JPS61270904A - Direction finder - Google Patents

Abstract

PURPOSE:To improve the accuracy of direction finding without using any goniometer by turning an Adocock antenna asymmetrically and expanding the aperture of said antenna over one wavelength. CONSTITUTION:n-Set of antennas are arranged on a circle at an equal interval and a center antenna 4, antennas 501, 502-50n on the circle and output transformers 301, 302-30n are provided to form simulatingly n0set of Adocock antennas. The adocock antennas are scanned switchingly and sequentially and turned equivalently to obtain an 8-figure directivity. The directivity is decided by a wavelength lambda of a measured radio wave and the distance (s), and the interval (s) is allowed up to nearly 0.75l practically taking the muffling ratio into consideration. Thus, the interval (s) is expanded to twice, i.e., 1.5l by turning equivalently the antenna in this way, the sectorial error and the polarized wave error are averaged and decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radio direction measuring device that measures the arrival direction of radio waves.

[Conventional technology]

Generally, in a wireless direction measuring device, the aperture of the antenna is made as large as possible to improve measurement accuracy in order to reduce errors caused by elongated objects around the antenna and errors caused by variations in the polarization plane of incoming radio waves.

[Problem that the invention seeks to solve]

In the case of the Adcock antenna, it is impossible to increase the antenna diameter to more than one wavelength even if the antenna elements are multiplexed, and there is a problem in that the purpose of error reduction as described above cannot be achieved.

[Means for solving problems]

The present invention makes it possible to use a goniometer by using an antenna device that can expand the aperture of the Adcock antenna to one wavelength or more by rotating it asymmetrically around one of the conventional Adcock antennas. Therefore, it is possible to provide a high-performance wireless direction measuring device that can improve direction measurement accuracy with a simple configuration.

[Effect]

Figure 1 shows this principle. Antennas 1 and 2 forming an Adcock antenna with a spacing S are provided, and antenna 2 is
When rotated once around antenna 1, transformer 3
It is clear that a figure-8 directional characteristic as shown in FIG. 2 is obtained in the output.

This figure-8 directivity characteristic is determined by the relationship between the wavelength λ of the measurement radio wave and the interval S, but if the silencing ratio is taken into consideration, the interval WIs can be practically allowed up to about 0.75λ. Therefore, by rotating the antenna element 2 as shown in Fig. 1, the spacing S can be doubled, that is, up to 1.5λ, and the peripheral errors and polarization errors are averaged and reduced by this amount, and the degree of the difference is s=0.5λ
It is approximately 1/3.3 compared to the Adcock antenna.

〔Example〕

In reality, as shown in Figure 3, n antennas are arranged at equal intervals on the circumference, with antenna 4 in the center and antenna 50 on the circumference.
1.502...50n and output transformer 301.30
2...3On are provided to form n Adcock antennas in a pseudo manner, and by sequentially switching and scanning the Adcock antennas and equivalently rotating them, a figure-8 directivity characteristic is obtained.

FIG. 4 shows a concrete example of this, in which the output of each Adcock antenna consisting of antenna 4 and each antenna 501, 502...50n is connected to output selector 7 by cable 6. Ru. A switching pulse is synchronously applied to the switching device 6 and the upstream output selector 7 from the switching pulse generator Bti.

Now considering the case where the switching pulse of the antenna 501 is applied, the output of the antenna 4 is changed to the antenna 50 by the switching device 7.
1 and the output from the cable 6 is connected to the output transformer 3 by the selector 8, and the output of the Adcock antenna constituted by the antennas 4 and 501 is obtained at the output j19.

In the next step, the output of the antenna 4 is combined with the antenna 502 by the switching pulse of the antenna 502, and the output of this Adcock antenna is obtained at the output end 9.

The output of antenna 4 is combined by switch 6 with only one antenna at any time.

By sequentially combining the antennas in this manner, the antennas are equivalently rotated, and a step-like figure-8 directivity characteristic corresponding to this rotation is obtained.

FIG. 5 shows an example of this, in which the number of antenna arrays on the circumference is 12.

When determining the sense, if the diameter of the antenna is one wavelength or more, the center antenna 4 cannot be used as a sense antenna. Therefore, for the azimuth component which is the phase difference output of the paired Adcock antenna, the output transformer 3 extracts the phase sum output as a sense component at the same time, and removes the uncertainty of the sense at the rotational position.
Rub.

Since the sum output of the two antennas is nothing but a vector sum of the respective antenna outputs, the difference output (azimuth component) always has a constant phase difference of 90 degrees, so this sum output can be used to determine the sense. As shown in FIG. 4, this sum output is obtained at α in the primary side of the output transformer 3 and is applied to the sense synthesis circuit 10 via the sense switch 12.

The stepped 8-character directional characteristic output and the sense characteristic output shown in Fig. 5 are amplified, then AM detected, and then shaped by a filter and indicated as an image or sense image indicating the direction of arrival.Also, digital display of the direction of arrival is also known by known means. It can be implemented by As with the conventional antenna, a rotation period of about 500 to 1200 revolutions/minute is sufficient.

[Transformation implementation]

If you want to use the antenna of this radio direction measuring device over a wide band and improve its sensitivity and performance, you can use a double array as shown in Figure 6 (however, the number of arrays on the circumference is 8). ), that is, in the low frequency band, there is a central antenna 4 and antennas on the outer circumference (low frequency band antenna system 13).
In the high frequency band, a combination of the antenna 4 and the antenna system on the inner circumference (high frequency band antenna system 14) is used. In this case, since the central antenna 4 is shared by all frequency bands, the antenna heights are all the same, but this is preferable in order to avoid mutual influence between the antennas due to the double arrangement.

〔Effect of the invention〕

The sensitivity of the direction measuring device using the antenna device according to the present invention is basically the same as that of the Adcock antenna, but since no goniometer is used, there is no so-called span error, and there is no goniometer loss, so the sensitivity is improved. In addition, since the spacing between the Adcock antennas, that is, the antenna arrangement aperture can be substantially doubled, highly accurate azimuth measurement can be performed.

The effect of the radio direction measuring device using the antenna device of the present invention is not limited to only the HF band, but also
This can also be applied to the F band.

[Brief explanation of the drawing]

The drawings show examples, FIG. 1 is an explanatory diagram showing the principle of the present invention, and FIG. 2 shows the 8-character directional characteristic obtained by this principle.
! @Figure 3 is a schematic plan view of the antenna arrangement, Figure 4 is a schematic block diagram of the main circuit, Figure 5 is an example of an output signal, and Figure 6 is a schematic diagram of the block configuration of the main circuit.
FIG. 2 is a schematic plan view of a multi-layered antenna. 1... Antenna, 2... Antenna, 3... Output transformer, 4... Center antenna, 501~50n...
Antenna element on the circumference, 6... Cable, 601-6
0n... Antenna on the circumference, 7... Switch, 8...
- Output selector, 9... Output end, 10... Sense synthesis circuit, 11... Switching pulse generator, 12 Sense switch, 13... Low frequency band antenna system, 14...
・Antenna system for high frequency band.

Claims (1)

[Claims] Instead of rotating the Adcock antenna, which is a combination of two vertical antennas at a certain interval, around the center of the interval to obtain a figure-of-eight directional characteristic, as in the past, one vertical antenna is rotated around the central axis. In addition to obtaining the same figure-8 directional characteristics, the rotation doubles the antenna spacing.
A rotating Adcock antenna (hereinafter referred to as an asymmetric rotating Adcock antenna) that can equivalently double the distance between the Adcock antennas, and instead of rotating this antenna, An Adcock antenna system is formed by arranging n vertical antennas at equal intervals on the circumference, combining the central antenna with each antenna on the circumference, and sequentially switching the antennas paired with the central antenna. A feature is that the diameter of the Adcock antenna system can be substantially expanded to twice the distance between the Adcock antennas by performing rotational scanning and extracting the output to obtain a figure-8 directivity characteristic. Direction measuring device.