JPH03267803A - Antenna changeover feeding system - Google Patents

Abstract

PURPOSE:To eliminate distortion of a radiation pattern and to reduce production of an undesired wave by connecting a dummy load having an impedance equivalent to an output impedance of a transmitter for each antenna at the terminal of a changeover feeding circuit and terminating each antenna at nonconduction with the dummy load. CONSTITUTION:A dummy load having an impedance equivalent to an output impedance of a transmitter is connected for each antenna to an antenna terminal of a changeover feeding circuit to select plural antennas sequentially to be opened and each antenna at non-conductive state is terminated by the bummy load, in the antenna changeover feeding system for a doppler VOR side band antenna especially which is useful for the antenna changeover feeding system selecting plural antennas sequentially to be opened and closed, and each antenna in the open state is terminated by the dummy load. Thus, production of an undesired wave or distortion in the radiation pattern due to a change in the impedance at the closing and opening of the antenna is eliminated and the adjustment of a cable in the side wave band antenna is avoided.

Description

[Detailed Description of the Invention] E-Industrial Application Field] The present invention relates to an antenna switching power feeding system that switches and feeds signals from a transmitter to a plurality of antennas, and is particularly applicable to switching power feeding of sideband antennas of a Doppler VOR. The present invention relates to a useful antenna switching feeding system, and more particularly to generation of a switching waveform that is optimal as a switching waveform for a sideband antenna of a Doppler VOR.

[Prior Art] Generally, when a radiation pattern is formed by switching and feeding a plurality of adjacent antennas and used for communication, or to provide azimuth, distance information, course setting, etc. Transmission power from the transmitter is sequentially switched and fed to each antenna using the antenna switching waveform, but the transmitter is connected to the antenna when it is conducting, and the other antennas are open when it is not conducting. The situation is as follows.

The current Doppler VOR has a carrier wave antenna that is omnidirectional in the horizontal plane and a sideband antenna, and a 30 Hz amplitude modulated wave is radiated from the carrier wave antenna as a reference phase signal.

On the other hand, the sideband antenna radiates the sideband signal while rotating on the circumference of the radius r in synchronization with this 30H2, but it is mechanically smoothed by the switching feeding system using a distributor. This forms an antenna array equivalent to an antenna that rotates around the antenna.

Therefore, in the switching power feeding system of the sideband antenna of the current Doppler VOR, a half-wave sine waveform is used as the switching waveform, as shown in Figure 6, due to the simplicity of the device configuration and manufacturing reasons. , 50 sideband antennas A, , A2 . A3
. . . are sequentially switched and fed to obtain an equivalent rotationally moving antenna.

Here, if the sideband signal is being fed to the sideband antenna A, then the sideband antenna A is connected to the sideband transmitter (
) are connected and in a conductive state, and the other sideband antennas A2. A, . . . are in an open state.

On the other hand, as shown in FIG. 8, the switching waveforms of the sideband antennas A+, A2, A3, etc. are infinitely continuous on the left and right sides of the main lobe M.
The inventors have analyzed that the ideal sinX/X waveform W forming SRI, SR2, etc. is optimal.

However, as a practical matter, this ideal sinX
/X waveform W is difficult to form with current technology. That is, since the sinX/X waveform W has no periodicity, it is impossible to realize a distributor having such a switching waveform.

Therefore, as shown in FIG. 9, the inventors first synthesized waveforms in which the envelope was approximated by a sine waveform, and approximated the ideal sinX/X switching waveform W (indicated by a dotted line). An apparatus for obtaining a sinX/X sine wave approximation waveform W' (indicated by a solid line) was prototyped.

The dotted line shows the ideal sinX/X switching waveform W.
sinX/X compared to the sine wave approximation waveform W'',
The /X switching waveform W is a waveform tilted toward the center 0 direction.

[Problems to be solved by the invention] Since the transmitter is connected to the antenna when it is conducting, the impedance seen from the antenna side is the output impedance of the transmitter, whereas the antenna when it is not conducting is Since it is in an open state, the impedance becomes infinite, and the change in impedance between when the antenna is conducting and when it is not conducting is large, which distorts the radiation pattern and causes the generation of unnecessary waves.

On the other hand, in the case of a Doppler VOR, when the sideband signal is not being fed and is non-conducting, the impedance becomes extremely large at the end of the distributor on the sideband antenna side. Therefore, in order to minimize mutual coupling with adjacent sideband antennas and the centrally located carrier antenna, the distributor is designed so that the impedance seen from the sideband antenna side is very large when it is not conducting. The length (electrical length) of the power supply cable from At the same time, skilled techniques were required.

Furthermore, even if the cable is properly adjusted, the impedance changes between when the sideband antenna is conducting and when it is not conducting are large, so the radiation pattern of the carrier antenna is distorted due to re-radiation, unnecessary wave radiation, and the direction This was causing an error.

Furthermore, when using a half-wave sine waveform that approximates a staircase shape as shown in FIG. Therefore, there is a problem in that a high-order switching frequency spectrum due to quantization noise is generated as an unnecessary signal. In addition, the switching waveform distorts the received signal, causing azimuth errors.

Moreover, the sinX/X sine wave approximation waveform W' with the envelope shown by the solid line in FIG. 9 is used as the switching waveform of the sideband antenna because the ideal sinX/ This is different from the X waveform W. Therefore,
This difference between the two waveforms also caused distortion of the received signal.

[Means for Solving the Problems] The present invention provides a pseudo load equivalent to the output impedance of the transmitter for each antenna at the antenna side end of a switching feed circuit for sequentially switching a plurality of antennas into conduction and non-conduction. At the same time, each antenna is terminated with a pseudo load when it is not conducting, thereby eliminating distortion of the radiation pattern and generation of unnecessary waves due to changes in impedance between when the antenna is conducting and when it is not conducting. .

In addition, in the case of a Doppler VOR using a distributor that switches and feeds the sideband signal to the sideband antenna, a pseudo load equivalent to the output impedance of the sideband transmitter is placed on each end of the distributor on the sideband antenna side. In addition to connecting each waveband antenna to each waveband antenna, when the sideband antenna is not conducting, connect the sideband antenna side end of the distributor to
By inputting a control signal for switching to a dummy load, when the sideband antenna is conducting, the sideband transmitter is connected to the end of the sideband antenna side of the distributor, and when it is not conducting, it is terminated at the dummy load. This eliminates cable adjustment work, as well as unnecessary wave radiation and azimuth errors.

Furthermore, a pseudo sinX/X switching waveform w" having a periodic envelope approximated by the envelope of the ideal sinX/X waveform W is synthesized as the switching waveform of the distributor, thereby removing distortion of the received signal. It is something.

[Operation] First, the main lobe and side lobes of the ideal sin Lobes and sidelobes are temporally synthesized to generate periodic pseudo sinX/
The X switching waveform W'' is synthesized, and this pseudo sinX/X switching waveform W'' is input to the distributor of the Doppler VOR.

On the other hand, a pseudo load equivalent to the output impedance of the sideband transmitter is connected to the sideband antenna side end of the Doppler VOR, and when the sideband antenna is not conducting, the sideband antenna side end of the distributor is connected. By inputting a control signal to switch to a dummy load, when the sideband antenna is conducting, a sideband transmitter is connected to the end of the sideband antenna of the distributor, and when it is not conducting, it is terminated at the dummy load. Therefore, changes in impedance seen from the sideband antenna side when the sideband antenna is conducting and non-conducting are eliminated.

[Embodiment] FIGS. 1 to 5 show embodiments of the present invention, and a case where the invention is applied to a DSB type Doppler VOR using a distributor as a switching power supply circuit will be described.

FIGS. 1(a) to (c) and FIG. 2 show pseudo sinX/
This shows a block diagram of the main parts of the device that generates the X-switching waveform W'', and Figure 1 (a) shows the sideband transmitter (waveform generator).
1, the ideal sinX shown in FIG.
A waveform having an envelope of /X waveform W is formed, respectively.

FIG. 1(b) shows a basic configuration diagram of the waveform synthesizer 2, in which a main lobe and a desired number of side lobes are temporally synthesized to generate a periodic waveform having an envelope of an ideal sinX/X waveform W. A pseudo sinX/X switching waveform W'' is generated.

FIG. 1 (C) shows a basic configuration diagram of the distributor 3, and FIG. 2 shows a schematic block diagram of FIG. 1.

Hereinafter, the configuration diagram of the lower sideband section is the same as the configuration diagram of the upper sideband section, so the configuration of the lower sideband section is omitted.

Here, as shown in FIG. 8, the ideal sin SL2, Sn3..., SR1, SR
In this embodiment, as shown in FIG. 3, a main lobe M and 4 (1 side lobes SLI
, Sn2, Sn3, Sn4, SR1, SR2, SR3,
A pseudo sin X /

This pseudo sinX/X! , l] The main lobe M, side lobes SLI to SL4, and envelopes from side lobes SRI to SR4 of the detected waveform W" are ideal as shown in FIG. 8 (indicated by the dotted line W in FIG. 9). si
It is the same as nX/X waveform W.

A,, A2 φ... indicates the number of the sideband antenna.

FIG. 2 shows a schematic block diagram, where l is the waveform generator (corresponding to the sideband transmitter) shown in FIG. Wave band transmitting unit l
l, 4-way divider 12 and sideband transmitting unit) 13-16
As shown in Figure 3,
The main lobe M1. from the sideband signals respectively. M2 and main lobe M1. Waveforms of side lobes 5R1SL located on the right and left sides of M2 are independently obtained.

Reference numeral 17 indicates a lower sideband section, which has the same circuit configuration as the upper sideband section.

2 is a waveform synthesizer shown in FIG. 1(b), and side lobe SL1. SL2. SL3, Sn4 and SRI
, SR2, SR3, and SR4 phase shifter 18
, an attenuator 19 for adjusting amplitude, and a diode switching circuit 20, and the main lobe M1. A pseudo sinX/X switching waveform W'' is synthesized from the CW waveforms of M2 and sidelobes SR and SL.

The diode switching circuit 20 is controlled by a control signal from the logic circuit 4 (a timing chart is shown in FIG. 4), and the main lobe M1. This is to temporally synthesize M2, sidelobes SLI to SL4, and 5RI-3R4 to synthesize a periodic pseudo 3inX/X switching waveform W''.

21 is a lower sideband section, which has the same circuit configuration as the upper sideband section.

3 is a distributor shown in FIG. 1(C), and 22
23 is a diode switching circuit used in conventional distributors, and 23 is a pseudo load circuit.
It is composed of a switch section 24 controlled by a control signal input to a control signal input terminal P, and a pseudo load 25 having an impedance equal to the output impedance of the sideband transmitter, and 50 sideband antennas A. ,,A2os
are connected to each other.

A control signal for the distributor (a timing chart is shown in FIG. 5) is input to the control signal input terminal P, and the sideband antenna A1. A2... is connected to a sideband transmitter, and when non-conducting, a pseudo load 25
is controlled so that it is connected.

Therefore, the sideband antennas A, , A when conducting and when not conducting.
2. It is constructed so that there is no change in impedance when viewed from the back side.

Note that the pseudo sinX/X switching waveform W in this example
”Then, the side lobes SLI, SL2,..., SRI,
Since four SR2 and - are used each, the sideband antennas A, A2 and ΦΦ are in a conductive state with two main lobes and eight side lobes, making a total of 10 antennas. There is.

Therefore, the pulse of the distributor control signal shown in FIG. 5 has a pulse width corresponding to the time of ten sideband antennas. That is, sideband antenna A
1. A2... are 50 antennas, so one sideband antenna A1. A2... is 7.2°, and the pulse width is 72'''.

4 is a logic circuit based on the oscillation frequency of the crystal oscillator 5, which includes a waveform generator 1, a waveform synthesizer 2, and a distributor 3.
In order to synchronize the two with each other, control signals shown in FIGS. 4 and 5 are generated.

6 is a reference signal generator of the carrier wave transmitter.

Next, the operation will be explained.

First, the case of synthesizing the pseudo sinX/X switching waveform W'' shown in FIG. 3 will be described in detail based on FIGS. 1 and 2.

In the waveform generator 1, as shown in the block diagram of the main part in FIG.
The carrier wave signal of the OR is divided into two parts by a two-way divider lO, and inputted to the upper sideband oscillation unit 11 and the lower sideband section 17, respectively.
960Hz higher upper sideband signal and carrier signal than 99
A 60Hz lower lower sideband signal is generated.

Here, since the upper sideband signal section and the lower sideband signal section have the same circuit configuration, only the upper sideband signal section will be described below.

The upper sideband signal is divided into four parts by a 4-way divider 12, and input to sideband transmitting units 13 to 16, respectively, and sinX/X
After being directly modulated by the main lobe and side lobe waveforms of the waveform W and power amplified, the main lobe M
1, M2 and side lobes SR, S located to the right and left of the main lobes M1, M2, respectively.
L CW waves are formed separately.

At this time, the side lobe SR is changed to the main lobe M1 or M
If the signal is located on the right side of 2, the side lobe S
L is a waveform located on the left side of the main lobe Ml or M2 and tilted toward the center of each other, and has a periodic envelope approximated by the envelope of the ideal sinX/X waveform W shown by the dotted line in Fig. 9. is formed.

Each main lobe M1. from waveform generator l. M2
The sidelobe SR and SL signals are input to a waveform synthesizer 2 shown in FIG. 1(b).

As is clear from FIG. 3, the main lobe M1 and the main lobe M2 are shifted by a half period, so they are taken out one by one in the diode switching circuit 20.

On the other hand, in this embodiment, as shown in FIG.
The side lobe of the pseudo sinX/X switching waveform is the main lobe M1. Since four lobes are generated on each side of M2, the main lobe M1. The sight lobes SR and SL located on the right and left sides of M2 are each divided into four.

Here, each side lobe 5LI-3L4 and 5RI-
Since the phase of the upper sideband of 3R4 is different from the main lobe, the four divided left and right sidelobes are phase-adjusted by the phase shifter 18, and then As shown in (indicated by dotted lines in the figure), after the amplitudes of the main lobes M1 and M2 are set to a predetermined amplitude with respect to the amplitudes of the main lobes M1 and M2, respectively, the attenuator 19 sets the amplitude. It is input to the diode switching circuit 20 at the same time as M2.

On the other hand, based on the oscillation frequency from the crystal oscillator 5, a control signal obtained by the logic circuit 4 (a timing chart is shown in FIG.
0, and this control signal opens the gate of the diode switching circuit 20, and the main lobe M1
．． M2 and sidelobes SLI~SI, 4 and SR
As shown in FIG. 3, I to SR4 are temporally synthesized to form a periodic pseudo sinX/X switching waveform W'', which is input to the distributor 3.

The pseudo s shown in FIG. 3 synthesized by the waveform synthesizer 2
The inX/X switching waveform W″ is generated from the output terminals IX, 2x, etc. to the distributor 3 shown in FIG.
is input to the input terminals IY, 2Y, etc., and the 10 sideband antennas AAz ・Φ・ form a set and are in a conductive state.
50 sideband antennas A rotating while shifting one by one
, , A2 @... are sequentially switched and supplied with power.

Since the Do2Pler VOR in this embodiment is of the DSB type, there are ten sideband antennas A, which are diagonally diagonal to each other.
, A2 . . . are simultaneously turned on and rotating.

On the other hand, since the control signal for the distributor shown in FIG. 5 is input to the control signal input terminal P, the diode D of the diode switching circuit 22 is turned off when the control signal for the distributor is at a high level. Since the switch section 24 of the pseudo load circuit 23 is turned on, the sideband antenna A1 . connected to the diode D is turned on. A2
... is disconnected from the sideband transmitter side and becomes non-conductive, and the sideband antenna A
, are connected to the pseudo load 25.

At this time, when the sideband antenna A is in a conductive state, the impedance seen from the antenna side becomes the output impedance of the sideband transmitter, and when the sideband antenna A is in a non-conductive state, the impedance is equal to the impedance of the pseudo load 25, so Changes in impedance between conduction and non-conduction are eliminated.

In this embodiment, since the Doppler VOR adopts the DSB method, a total of 20 sideband antennas A, A2, . There will be.

In this way, the ten sideband antennas AA2... rotate as a set and shift one by one according to the timing chart shown in FIG.

Note that this invention is not limited to the above embodiments,
In general, the same effects can be obtained when switching and feeding a plurality of adjacent antennas.

Also, in this example, up to four sidelobes SLI to SL4 and SRI to SR4 are synthesized, but if more sidelobe waveforms are formed and synthesized, an even more ideal sinX/X switching waveform can be obtained. can be approached.

[Effects of the Invention] The present invention connects a pseudo load equivalent to the output impedance of a transmitter to the antenna side end of a switching feed circuit for sequentially switching a plurality of antennas into conduction and non-conduction for each antenna, and Since each antenna is terminated with a pseudo load when it is not conducting, it is possible to eliminate distortion in the radiation pattern.

Generation of unnecessary waves can be reduced.

In addition, a pseudo load equivalent to the output impedance of the sideband transmitter is placed at the end of the sideband antenna side of the distributor that switches and feeds the sideband signal to the sideband antenna of the Do7pler VOR. By connecting each antenna separately and inputting a control signal to switch the sideband antenna side end of the distributor to a pseudo load when the sideband antenna is non-conducting, the sideband antenna side end of the distributor can be connected to When the sideband antenna is conducting, the sideband transmitter is connected, and when it is not conducting, it is terminated with a pseudo load. Therefore, the change in impedance of the sideband antenna due to the switched feeding of the sideband signal is suppressed. Since this can be suppressed, distortion of the radiation pattern is reduced, and azimuth errors and unnecessary waves can be reduced.

Furthermore, since the sideband antenna is always connected to the sideband transmitter or dummy load, the impedance change seen from the sideband antenna side is small, eliminating the need for the traditional precision adjustment of the feed cable. No longer needed.

In addition, the main lobe and side lobe of the sin A periodic pseudo sinX/X switching waveform is synthesized by adjusting the amplitudes and temporally synthesizing them, and inputs this pseudo sinX/X switching waveform to the distributor of the Doppler VOR to switch and feed the sideband antenna. Therefore, azimuth errors and unnecessary wave radiation can be reduced.

[Brief explanation of drawings]

1 to 5 show embodiments of the present invention, and FIGS. 1(a) to 5(C) and 2 show pseudo-si
Figure 1 (a) is a block diagram of the main parts of the device that generates the nX/X switching waveform W'', and Fig. 1 (b) is the block diagram of the main parts of the sideband transmitter. Basic configuration diagram, Figure 1 (, c) is a basic configuration diagram of the distributor section, Figure 2 is a schematic block diagram of Figure 1, Figure 3 is a pseudo sin
FIG. 4 is a timing chart of the control signal of the waveform synthesizer, and FIG. 5 is a timing chart of the control signal of the distributor. Figures 6 and 7 show conventional examples. Figure 6 is a switching waveform diagram of a conventional Doppler VOR, Figure 7 is a basic configuration diagram of a distributor of a conventional Doppler VOR, and Figure 8 is an ideal diagram. The sinX/X waveform diagram in FIG. 9 shows the conventional switching waveform diagram and the ideal switching waveform diagram shown in FIG. l...Sideband transmitter (waveform generator) 2...Waveform synthesizer 3φ/9 distributor 25 fist...Pseudo load Ml, M2-fist/main lobe 5l-54...No. side lobe W ...Ideal sinX/X waveform W"...Pseudo 5 i IX/X switching waveform A2...φ
sideband antenna

Claims (3)

[Claims] (1) In an antenna switching feeding system that sequentially switches and feeds signals from a transmitter to multiple antennas to form a radiation pattern, the antenna side of a switching feeding circuit that sequentially switches the plurality of antennas into conduction and non-conduction. An antenna switching power feeding system characterized in that a pseudo load equivalent to the output impedance of the transmitter is connected to each of the antennas, and each antenna when non-conducting is terminated with the pseudo load. (2) A pseudo load equivalent to the output impedance of the sideband transmitter is placed on the sideband antenna side end of the distributor that switches and feeds the sideband signal to the sideband antenna of the Doppler VOR for each sideband antenna. By connecting each antenna to each antenna and inputting a control signal for switching the side end of the side band antenna of the distributor to the pseudo load when the side band antenna is non-conducting, the side wave of the distributor can be connected to each antenna. 2. The antenna switching feeding system according to claim 1, wherein the band antenna side end is connected to the sideband transmitter when the sideband antenna is conductive, and is terminated at the pseudo load when the sideband antenna is not conductive. . (3) The main lobe and side lobes of the sinX/X waveform are formed separately, and the main lobe and a desired number of side lobes are By adjusting the phase and amplitude and temporally synthesizing them, a periodic pseudo sinX/X switching waveform is synthesized, and this pseudo sinX/X switching waveform is converted into a Doppler VO.
3. The antenna switching power feeding system according to claim 2, wherein the antenna switching power feeding system is characterized in that the sideband antenna is switched and fed by inputting the signal to the R distributor.