JPS5826844B2 - variable phase attenuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable phase attenuator that can simultaneously change the phase and amplitude of microwaves.

In a microwave radio communication number ζ, where two orthogonal polarized waves are used at the same time and at the same frequency, the orthogonal relationship between the two polarized waves disappears due to the anisotropy of the propagation space, and the two polarized waves cross each other. There is a problem of polarization and interference.

Now, considering the case where orthogonal bivalent waves V and H are radiated from the transmitting antenna, the two receiving terminals for the orthogonal bivalent waves on the receiving antenna side have V1+AH and H1+A, respectively.
The V wave is split.

here, ■1 is ■polarization component Hl is H polarization component AH is ■Polarized wave componentH polarized wave component included in the receiving wave terminal AV is the H polarization component ■Polarization component included in the receiving wave terminal It is.

■To eliminate the H polarization component AH, which is an interference wave with respect to H polarization component AH, take out a part of the H polarization component H1 in the other reception wave terminal with the same amplitude and opposite phase to the H polarization component AH. This can be coupled to the receiving wave terminal on the side through which the (1) polarized wave component (1) and the H polarized wave component (AH) are propagating.

To configure a circuit with such a function in the microwave band, a variable phase shifter and a variable attenuator are required, and conventionally the first phase shifter and variable attenuator are required.
It was configured as shown in the figure.

That is, in FIG. 1, 1 is a rectangular waveguide, 2 is a dielectric plate movable in the X-axis direction, 3 is a rectangular/circular waveguide converter, 4 is a circular waveguide, and 5 is two orthogonal waveguides. a 180-degree retardation plate made of a dielectric material that delays the phase of one of the polarized waves by 180 degrees; 6 is a coupling hole provided in the circular waveguide 4 for extracting a wave polarized in the y-axis direction; 7; is the circular waveguide 4
A coupling hole for extracting waves polarized in the X-axis direction,
8 is a branch waveguide connected through the coupling hole 6, 9 is a branch waveguide connected through the coupling hole 7, and 10 is composed of the rectangular waveguide 1 and the dielectric plate 2. A variable phase shifter 11 is connected to the coupling hole 6. A polarization splitter consisting of a coupling hole 7, a branch waveguide 82, and a branch waveguide 9; 12 is a rotary joint (rotation mechanism) for rotating the circular waveguide 4 having the 180-degree retardation plate 5 therein; circular waveguide for connection).

Next, it will be explained that the circuit shown in FIG. 1 functions as a variable phase shifter and a variable attenuator.

Now, consider the case where linearly polarized waves are incident on the rectangular waveguide 1.

When the position of the dielectric plate 2 is moved in the direction shown by the arrow in FIG. 1, the effect of the dielectric plate 2 on the electric field of the incident wave changes.

Therefore, the wavelength within the rectangular waveguide 1 into which the dielectric plate 2 is inserted changes, and the phase velocity of the wave changes.

Therefore, if the position of the dielectric plate 2 is changed, the dielectric plate 2
The inserted rectangular waveguide 1 functions as a variable phase shifter 10.

The wave that has passed through the variable phase shifter 10 is converted into a fundamental mode wave of the circular waveguide 4 by the rectangular/circular waveguide converter 3.
It passes through the 0 degree retardation plate 5.

The operation of this 180-degree retardation plate 5 will be explained with reference to the operation principle diagrams shown in FIGS. 2a and 2b.

The polarization plane of the electric field of the wave incident on the circular waveguide 4 in FIG. 1 is in the y-axis direction.

This incident wave is shown as E in FIG. 2a.

If the 180-degree retardation plate 5 is tilted by θ with respect to the It can be divided into E.

Therefore, when the wave passes through the 180-degree retardation plate 5, the phase of only the wave E'' is delayed by 180 degrees, and the relationship with the wave E'' changes from that shown in FIG. 2A, as shown in FIG.

Therefore, the wave E'' after passing through the 180-degree phase difference plate 5 and the wave E
The composite wave with is E.

It is tilted by an angle of 2θ with respect to the y-axis as shown in FIG.

That is, by rotating the 180-degree retardation plate 5 around the tube axis of the circular waveguide 4, the plane of polarization of the wave after passing through the iso-degree retardation plate 5 can be changed.

Next, wave E is polarized by an angle of 20 from the y-axis.

Let us consider the case where the polarization beam is incident on the polarization splitter 11.

The polarization splitter 11 has a function of splitting only waves polarized in the y direction into the branch waveguide 8 and only waves polarized in the X direction into the branch waveguide 9.

Therefore, as described above, when a wave polarized by an angle of 2θ from the y-axis is incident, only the power given by the first equation with respect to the incident wave is extracted to the branch waveguide 8, for example.

Here, Pxo is the power taken out to the branch waveguide 8, and Pi is the power of the incident wave.

. Therefore, if the 180-degree retardation plate 5 and the polarization splitter 11 are connected via the mutually rotatable rotary joint 12 and the rotation angle of the 180-degree retardation plate 5 is changed, the branched guide will be generated in accordance with the rotation angle. Attenuation can be given to the waves taken out to the wave tube 8.

In this case, the power taken out to the branch waveguide 9 may be absorbed by providing a non-reflection terminator or the like.

As mentioned above, the conventional variable phase attenuator is constructed by moving the variable phase shifter, the variable attenuator, the dielectric plate 2 in the rectangular waveguide 1, and the 180-degree phase difference plate 5 in the circular waveguide 4. I was getting it.

However, in order to change the phase, the dielectric plate 2 of the variable phase shifter 10 is
This is obtained by changing the phase velocity of the rectangular waveguide 1, that is, the cutoff frequency, by moving the
The frequency characteristics of the variable phase shifter 10 are so strong that it is difficult to obtain good characteristics over a wide band.

Further, when driving the dielectric plate 2 of the variable phase shifter 10 with a servo motor or the like, it is necessary to convert rotational motion to linear motion, resulting in a complicated drive mechanism and low reliability.

This invention was made to eliminate these drawbacks, and combines two 90-degree retardation plates, a 180-degree retardation plate, and a polarization demultiplexer to widen the characteristics.
The present invention provides a variable phase attenuator that integrates a phase shifter and an attenuator with a simple drive mechanism.

This invention will be explained in detail below.

Figure 3 shows an embodiment of the present invention.
, 5, 8, 9, 11 and 12 are the same as in FIG.

Reference numeral 13 denotes a 90-degree phase difference plate made of a dielectric plate that delays the phase of only one of the orthogonal polarized waves by 90 degrees, and both are provided in the circular waveguide 4.

Next, the operation of the actual case shown in FIG. 3 will be explained with reference to FIG.

Now, the incident wave polarized in the y-axis direction is E, and the 90-degree phase difference plate 13 on the side of the rectangular/circular waveguide converter 3 has a phase difference of 45 degrees and 180 degrees with respect to the y-axis as shown in the figure. Plate 5 (45-
Φ) degree, and further a 90 degree phase difference plate 13 on the polarization splitter 11 side.
When the waves are tilted by (45 + θ) degrees, the wave after passing through them is given by the following equation, where E is the incident wave.

That is, here, Eoy-EoX is the transmitted wave component e in the y direction and the x direction, respectively, the amplitude ω of the incident wave is the angular frequency t, and the time β is the phase delay determined by the circuit length.

Therefore, when the branch waveguide 8 is aligned with the X axis, the wave taken out into the branch waveguide 8 becomes Eoy, which has a power ratio given by the following equation with respect to the incident power.

Therefore, by rotating the phase difference plate 13 by 90 degrees, the attenuation can be changed.

Further, as is clear from equation (3), the phase also changes by (2Φ+θ) with respect to Φ and θ.

Therefore, in the circuit configuration of FIG. 3 according to the present invention, 1
The phase and attenuation amount can be changed at the same time only by rotating the circular waveguide 4 which has the 80-degree retardation plate 5 and the 90-degree retardation plate 13 inside, so when driven by a servo motor etc. The mechanism becomes simpler.

Also, as is well known, 90 degree retardation plate 13.18
Since the 0-degree phase difference plate 5 can easily obtain broadband performance compared to the rectangular waveguide type variable phase shifter 10, it is easy to obtain a wideband variable phase attenuator.

In addition, in the above description, the polarization splitter 11 is explained using one having an orthogonal bifurcated waveguide, but the shape of the polarization splitter 11 is not limited to this, and it is possible to separate orthogonal bivalent waves. Anything is fine.

In addition, we have explained using examples of a 90 degree retardation plate and a 18080 degree retardation plate in which a dielectric plate is inserted into a circular waveguide.
These retardation plates can also be obtained by a combination of a circular waveguide and a capacitive frame, a combination of a circular waveguide and a resonator, etc., and these may also be used.

As explained in detail above, the variable phase attenuator of the present invention can change the phase and attenuation amount by rotating the 90-degree phase difference plate and the 180-degree phase difference plate, so the rotation mechanism is simple and reliable. becomes more sexual.

Further, since it can be constructed by combining circuits that can easily achieve a wide frequency characteristic, there is an advantage that the overall characteristic can be made wide band.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a conventional variable phase attenuator, FIGS. 2 a and b are explanatory views showing the operating principle of a 180-degree phase difference plate, and FIG. 3 is a perspective view showing an embodiment of the present invention. 4 are explanatory diagrams of the operation of this invention. In the figure, 1 is a rectangular waveguide, 3 is a rectangular/circular waveguide converter,
4 is a circular waveguide, 5 is a 180-degree phase difference plate, 11 is a polarization splitter, 12 is a rotary joint, and 13 is a 90-degree phase difference plate. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A polarization demultiplexer that can separate two orthogonal polarized waves, and a 90-degree delay in the phase of only one polarized wave of the orthogonal dual-valued waves.2
a 180-degree phase difference plate that delays the phase of only one polarized wave of the orthogonal bivalent waves by 180 degrees;
It consists of a rectangular waveguide/circular waveguide converter and a connecting circular waveguide having a rotation mechanism, and a first 90 degree retardation plate is provided on the circular waveguide side of the rectangular/circular waveguide converter. The rotation mechanism is connected to generate circularly polarized waves, and the 180-degree retardation plate, the second 90-degree retardation plate, and the polarization splitter are connected to the first 90-degree retardation plate in sequence. A variable phase attenuator, characterized in that the variable phase attenuator is connected via a connecting circular waveguide having a connecting circular waveguide.