationship between the states of the phase shift circuits 12a and 12b shown here and the state of the circularly polarized wave radiated by the radiating element 11.

In this way, by controlling the operation of the two 180 ° phase shift circuits 12a and 12b, the radiation of the radiating element 11 can be changed to 0 ° right-handed circularly polarized by the combination of the phase shift amounts. , 180 ° right-handed circular polarization, 0 ° left-handed circular polarization, and 180 ° left-handed circular polarization it can. In this manner, the circular polarization switching function and the function of the 180 ° phase shift circuit can be realized together by the phase shift circuits 12a and 12b and the 90 ° hybrid circuit 13.

In the configuration shown in FIG. 1, when both the 180 ° phase shift circuits 12 a and 12 b are in the 0 ° state or the 180 ° state, the right-handed circularly polarized wave (the circularly polarized wave in the first rotational direction) When only one of them is at 0 ° and the other is at 180 °, it is left-handed circularly polarized (circularly polarized in the opposite direction to the first rotation direction). By changing the position, the relationship between the states of the 180 ° phase shifters 12a and 12b and the polarization can be changed. That is, if the reflectionless termination 14 is connected to the terminal 13a of the 90 ° hybrid circuit 13 and power is input from the terminal 13b, the 180 ° phase shift circuits 12a and 12b are both in the 0 ° state. Or, when it is in the 180 ° state, it becomes left-handed circularly polarized light (circularly polarized light in the first rotation direction). When only one of them is in the 0 ° state and the other is in the 180 ° state, it is right-handed circularly polarized ( (Circularly polarized wave with opposite rotation to the rotation direction of 1).

Most of the power supplied to the radiating element 11 is radiated as right-handed or left-handed circularly polarized light. However, due to the mismatch between the radiating element 11 and the transmission lines connected to the feed points 11a and 11b, part of the feed power is reflected from the radiating element 11 to the transmission line. Here, the power reflected at the feed point 11a is called first reflected power, and the power reflected at the feed point 11b is called second reflected power.

Regarding the behavior of the first and second reflected powers in the circularly polarized wave switching type antenna shown in Fig. 1, when the phase shift circuits 12a and 12b are both in the 0 ° state or in the 180 ° state Will be described as an example.

As described above, the power supplied from the terminal 13 c of the 90 ° hybrid circuit 13 has a phase that is 90 ° ahead of the power supplied from the terminal 13 d. Therefore, the phase of the first reflected power is ahead of the phase of the second reflected power by 90 °. Therefore, the reflected power obtained by combining the first and second reflected powers is output from the terminal 13 b of the 90 ° hybrid circuit 13.

Most of the reflected power output from the terminal 13 b is absorbed by the non-reflection terminal 14. Therefore, the power returned to terminal 13b again is extremely small. Therefore, re-radiation of the first and second reflected powers as cross-polarized components can be suppressed. For this reason, the circularly-polarized switching antenna shown in FIG. Higher cross polarization discrimination can be obtained than the conventional circularly polarized switching antenna. The circularly polarized wave switching type antenna having such characteristics can be used for, for example, microwave communication, satellite communication, and a radar device using circularly polarized waves which are used while switching between orthogonal circularly polarized waves.

In the block diagram of Fig. 1, the radiating element 11 and the phase shift circuits 12a and 12b, the 90 ° hybrid circuit 13 and the non-reflective termination 14 are all drawn on a plane. It is not necessary to form them on the same plane when forming them, and the present invention is effective even if these are formed in different layers and laminated, and the layers are connected by coupling slots or through holes, power supply pins, etc. . For example, the layer on which the radiating element 11 is formed and the layer on which the phase shift circuits 12a and 12b, the 90 ° hybrid circuit 13 and the non-reflection termination 14 are formed are laminated, and the aforementioned coupling means, namely, The present invention is effective even if the layers are connected by coupling slots or through holes, power supply pins, or the like.

Further, the radiating element 11 is not limited to a patch antenna, but may be a dipole antenna or a slot antenna.

Next, the effects of the circularly-polarized switching antenna shown in Fig. 1 will be described using specific numerical values.

It is assumed that the cross-polarization discrimination of a single radiating element is 30 dB and its reflection coefficient is 20 dB (VSWR 1.22), and that the reflection coefficient of the non-reflection end 14 in Fig. 1 is 20 dB. (VSWR 1.22).

For simplicity, the transmission line, phase shift circuit, 90 ° hybrid circuit, radiating element, and other devices are all lossless, and the 90 ° hybrid circuit has ideal reflection characteristics, pass-phase characteristics, The explanation will proceed on the assumption that it has the characterization characteristics.

First, in order to compare with the circularly-polarized switching antenna shown in FIG. 1, the reverse circularly polarized radiation power of the conventional circularly-polarized switched antenna shown in FIG. 8 will be described with reference to FIG. .

Fig. 2 (a) shows the flow of power from the power supply input to terminal 113a of the 90 ° hybrid circuit 113 to the reflected power output from terminal 113b. Figure 2 (b) shows the output from the re-input to terminal 113 b of the 90 ° hybrid circuit 113. The flow of power up to re-radiation by the radiating element 111 is shown.

Set the power supplied from terminal 119a of switching circuit 119 to 0 dB (reference). This power supply is passed through the terminal 1 1 1b of the switching circuit 1 19 and distributed by the 90 ° hybrid 1 13 in 3 dB units. Each power supply point 1 1 1a, 1 1 1b of the radiating element 1 1 1 Supplied to Then, by being combined on the radiating element 111, the radiating element 111 has approximately O dB (slightly lower than O dB due to heat loss and reflection loss in the radiating element 111). The main circular polarization is emitted.

At the same time, due to the characteristics of the radiating element 111, a counter-rotating circular polarization (cross polarization) equivalent to _30 dB occurs.

On the other hand, due to the mismatch between the radiating element 111 and the transmission line, a reflected power of 123 dB is generated at each of the feeding points 111a and 111b. Their reflected power is 90. The power is combined by the hybrid circuit 113 to produce power of 120 dB, which is output from the terminal 113 b to the terminal 119 c of the switching circuit 119.

However, the terminal 119c of the switching circuit 119 is in the off state, that is, the cutoff state. Therefore, the power of _20 dB is totally reflected and re-input to the terminal 113 b of the 90 ° hybrid circuit 113 as it is, and the respective power supply points 1 1 1 a and 1 1 of the radiating element 1 1 1 Resupplied to 1b. As a result, the radiation power of counter-rotating circularly polarized light (cross polarization) based on the mismatch between the radiating element 111 and the transmission line is -20 dB.

Therefore, the total reverse circularly polarized radiation power of the conventional circularly polarized switching antenna is the radiation power (13 O dB) based on the performance of the radiating element 111 and the radiating element 111 and the transmission line. It is the sum of the radiated power (1 2 O dB) based on the mismatch between the two, and is about -19.5 dB (to be precise, the total inverse circularly polarized radiated power increases or decreases depending on the phase relationship between the two).

Next, the reverse-circularly-polarized radiation power of the circularly-polarized switching antenna shown in FIG. 1 will be described with reference to FIG.

FIG. 3A shows the flow of power from the power supply input to the terminal 13a of the 90 ° hybrid circuit 13 to the reflected power output from the terminal 13b. Figure 3

(b) shows the power flow from re-input to the terminal 13 b of the 90 ° hybrid circuit 13 to re-radiation by the radiating element 11. Here, the power supplied from the terminal 13a of the 90 ° hybrid circuit 13 is set to 0 dB (reference). This power is distributed by the 90 ° hybrid 13 in 13 dB increments, passes through the 180 ° phase shifters 12 a, 12 b, and passes through the power supply points 11 a, 1 1 of the radiating element 11. supplied to b. As in the case of the conventional circularly polarized switching antenna, the radiating element 11 emits a main circularly polarized wave of about 0 dB, and a reverse circularly polarized wave (cross polarization) equivalent to 30 dB. appear.

On the other hand, due to the mismatch between the radiating element 11 and the transmission line, reflected power of 23 dB is generated at each of the feed points 11a and lib. These reflected powers are combined by the 90 ° hybrid circuit 13 and output as one 20 dB power from the terminal 13 to the reflectionless termination 14.

In the circularly-polarized switched antenna shown in Fig. 1, much of this 20 dB power is absorbed by the non-reflective termination 14, and only — 20—20 = —40 dB power is transmitted through the 90 ° hybrid circuit. The signal is re-input to the terminal 13 b of 13 and fed back to the feed points 11 a and 11 b of the radiating element 11. As a result, the radiation power of counter-rotating circular polarization (cross polarization) based on the mismatch between the radiating element 11 and the transmission line is 140 dB.

Therefore, the total counter-rotating circularly radiated power from the circularly polarized switching antenna shown in Fig. 1 is the radiated power (-30 dB) based on the performance of the radiating element 11 alone and the radiating element 11 The sum of the radiated power (-40 dB) due to the transmission line mismatch is about 29.5 dB (to be exact, the total counter-rotating circularly polarized radiated power increases or decreases due to the phase relationship between the two.) ).

Thus, by using the circularly-polarized switching antenna shown in Fig. 1, it is possible to reduce the counter-circularly-polarized radiation power, so that it is possible to obtain a better cross-polarization discrimination degree than in the past.

(Second embodiment)

FIG. 4 is a block diagram showing a configuration of a second embodiment of a circular polarization switching antenna according to the present invention. The circularly-polarized switching antenna shown in Fig. 4 is connected to the 90 ° hybrid circuit 13 terminal 13a of the circularly-polarized antenna shown in Fig. Phase shifter) 16a, 16b, 16c are cascaded. The phase shift amounts of the phase shift circuits 16a to 16c are 90 °, 45 °, and 22.5 °, respectively. is there. Similarly to the phase shift circuits 12a and 12b, the third control signals s23 and s24 from the control circuit (see FIG. 5) described later are also applied to the phase shift circuits 16a to 16c. , s 25, respectively. The state of each of the phase shift circuits 16a to 16c is controlled by control signals s23 to s25, respectively.

In FIG. 4, except for the radiating element 11, the polarization switching is performed by the phase shift circuits 12 a, 12 b, 16 a to 16 c, the 90 ° hybrid circuit 13, and the non-reflection termination 14. Compensator 17 is configured.

As described above, the phase shift circuits 12a and 12b and the 90 ° hybrid circuit 13 can realize the function of the 180 ° phase shift circuit in addition to the function of switching the circular polarization. Therefore, it can be said that the circularly-polarized switching antenna shown in FIG. 4 includes a 4-bit digital phase shifter. Therefore, it is possible to radiate right-handed and left-handed circularly polarized waves with an arbitrary phase of 22.5 ° steps.

Note that the number of phase shift circuits 16 a to 16 c coupled to the terminal 13 a of the 90 ° hybrid circuit 13 is not limited to three. That is, n (n is a natural number) phase shift circuits may be combined.

In this case, the phase shift amount of each phase shift circuit coupled to terminal 13a of 90 ° hybrid circuit 13 is set to 180 ° Z2 ^m . Where m is a different natural number from 1 to n. For example, when n == l, m = l, and the phase shift amount of the phase shift circuit is set to 90 °. Also, when n = 4, m = 1, 2, 3, and 4, and the phase shift amount of each phase shift circuit is set to 90 °, 45 °, 22.5 °, 11.25 °, respectively. . When the phase shift amount of each phase shift circuit is set in this way, the circularly polarized wave switching type antenna includes an n + 1 bit digital phase shifter. Therefore, the radiation phase can be controlled in 360 ° 2 ^{n + 1} steps.

(Third embodiment)

Next, an embodiment in which a phased array antenna is configured by using the circularly polarized wave switching type antenna shown in FIG. 4 will be described.

FIG. 5 is a block diagram showing an overall configuration of a circularly-polarized-switching phased array antenna according to the present invention. The phased array antenna shown in FIG. 5 has M (M is an integer of 2 or more) antenna units 10. Each antenna unit 1 0 Is constituted by the circularly polarized wave switching type antenna shown in FIG.

Each antenna unit 10 is coupled to a distribution combiner (distribution means) 30. The power supply for exciting the radiating element 11 of each antenna unit 10 is given to the distributor / combiner 30. The distributing / combining unit 30 distributes the input power supply to each antenna unit 10 and outputs the same to the polarization switching phase shifter 17 of each antenna unit 10.

The polarization switching phase shifter 17 of each antenna unit 10 is connected to the output side of a control circuit (control means) 20. The control circuit 20 gives the above-described control signals s 21 to s 25 to the phase shift circuits 12 a, 12 b, 16 a to 16 c of each antenna unit 10. . The control signals s2 1 to s25 are combined to form a control signal s2.

This control circuit 20 is formed by a transistor circuit.

The antenna unit 1 is composed of the M antenna units 10, the control circuit 20, and the distributor / combiner 30.

Further, the control circuit 20 is connected to a control device 2 that controls the antenna unit 1. The rotation direction of the circularly polarized wave is set in the control device 2. This setting can be switched.

In the control device 2, the position of the radiating element 11 of each antenna unit 10 and the working frequency are set in advance. Based on the position and the frequency, an optimal phase shift amount for directing the radiation beam in a desired direction is calculated for each of the M antenna units 10. Then, the control data s1 including the polarization direction is added to the calculation result and the control data s1 including the setting switching timing is output to the control circuit 20.

The control circuit 20 includes a logic circuit such as a data distribution circuit and a data latch circuit, and a current source or a voltage source as necessary. The control device 2 and each phase shift circuit included in each antenna unit 10 It is connected to the input side of 12a, 12b, 16a to 16c.

The control circuit 20 drives each of the phase shift circuits 12a, 12b, 16a to 16c with a set value and a switching timing based on the control data s1 input from the control device 2. Distribute and supply a control signal s 2 having a current or voltage sufficient for The state of each of the phase shift circuits 12a, 12b, 16a to 16c changes depending on whether the above-mentioned control signal s2 is "on" or "off". The direction of polarization and the amount of phase shift of the antenna unit 10 are determined according to the state of each of the phase shift circuits 12a, 12b, 16a to 16c.

On the other hand, the distributing / combining unit 30 distributes the input power supply and outputs it to each antenna unit 10. Each antenna unit 10 radiates based on the above-described settings, and a radiation beam is formed in a desired direction.

As described above, the circularly-polarized switched antenna shown in Fig. 4 has excellent cross-polarization discrimination, so a phased array antenna should be constructed using this circularly-polarized switched antenna. Thus, the direction of rotation of circularly polarized waves can be switched, and a phased array antenna with high cross polarization discrimination can be realized.

Here, the case where the phased array antenna is configured using the circularly polarized switching antenna shown in FIG. 4 has been described. However, it goes without saying that a similar effect can be obtained even if a phased array antenna is configured using the circularly polarized switching antenna shown in FIG.

The circularly-polarized-switching phased array antenna having such characteristics can be used, for example, in microwave communication, satellite communication, and a radar device using circularly-polarized light that is used while switching between orthogonally and circularly polarized waves.

Next, the structure of the antenna unit 1 of the circularly-polarized switching type phased array antenna shown in FIG. 5 will be described. FIG. 6 is an exploded view showing the structure of the antenna unit 1. The antenna unit 1 has a multilayer structure as shown in FIG. That is, the parasitic element layer 41, the first dielectric layer 42, the antenna unit layer 43, the second dielectric layer 44, the feeding slot / ground layer (hereinafter abbreviated as the feeding slot layer). The layers 45, the third dielectric layer 46, and the distribution / combination layer 47 are formed in close contact with each other in this order. Each of the above layers 4 :! to 47 is formed by a photolithography technique, an etching technique, a printing technique, or the like during the process, and is multi-layered by lamination or bonding.

A parasitic element 18 is formed on the parasitic element layer 41. FIG. 4 does not show the parasitic element 18. However, by using the parasitic element 18, the band of the antenna can be widened. The parasitic element 18 is connected to the antenna via the dielectric layer 42. The antenna unit 10 (particularly, the radiating element 11) of the tena unit layer 43 is electromagnetically coupled.

For the dielectric layer 42, a dielectric having a relative permittivity of about 1 to 10 such as a printed board, a glass substrate, a ceramic substrate, or a foam material is used. Further, the dielectric layer 42 may be a space (air layer) supported by a spacer or the like.

The antenna unit 10 shown in FIG. 4 is formed on the antenna unit layer 43 (note that the symbol shown in FIG. 6 indicates that the antenna unit 10, that is, the radiating element 11 is partially polarized). Means the combination of the wave switching phase shifter 17).

For the dielectric layer 44, a dielectric having a relative permittivity of about 3 to 12 such as a printed board, a glass substrate, or a ceramic substrate is used. Further, a semiconductor substrate such as Si, GaAs or the like may be used.

A ground conductor plate 31 and a power supply slot 32 are formed in the power supply slot layer 45.

The same material as that of the dielectric layer 44 is used for the dielectric layer 46.

In the distribution / combination layer 47, the distribution / combination unit 30 shown in FIG. 5 is formed. The mixing / mixing device 30 is electromagnetically coupled to the antenna unit 10 of the antenna unit layer 43 via the power supply slot 32 of the power supply slot layer 45.

In FIG. 6, for simplicity, each of the layers 41 to 47 is described separately, but the layers adjacent to the dielectric layers 42, 44, and 46, for example, the parasitic element layer 41 and the coupling The layers 45 and the like can be realized by forming a pattern on one or both sides of the dielectric layer. Further, the dielectric layer does not necessarily need to be formed of a single material, and may have a configuration in which a plurality of materials are stacked.

The parasitic element 18 formed in each layer, the antenna unit 10, the data latch circuit included in the control circuit 20, and the feeding slot 32 are two-dimensionally arranged in a triangular arrangement. By thus arranging the antenna units 10 and the like two-dimensionally, two-dimensional electronic scanning in the beam direction can be performed.

However, the present invention is also effective with a phased array antenna having a one-dimensional array, and the present invention is also effective with an array other than a triangular array, for example, a square lattice array. Also, the lamination structure and the interlayer coupling means shown in FIG. Even so, the present invention is effective.

For example, in FIG. 6, the distributor / synthesizer 30 and the antenna unit 10 are coupled via the power supply slot 32, but the distributor / synthesizer 30 and the antenna unit 10 are connected to the power supply pins or the like. They may be connected by other power supply coupling means, or the distributor / combiner 30 and the antenna unit 10 may be formed in the same layer.

Further, the distributor / synthesizer 30 need not be a strip line branch circuit as shown in FIG. 6, but may be another form such as a radial waveguide.

Further, in FIG. 6, the radiating element 11 and the polarization switching phase shifter 17 are formed on the same layer in the antenna unit layer 43, but the radiating element 11 and the polarization switching phase shifter 17 are separated. It is also possible to form them on different layers and stack them, and connect them with a power supply coupling means such as a power supply slot or a power supply pin.

Next, the antenna unit layer 43 shown in FIG. 6 will be further described. FIG. 7 is a plan view showing the arrangement of one antenna unit 10 formed on the antenna unit layer 43. FIG.

The 90 ° hybrid circuit 13 shown in FIG. 7 is a branch line type hybrid circuit. The branch line type hybrid circuit has a substantially square ring shape. When the wavelength of the power supply is λ, the length of one side of the branch line hybrid circuit is about 4. The four corners of the branch line type hybrid circuit are terminals 13a to 13d, respectively.

A strip line 55 a including a gap (cut portion) is formed between the feed point 11 a of the radiating element 11 and the terminal 13 c of the 90 ° hybrid circuit 13 _c . A strip line 55b including a gap is formed between a feed point 11b of the element 11 and a terminal 13d of the 90 ° hybrid circuit 13. Further, a strip line 55c is formed from the terminal 13a of the 90 ° hybrid circuit 13 to a position on the glass substrate 50 corresponding to the power supply slot 32 shown in FIG. Have been.

Distributed strip lines such as microstrip lines, triplate lines, coplanar lines and slot lines are used for these strip lines 55a to 55c. The phase shift circuits 12a and 12b are switched line type phase shifters. That is, strike Strip lines 51a and 51b having different lengths are arranged on both sides of the lip lines 55a and 55b, respectively, and two lines are provided between the strip lines 55a and 55b and the strip line 51a. Two microwave switches 52b are arranged between the strip lines 55a, 55b and the strip line 51b. By switching these microwave switches 52a, 52b to "ON" or "OFF J" and selecting one of the strip lines 51a, 51b as a signal path, the phase shift circuit 12a, It is possible to control the passing phase of 1 2 b.On the other hand, the phase shifters 16 a to l 6 c are loaded line type phase shifters, that is, two strip lines 51 c are approximately 4 The two microwave switches 52c connect each stripline 51c to another stripline 51d open at the end, apart from the stripline 55c. By switching both microwave switches 52 c so that they are both “on” or “off” and changing the susceptance of the phase shift circuits 16 a to 16 c, the passing phase is changed. Can be changed.

As the strip lines 51a to 51d, for example, distributed constant circuits such as a microstrip line, a triplate line, a coplanar line, and a slot line are used. As the microwave switches 52a to 52c, for example, a micromachine switch, a PIN diode switch, a HEMT switch, or the like is used.

Generally, when the phase shift amount is large, the switched line type has better electrical characteristics. When the phase shift is small, the loaded line type has better electrical characteristics. For this reason, a switched-line type is used here for the 180 ° phase shift circuits 12a and 12b. Loaded line types were used for the 90 °, 45 °, and 22.5 ° phase shift circuits 16a to 16c. However, it is also possible to use a switched line type for all the phase shift circuits 12a, 12b, 16a to 16c.

In addition, a phase shift circuit other than the load line type or the switched line type such as a reflection type may be used for the phase shift circuits 12a, 12b, 16a to 16c.

The microwave switches 52 a to 52 c included in each of the phase shift circuits 12 a, 12 b, and 16 a to 16 c are connected to the control circuit 20 via the control line 21.

The four microwave switches 52a and 52b included in the phase shift circuit 1 2a are controlled by Operated by the control signal s21 output from the circuit 20, the passing phase can be controlled as described above. The same applies to the phase shift circuit 12b.

Also, the two microwave switches 52 c included in the phase shift circuit 16 a operate simultaneously by the control signal s 23, and can change the passing phase as described above. The same applies to the phase shift circuits 16b and 16c.

By changing the passing phase of each of the phase shift circuits 12a, 12b, 16a to 16c in this way, the power supply phase to the radiating element 11 can be changed.

Industrial applicability

The circularly polarized wave switching type antenna and the circularly polarized wave switching type phased array antenna according to the present invention can be applied to, for example, microwave communication, satellite communication, radar devices using circularly polarized waves, etc., used while switching between orthogonal circularly polarized waves. Can be used.

Claims

The scope of the claims

(1) a radiating element having two feeding points and emitting two linearly polarized waves orthogonal to each other;

A first and second phase shifter connected to each feed point of the radiating element and having a phase shift of 180 °; and a first and second phase shifter that divides an input signal into two at a phase difference of 90 °. 90 ° hybrid circuit connected to the

Control means for controlling the amount of phase shift of the first and second phase shifters to 0 ° or 180 ° to emit right-handed or left-handed circularly polarized waves from the radiation element;

A circularly polarized switching antenna.

(2) a radiating element having two feed points and emitting two linearly polarized waves orthogonal to each other;

A 90 ° hybrid circuit having four terminals and supplied with power for exciting the radiating element to the first terminal;

A non-reflective termination coupled to the second terminal of the 90 ° hybrid circuit; one end coupled to one feed point of the radiating element and the other end coupled to the third terminal of the 90 ° hybrid circuit; A first phase shifter coupled to the first phase shifter and having a phase shift of 180 °;

—A second phase shifter having one end coupled to the other feed point of the radiating element and the other end coupled to the fourth terminal of the 90 ° hybrid circuit and having a phase shift of 180 °. When,

A circularly polarized wave switching type antenna comprising:

(3) In claim 1,

N (n is a natural number, m is a different natural number from 1 to n) third shifters cascaded to the 90 ° hybrid circuit and controlled by the control means so that the phase shift amount is 180 ° Circularly polarized wave switching type antenna further comprising a phaser Na.

(4) In claim 1,

The control means may switch both the phase shift amounts of the first and second phase shifters to 0 ° or 180 ° as the polarization radiated from the radiating element, and thereby change the circular polarization in the first rotational direction. And the phase shift amounts of the first and second phase shifters are switched to 0 °, 180 ° or 180 °, and 0 °, respectively, to change the circular polarization of the first rotation direction and reverse rotation. A circularly-polarized switching antenna characterized in that it is generated.

(5) In claim 1,

The said 1st and 2nd phase shifters are switched line type phase shifters, The circularly polarized wave switching type antenna characterized by the above-mentioned.

(6) In claim 3,

The circularly polarized wave switching type antenna, wherein the third phase shifter is a loaded line type phase shifter.

(7) a radiating element having two feeding points and emitting two linearly polarized waves orthogonal to each other;

With

A plurality of radiating elements, first and second phase shifters, a 90 ° hybrid circuit, and a plurality of control means, each of which is arranged in an array; .

(8) a radiating element having two feed points and emitting two linearly polarized waves orthogonal to each other;

A non-reflective termination coupled to the second terminal of the 90 ° hybrid circuit; A first phase shifter having one end coupled to one feed point of the radiating element and the other end coupled to the third terminal of the 90 ° hybrid circuit, and having a phase shift of 180 °; ,

A second phase shifter having one end coupled to the other feed point of the radiating element and the other end coupled to the fourth terminal of the 90 ° hybrid circuit and having a phase shift of 180 °; ,

Control means for controlling the amount of phase shift of the first and second phase shifters to 0 ° or 180 ° so as to emit right-handed or left-handed circularly polarized waves from the radiating element. A plurality of

A circularly polarized phase-shifted phased array antenna, wherein the units are arranged in an array.

(9) In claim 7,

N (n is a natural number, m is a different natural number from 1 to n) third cascadedly coupled to the 90 ° hybrid circuit and controlled by the control means so that the phase shift amount is 180 ° Z2 ^m A phase-shifted circularly-polarized switched array antenna further comprising:

(10) In claim 7,

The control means may switch both the phase shift amounts of the first and second phase shifters to 0 ° or 180 ° as the polarization radiated from the radiating element, and thereby change the circular polarization in the first rotational direction. And the phase shift amounts of the first and second phase shifters are switched to 0 °, 180 ° or 180 ° and 0 °, respectively, to generate circularly polarized waves having the first rotation direction and reverse rotation. This is a phased array antenna with circular polarization switching.

(1 1) In claim 7,

The said 1st and 2nd phase shifters are switched line type phase shifters, The circularly polarized wave switching type phased array antenna characterized by the above-mentioned.

(1 2) In claim 9,

The third phase shifter is a single-ended deadline type phase shifter, wherein a circularly polarized wave switching type phased array antenna is provided.

(1 3) In claim 8, The above-mentioned units are two-dimensionally arranged, and are a circularly polarized wave switching type phased array antenna.

(14) In claim 8,

A circle having a multilayer structure including a layer on which the radiating element included in each unit is formed, and a layer on which the first and second phase shifters included in each unit are formed. Polarization switching type phased array antenna.

(15) In claim 8,

A distribution unit that distributes the power supply to the 90 ° hybrid circuit included in each unit;

A circular polarization switching type phased device having a multilayer structure including a layer in which the first and second phase shifters included in each unit are formed, and a layer in which the distribution unit is formed. Array antenna.