JPS58127413A - Tracking signal detector - Google Patents

Abstract

PURPOSE:To detect a tracking signal only without making large-sized device and without affecting on a communication signal, by providing plural probes having their length toward the axial direction around the internal circumference of a circular taper waveguide forming a feeding path. CONSTITUTION:The probe 2 having about 1/4 wavelength of the operating frequency is provided at four positions at the circumference of a horn antenna axially, at the inside of the taper waveguid 1 of the circular horn antenna for circular polarized wave communication receiving the basic mode TE<0>11 wave and at a diameter being the transmission region to a TM<0>01 wave used for the tracking, and a detection element led externally with a coaxial line is provided at the root of the probes 2. A diameter D of the feeding waveguide is set so that the basic mode TE<0>11 wave used for communication is propagated and the TM<0>01 mode wave is cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tracking signal detector used for self-tracking the arrival direction of all radio waves from an antenna in a circularly polarized communication system.

Conventionally, in order to equip an antenna with a self-tracking function, when the antenna's pointing direction deviates from the communication target, a high-order mode of TM, 1 wave, induced in the antenna is detected, and this is used as a self-tracking function. A method has been adopted in which the error signal is used as an error signal. This method can be roughly divided into two types:
There are different methods. That is, after detecting the basic mode TE wave used for 9 communication and the TMo wave for self-tracking using a dedicated coupling device without distinguishing between them.

The first method is to separate the TMo mode and the TEl mode by using the difference in phase relationship caused by the difference in the electromagnetic field distribution between the two modes, and the first method is to separate the TMo mode and the TEl mode by using the difference in the phase relationship caused by the difference in the electromagnetic field distribution. There was a second method of using a coupling device for detection.

However, all of these conventional methods are TMo.

In order to extract the waves to the outside, a dedicated mode coupling device with special functions is required, making it large and
Each had the following drawbacks. That is, in the first method, TM. Since not only the , wave but also the TE,', wave is detected once, if the frequency used for tracking and the frequency used for communication are the same, the 9 communication signal TE,
, the wave, the tracking signal TMo, and the signal pass through a separation circuit for separating the numbers, resulting in deterioration of communication signal characteristics such as increased insertion loss. In addition, when the frequency used for tracking and the frequency used for communication are the same, the second method attempts to detect only the tracking signal TMo, without affecting the communication signal TE, wave as much as possible. As a method, there is a method of separating the TE mode and the TMo1 mode using a distributed coupling line by utilizing the difference in phase constant in the transmission waveguide.

However, this second method has the disadvantage that the coupler constituting the distributed coupling line becomes large and expensive, and there are significant restrictions on its use.

FIG. 1 is a transparent perspective view showing a conventional detection device to which the first method is applied. This detection device cannot detect both TEI, waves, TMo, and waves.

Tracking signal TMo, wave frequency (f2) is communication signal T
If the wave frequency (f,) is different from the wave frequency (f,), a filter is installed in each of the detection waveguides a and b in Fig. 9, and the communication signal T is
It is necessary to prevent the wave (f+) from being influenced by the tracking signal detector. If the image frequencies are the same, the communication signal must be detected from the reverse phase synthesis terminal of the hybrid synthesis circuit of the detection device, which is not practical. Further, FIG. 2 is a cross-sectional view showing a conventional detection device to which the above second method is applied. According to this example, 9 communication basic modes T
E., to avoid affecting the waves.

Only the high-order mode TMo for tracking and waves are detected using a distributed coupling line.

The object of the invention is to solve one or more disadvantages, to be inexpensive and to
As well as making downsizing possible.

The object of the present invention is to provide a complete tracking signal detector that can detect only the TMo1 wave, which is a necessary tracking signal, and the TE wave, which is a communication signal, with almost no influence on the wave.

According to the present invention, in order to cause a circularly polarized communication antenna that receives waves to self-track in the direction of arrival of radio waves, a fundamental mode TE is provided in a power feed path including the antenna, and from a reception input to a higher order mode. TMe.

In a tracking signal detector for detecting waves, a plurality of probes having a length in the axial direction of the waveguide are all arranged around the inside of a circular tapered waveguide forming the power feeding path, and A tracking signal detector is obtained, which is characterized in that only the higher-order mode 1-lock wave is detected by these probes.

The present invention will be described in detail below with reference to the drawings.

FIG. 6 is a front view and a side sectional view showing an embodiment in which the present invention is applied to a conical horn antenna. In the figure, 1 is a tapered portion and 2 is a probe. For the TMo 1 wave used for tracking in a normal conical horn antenna, the diameter portion in the transmission range = approximately 1/4 wavelength of the operating frequency probe 2 (length t) is placed at four locations around the horn antenna. Each of these probes is provided in the axial direction, and furthermore, a detection element is provided at the root portion of each of these probes and guided to the outside by a coaxial line. In this case, the circular feeding waveguide (diameter D) connected to the horn antenna can propagate only the basic mode TEτ1 wave used for communication, and is in the cutoff region for TMo and modes. is set to be. and,
The size of the insertion point of the probe is selected at a position where the TMo1 mode wave is detected most efficiently. Also, consideration should be given to making one dimension d as short as possible. On the other hand, θ is the fundamental mode TE,
TM is preferably 0 so that the first wave component is not detected by the probe 2. , in order to detect more waves, the horn should be parallel to the axis of the antenna.

When the direction of the incoming radio wave deviates from the axis of the horn antenna with this type of structure,

Fundamental mode TE, waves and higher order modes TM. , waves are received. Both mode waves are normally modified mode waves of the TE mode and TMo mode in the circular waveguide in a 9-conical horn, but the TE mode has very little electric field component in the axial direction of the antenna. .

The TMo1 mode has an axial electric field component that is almost the same as in a normal circular waveguide. Therefore, the probe 2 is excited only by the TMo wave and is hardly excited by the TE11 wave. The TE11 wave is then transmitted as it is to the circular waveguide at the subsequent stage.

FIG. 4 is a block diagram showing the overall configuration of a tracking signal detector adapted to the embodiment of FIG. 5. In this figure, the TMo waves excited by the four probes 2 are taken out to the outside through a coaxial line and guided to a two-combining circuit. That is, the probes 2-1 and 2-6 and 2-2 and 2 are opposed to each other.
-4 output ends all 180 phase type hybrid 6 and 4
Connect to the in-phase terminals of each. Furthermore, when the in-phase synthesis terminals of the no-ibrid 6.4 are connected to another hybrid 5 while maintaining the in-phase relationship, the in-phase synthesis output terminal of the no-ibrid 5 receives TM induced in the horn antenna. , the power due to waves only is detected.

Although a small amount of TEτ1 wave is actually induced in the probe 2 of the horn antenna, this amount is negligible as a reduction in the level of the communication signal, and it is negligible when synthesized by the hybrid 6.4 of the synthesis circuit. Reflection terminators 6 and 7 were connected. Since the signal is guided to the reverse phase synthesis terminal, deterioration in tracking performance is not a practical problem.

With such a function, it is possible to separate and detect only the TMo wave that occurs when the direction of the antenna deviates from the target. But of the antenna.

A reference signal is required for self-tracking.

This signal has the same basic mode TE as the 9 communication signal.

waves can be used and the output signal of a circular to linear polarization converter connected behind the horn antenna can be used.

In the above embodiment, the probe is inserted into the tapered part of the conical horn antenna.

Even when there is a cutoff point for TM waves in the middle of a part of the tapered waveguide of the feed line connected to the rear stage of the antenna, the tracking signal detector of the present invention can be provided with exactly the same configuration. Needless to say, it can be done.

As is clear from the above explanation, according to the present invention, in a bicircularly polarized wave communication system, simply by fully inserting a probe having a length in the axial direction into the tapered part of the circular waveguide forming the power feeding path. Small and small.

The advantage of this method is that it can be equipped with an economical tracking signal detector and contributes to the simplification of the system.

[Brief explanation of the drawing]

FIG. 1 is a transparent perspective view showing the structure of a conventional detection device that detects the fundamental mode TE, 1 wave and the higher order Mo, 1 wave, and then separates them to obtain the TMo, wave. Figure 2 is a side sectional view showing the structure of a conventional detection device that detects only the tracking signal TM wave using a mode coupler using a distributed coupling line, and Figure 3 shows the structure of a conventional detection device when the present invention is applied to a conical horn antenna. A front view and a side sectional view showing the structure of one embodiment, and FIG. 4 is a block diagram of a synthesis circuit for synthesizing the 1M61 wave detected by the probe of FIG. 6. Explanation of symbols: 1 is the tapered part of the conical horn antenna, 2 is TM:, a probe for detecting waves, 3,4゜5 is the in-phase/reverse-phase combination type no hybrid, 6.7 is the non-reflection termination Each vessel is covered with rain. /T's "0°2 T bow, shi εL (chi 2) Figure 1 Introduction Figure 3 'l Figure 4

Claims (1)

[Claims] 1.In order to make the antenna for circularly polarized communication that receives fundamental mode TE, 1 wave self-track in the arrival direction of the radio wave, it is installed in the feed line including the antenna, and receives the higher-order mode TE, 1 wave from the reception input. In a tracking signal detector for detecting a signal, a plurality of probes having a length in the axial direction of the waveguide are all arranged around the inside of the circular tapered waveguide forming the power supply path, and a plurality of probes having a length in the axial direction of the waveguide A tracking signal detector characterized in that only the next mode 1 lock o1 wave is detected by these probes.