JPS6322721Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microstripline diode phase shifter.

FIG. 1 shows an example of a conventional microstripline diode phase shifter. This phase shifter branches the first and second stub circuits 4 and 5 by setting an electrical angle of θ ₀ (approximately 90°) to the input/output line 3 that connects the microwave input/output terminals 1 and 2. Diodes 6 and 7 are connected in series to each stub circuit 4 and 5 with their anodes facing the input/output line 3 side, and the tips of each stub circuit 4 and 5 are connected to the input/output line 3 side. The structure is such that a bias terminal 8 is connected via a low-pass wave generator 9.

Note that in this application, the input/output line refers to a line through which microwaves subjected to phase shift processing pass.

The phase angle of such a microstrip diode phase shifter is determined by the difference between the phase angle of the transmission coefficient from terminal 1 to terminal 2 when each diode 6, 7 is forward biased and the phase angle of the transmission coefficient from terminal 1 to terminal 2 when each diode is reverse biased.

In such a diode phase shifter, when the microwave input from terminal 1 or terminal 2 leaks into bias terminal 8, the characteristics as a phase shifter deteriorate. Conventionally, in order to prevent this leakage, the bias terminal 8 was connected to the input/output line 3 via a low-pass wave generator 9 as shown in the figure, or via a lumped constant element (coil) with a very large impedance. The bias terminal 8 was connected to the input/output line 3.

However, the former structure has the disadvantage that the circuit becomes large. Furthermore, the latter structure has the disadvantage that stable characteristics cannot be obtained depending on the connection position and connection method of the lumped constant elements.

An object of the present invention is to provide a microstripline type diode phase shifter that can prevent microwaves from leaking into the bias terminal without increasing the size or deteriorating the characteristics.

In the present invention, a high frequency open/DC short circuit is branch-connected to the input/output line, a stub circuit having a diode is connected in pairs in the middle of the input/output line, and a high frequency short/DC short circuit is connected to the terminal of each stub circuit.
In a microstripline diode phase shifter, each of which is provided with a DC cutoff portion and has a bias supply circuit connected to each of the stub circuits, the bias supply circuit connects the diode of each of the paired stub circuits to the high frequency short circuit. The bias supply circuit includes an interconnection line portion that interconnects each connection point with the DC cutoff portion, and a common line portion that connects the intermediate point of the interconnection line portion and the bias terminal, and each of the connections of the bias supply circuit. The bias supply circuit is characterized in that the impedances seen from each of the points to the intermediate points are determined to have a magnitude such that the bias supply circuit functions as a band-stop reactor.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows a first embodiment of the present invention. The microstripline diode phase shifter of this embodiment has a θ ₀
The first and second stub circuits 4 and 5 are connected as a pair with an electrical angle of about 90 degrees separated, and diodes 6 and 7 are connected to the square stub circuits 4 and 5, respectively, and their cathodes are connected to input/output lines. 3, and the anode sides of the diodes 6 and 7 are respectively grounded via capacitors 10 and 11 forming a high frequency short circuit/DC cutoff section. Paired first and second
A common bias supply circuit 12 is connected to the anode sides of the diodes 6 and 7 of the stub circuits 4 and 5, and a bias is applied to each of the diodes 6 and 7 from the bias terminal 8. The bias supply circuit 1
2 is a pair of first and second stub circuits 4 and 5;
diodes 6 and 7 and high frequency short circuit/DC cutoff section 1
0 and 11, and a common line portion 12B that connects the intermediate point b of the interconnection line portions and the bias terminal 8. . Further, the impedances of the bias supply circuit 12 when viewed from the connection points a and c to the intermediate point b are determined to be such that the bias supply circuit 12 functions as a band-stop reactor. With the provision of the bias supply circuit 12 in this manner, the input/output line 3 is grounded by a λ/4 grounding wire 13 that forms a high frequency open/DC shorted portion.

Such a microstripline type diode phase shifter is shown in FIG. 3 as a four-terminal circuit. In addition, L is the reactance of the bonding wire that occurs during mounting, θ ₁ is the electrical angle between points b and a and between points b and c of the bias supply circuit 12, and θ ₂ is the b of the bias supply circuit 12. θ ₃ is the electrical angle of the grounding wire 13 of λ/4, and Z ₁ is the characteristic impedance of the line between points b and a and between points b and c of the bias supply circuit 12. ,
Z ₂ is the characteristic impedance of the open line between point b of the bias supply circuit 12 and the bias terminal 8, and Z ₃ is the characteristic impedance of the short-circuited line at the end consisting of the ground line 13.

Now, in such a circuit, terminals 1 and 1'
In order to avoid the influence of the bias supply circuit 12 during the process in which the microwave input from the stub circuits 4 and 5 are output to the terminals 2 and 2', it is necessary to move the microwaves from points a and a' to b and b. It is only necessary to make the impedance sufficiently large when viewed from point '' and from point c, c' to point b, b'. That is, L, Z ₁ , Z ₂ , θ ₁ , and θ ₂ may be determined to have the impedance shown in FIG. 4. In other words, the bias supply circuit 12 may be formed of a band-stop reactor. In addition, in Fig. 4, ₁ and ₂ are the lower and upper limit frequencies of the microstripline diode phase shifter, ₀ is the center frequency, and Z is the distance from points a and a' to b,
This is the impedance when looking at point b'.

Although the above embodiment describes the case where the present invention is applied to a low date line type microstripline type diode phase shifter, the present invention is not limited to this, and can also be applied to a directional coupler. The present invention can be similarly applied to reflective microstripline diode phase shifters and the like.

FIG. 5 shows an example of a microstripline type diode phase shifter on the reflective side using this directional coupler. Note that parts corresponding to those in FIG. 2 are designated by the same reference numerals. In this embodiment, a branch line type directional coupler 14 with 3 dB coupling is connected in the middle of the input/output line 3 as shown in the figure.

In such a reflective microstripline diode phase shifter, the microwave input from terminal 1 is divided by 1/2 by the directional coupler 14.
and is supplied to the first stub circuit 4 connected to the coupling end of the directional coupler 14 and the second stub circuit 5 connected to the pass-through end.
The first and second stub circuits 4 and 5 supplied with microwaves are replaced as impedance elements having a unique phase angle depending on the direction (forward direction, reverse direction) of the bias applied to the diodes 6 and 7. The reflected waves reflected by the stub circuits 4 and 5 as impedance elements return to the directional coupler 14 again, are combined, and are output to the terminal 2.

The phase angle of such a reflective microstrip line diode phase shifter is determined by the difference in phase angle of the transmission coefficient from terminal 1 to terminal 2 when forward biased and when reverse biased, similar to the above-mentioned rhodated line type microstrip line directional coupler.

As explained above, in the microstripline diode phase shifter according to the present invention, the bias supply circuit is constructed with a band-stop reactor, so that microwaves can be prevented from leaking into the bias terminal without increasing the size. can be prevented. Therefore, according to the present invention, it is possible to provide a microstripline type diode phase shifter that is small and has stable characteristics.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional diode phase shifter. Fig. 2 is a circuit diagram showing an example of a low date line type diode phase shifter according to the present invention; Fig. 3 is a circuit diagram showing the circuit of Fig. 2 as a four-terminal circuit;
The figure is a frequency characteristic diagram of the bias supply circuit in this embodiment, and FIG. 5 is a circuit diagram showing an example of a reflective type diode phase shifter according to the present invention. 1, 2... terminal, 3... input/output line, 4, 5
...Stub circuit, 6,7...Diode, 8...
Bias terminal, 10, 11... Capacitor, 12
...Bias supply circuit, 12A...interconnection line section, 12B...common line section.

Claims (1)

[Scope of utility model registration request] A high-frequency open/DC short-circuit part is branch-connected to the input/output line, a stub circuit having a diode is connected in pairs in the middle of the input/output line, and a high-frequency short-circuit/DC cut-off part is connected at the end of each stub circuit. A microstripline diode phase shifter is provided, in which a bias supply circuit is connected to each of the stub circuits, and the bias supply circuit connects the diodes of each of the stub circuits and the high frequency short circuit/DC cutoff section in pairs. an interconnection line portion that interconnects each connection point, and a common line portion that connects an intermediate point of the interconnection line portion and a bias terminal, and from each of the connection points of the bias supply circuit to the intermediate point. A microstripline type diode phase shifter, characterized in that the impedance of each of the bias supply circuits is determined to have a size such that the bias supply circuit functions as a band-stop reactor.