JPS60206203A - Branching filter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Summary of the Invention> A duplexer for separating high frequency signals of both parts,
It has a small size, low insertion loss, and high frequency and polarization separation. Therefore, it is suitable for use as a branching filter for ground stations in satellite communications.

(Industrial Application Field) The present invention relates to a duplexer for separating high frequency signals of both parts.

This branching filter consists of two 3 dB couplers and a band-elimination filter inserted between them, and a signal in a certain frequency band among the signals input to the first 3 dB coupler is reflected. All other remaining frequency band signals are passed. In such a wave means, the mutual relationship of amplitude and phase between signals belonging to two frequency bands must not be changed.

The device according to the present invention is related to the field of communications, and particularly to the field of satellite communications. This is an illumination system for ground station antennas (in literature, “FEE
This is one element of the antenna (known as ``D''). Also, as is well known, it is expensive to use double large antennas for -C, so this type of antenna is This is a frequency regeneration technique commonly used in the communications field.

Although the present invention will be explained from beginning to end by taking a linearly polarized signal as an example, it is naturally applicable to a communication system using a circularly polarized signal.

As is well known, a linearly polarized signal can be converted into a circularly polarized signal (or vice versa) using a 90'' differential phase shifter (polarizer), which It has a differential phase shift axis that makes an angle of 456 to the signal.

The following is also well known. That is, there are four channel groups in the waveguide connected to the antenna. Two of these are transmission channel groups, and although they have the same frequency, their respective polarizations are different from each other. The remaining two are a reception channel group, which operate at the same frequency, but in a different frequency band from the transmission channel group, and have different polarizations. Frequency separation is required to separate the transmit channel from the receive channel. This separation is based on polarization and using orthogonal mode converters (OM
T: orthogonal-mode trans
ducers) or other means well known to those skilled in the art. In satellite system equipment such as the so-called "OdB" combiner, in addition to separating two frequency bands, it extracts one channel of the two separated bands for each polarization and outputs different outputs. It is also necessary to supply

A double OdB coupler consists of one central waveguide (with a circular or rectangular cross section) and four lateral waveguides, through which image frequency signals for each polarization can propagate. and the lateral waveguides are arranged symmetrically with respect to the central waveguide and exist on one of the two wavefronts with respect to the central waveguide via a plurality of coupling waveguides. Connected so that signals can pass through. The signals existing within the central waveguide are thus separated for each polarization. Each pair of lateral waveguides is arranged symmetrically with respect to the central waveguide, with one pair receiving vertically polarized signals and the other pair receiving horizontally polarized signals (generally speaking, For example, one pair of transverse waveguides receives signals belonging to one plane of polarization, and the other pair receives signals belonging to a plane of polarization perpendicular to that plane).

Each coupling waveguide transfers a portion of the energy of the signal present in the central waveguide into the lateral waveguides.

The signal can be propagated within the coupling waveguide by suitably sizing the coupling waveguide, so that the energy is completely transferred from the central waveguide to the lateral waveguides. be done. Two operating modes can be realized in the coupling waveguide based on so-called alternation. That is, two signals with equal amplitude and phase are transmitted to opposite pairs of lateral waveguides, and they are added together by being transmitted as a whole to the central waveguide.

Coupling waveguides can also be configured as low-efficiency high-pass filters; if the receive band is sufficiently far from the transmit band, the two bands can be separated by choosing the dimensions and shape of the coupling waveguide. Can be separated from each other. This ensures that only the highest frequency band (for example the transmission band) propagates, while the other band propagates unhindered in the central waveguide.

<Prior art> +a) “Circuit for separating two ultra-high frequency signal bands of dual polarization” (Italian patent application Na22821 A/81.
July 9th, 19B1 CAVALIE III D'0
) to) d) describes an OdB combiner that can separate the receive and transmit bands even if these two bands are quite close to each other.

Such a degree of frequency separation is achieved that it is possible to use an OdB coupler in only one of the two bands, but this requires a blocker placed on one wall of each lateral waveguide facing the coupling waveguide. This is due to the cavity. However, this blocking cavity can only operate in a very narrow band. This limits the use of the device described in this Italian application.

This is because when very broadband band rejection is required, the cavity creates such a different phase relationship in the lateral waveguide that the coupling waveguide can no longer be used normally. .

(bCircuit for separating two ultra-high frequency signal bands of dual polarization) (-fThalia patent application Na19845 A/82.
February 25th, 1982 CAVALIERI D'0R
According to O-VITA), the following circuit is described. That is, the circuit can be inserted between the 3 dB combiner via a bandpass filter to separate the stop band from the transmission band. However, since a corrugated device having a thin plate-like structure is used, the device configuration becomes complicated. Moreover, if the stop band is very close to the transmit band, the desired degree of isolation cannot be achieved.

<Problem that the invention seeks to solve> The above conventional technology has the following disadvantages.

・Insertion loss is large (the degree of blocking inside the filter is maximized).

・It has a cumbersome structure and is heavy.

・It has a very complicated configuration.

- It is difficult to use the device in wide and mutually close bands.

<Means for Solving the Problems> The present invention aims to solve the above problems, and provides a circuit that only separates the frequency bands of high-frequency signals in two polarized waves. , both bands corresponding to the two polarized waves (■ and H in Figure 16)
), and four lateral waveguides arranged symmetrically with respect to the central waveguide and connected via a plurality of coupling waveguides, and are identical. a first dual 3 dB coupler that passes signals in both bands of polarization; a wave structure of a band-pass blocking type or a high-pass type that passes only signals in one band; and a second 3 dB coupler having the same configuration as the first 3 dB coupler; Each component is cascaded.

Operation The device is based on a double OdB coupler, which consists of two identical sections (double 3clB couplers) arranged in sequence. Each section has a filtering element of band-pass or high-pass type between it. Therefore, it is possible to separate the two frequency bands even if the respective frequency bands are wide-band, or even if the bands are close to each other.

<Embodiment> FIG. 1 is a structural diagram showing an example of the configuration of a duplexer based on the present invention. In the figure, the configuration of each part is as follows.

1: Flange 2: Connection hole used to connect with other parts of the illuminator 3: Lateral (rectangular) waveguide 4: Central waveguide 5: Polygonal structure (one that can reduce the weight of the device) ) 6: Wave structure diagram (high-pass filter) equipped with a cathoto-off waveguide and a receiving band (high-pass filter) lO: First 3dB coupler 12: Second 3dB coupler 16: Cassotooff waveguide 17: filter Wave section 18: Coupling waveguide The meanings of other reference numbers will be explained later.

FIG. 2 is a block diagram showing the configuration of a circuit for single polarization (V or H), and the configuration of each part in this figure is as follows.

8: Receiving end 9: Transmitting/receiving shared waveguide 11: High-pass filter 13: Transmitting boat 14: High frequency terminal Figure 3 is a diagram for explaining the principle of operation during band pass, and Figure 4 FIG. 2 is a diagram for explaining the principle of operation during bandpass blocking. It should be noted here that the dual 3dB combiner also has two modes of operation. That is, the energy of the magnetic field applied to each input of a pair of lateral waveguides is distributed to the lateral waveguides as well as to the central waveguide.

The device according to the present invention contributes to the realization of a circuit that performs frequency separation and polarization separation of high-frequency signals. According to the embodiment of FIG. 2, the receiving end 8 and the transmitting end 13 responsible for receiving and transmitting, respectively, are not coupled to each other. On the other hand, the signal in the frequency band Tx sent from the Baud H3 is sent to the antennae 5. Frequency band Rx received by antenna 15
is inserted into the receiving end 8.

According to this diagram, only one polarization (for example, V polarization in Figure 1) is mentioned, and that V polarization is completely different from the other polarization (H polarization in Figure 1). Separated (
isolation >35dB).

These features are a result of the symmetrical structure of the device. FIG. 3 is a diagram illustrating an operating mode with such a structure and at a frequency that can pass through the filter. On the other hand, as already mentioned, FIG. 4 schematically shows the operating mode performed under frequencies whose passage is blocked by the filter.

For ease of explanation, the amounts of attenuation and phase shift introduced in the dual 3 dB combiner and filtering section 17 as well as the angle of reflection (the reflected signal has the same amplitude and phase as the incident signal) are both zero. I assumed that. In practice, however, both the coupler and the filtering section change or are capable of changing the amplitude and/or phase of the transmitted and/or reflected signal.

Referring to FIG. 3, the unit amplitude (11 signals applied to
(The C signal is more advanced than the Co signal.) These signals pass through a filtering section (not shown as it is transparent in this case) to a second coupler I2.
and D''. Now, due to the superposition effect, all of the signal applied to B is valid at the exit E' of the lateral waveguide, while none at the exit E of the central waveguide 4. No signal appears.Referring again to Figure 1, two identical frequency signals within the frequency band that can pass through the filter section are:
The signals are extracted from the outputs of two pairs of lateral waveguides in the second coupler 12 according to their respective polarizations.

According to FIG. 4, the filter section is short circuited (C).

C,). This is because the filter works in the pass-stop band. The unit amplitude signal applied to B produces two signals at the outputs C and C'' of the first coupler 1o, each with an amplitude of 1/4 and a phase shift of π/2 with respect to each other. Both signals are reflected off the short circuit and returned to the second coupler (no phase shift is applied to these signals, as mentioned above), where, due to superposition effects, all of the signals applied to B are becomes valid at output B'.

After all, according to the device of the present invention, the transmission band can be separated from the reception band for each of the two polarized waves orthogonal to the four rectangular waveguides.

<Effects of the Invention> As explained above, according to the present invention, the above-mentioned problems can be solved, and the specific advantages are as follows.

(1) Insertion loss is almost negligible (Io, 7+14.
5Gf (0.2 dB or less in the z band).

(2) Uncomplicated structure and light weight.

(3) Simple configuration.

(4) Consistency between control elements 3 (5) Optimal regeneration ability.

(6) Able to operate under wideband and adjacent bands.

[Brief explanation of drawings]

FIG. 1 (al is a structural diagram showing an example of the configuration of a duplexer based on the present invention, FIG. 1 fb) is a view in the direction of arrow A in FIG. 1(a), and FIG. 3 is a block diagram showing the configuration of the circuit for H), FIG. 3 is a diagram for explaining the principle of operation when passing through the band ilI, and FIG. 4 is a diagram for explaining the principle of operation when blocking the band pass. 3... Lateral (rectangular) waveguide 4... Central waveguide 6
...Filtering structure section 10...First 3dB coupler. 11...High-pass filter 12...Second 3dB coupler 16...Cutoff waveguide 17...Filtering section 18
...Coupled waveguide

Claims (2)

[Claims] (1) A splitter for separating high-frequency signals of both waves, which includes a central waveguide (4) that propagates signals of both bands corresponding to the two polarized waves, and a plurality of coupling waveguides. The first waveguide is composed of four lateral waveguides (3) arranged symmetrically with respect to the central four-wave tube (3) connected via a tube (+01), and passes signals of both bands of the same polarization. 3dB coupler θ0)
and 1 connected to the central waveguide and the four lateral waveguides.
pass only signals in one frequency band and are symmetrical with respect to both width wavefronts, and for reflected signals that are in the passband, there are two channels in the central waveguide and one in the lateral waveguide. a filtering section having the same electrical characteristics and having a wave function of band-pass blocking or high-pass type; and a second 3dB coupler (transformer) having the same configuration as the first 3dll coupler θ0). ), which are arranged in cascade. (2) the high-pass type waveguide (6) has a length sufficient to ensure a desired degree of separation by including an extension of the cutoff waveguide for the low frequency band; 2. The duplexer according to claim 1, wherein said extension section has two additional sections αη for high frequency bands disposed in front.