JPH0260147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna device for azimuth measurement that reduces disturbance errors caused by the installation environment by increasing the diameter of the antenna arrangement circle.

[Conventional technology]

By increasing the diameter of the antenna arrangement circle, it is possible to reduce the influence of re-radiated waves from minute disturbance objects in the installation environment on the direction measurement signal, and to reduce the installation environment error, as shown in the document: 1958 8. Published by Moon Corona Co., Ltd. [Radio Direction Measuring Device] §58.Site Error
This is disclosed in the following sections.

These large-diameter antenna devices include circular switching Doppler phase modulation type antennas,
2. Description of the Related Art Antenna devices such as those of the circulating switching Uhlenweber type and amplitude modulation type are well known.

In addition, the configuration in which the sense determination signal is obtained from the midpoint of the primary side of the transformer connected to the outputs of two antennas or loop antennas is shown in Figure 43 of the above-mentioned document, §18. Unidirectional determination circuit systems. It has been disclosed by et al.

[Problem to be solved by the invention]

In the conventional large-diameter antenna device as described above, the antenna switching connection configuration and direction measurement signal detection configuration, that is, the receiving part and display part, are relatively complex. There is a problem in that there are expectations for an antenna device for azimuth measurement that can be provided at low cost due to its configuration.

[Means to solve the problem]

The present invention selects two antennas at the same time from among a plurality of antennas arranged on a circumference whose diameter is the aperture of the antenna arrangement as described above, sequentially switches and connects them, and outputs each output of the two antennas. The antenna device for direction measurement obtains a direction measurement signal by detecting a phase difference, and also obtains a sense determination signal from the midpoint of the transformer to which each output is connected, and simultaneously selects the above. the distance between the two antennas,
In other words, while setting the antenna spacing to about 3/4 of the wavelength of the highest measurement frequency and forming an antenna pair,
Antenna arrangement means for arranging four or more antenna pairs along the circumference without intersecting each antenna pair;
The above problem can be solved by increasing the diameter of the antenna arrangement by providing a direction measurement signal means for obtaining the above direction measurement signal based on the phase difference signal obtained by connecting to the transformer. It was designed to be solvable.

〔Example〕

Examples will be described below with reference to figures.

FIG. 1 shows the basic configuration of the present invention. As shown in the figure, each output of a pair of antennas 1 and 2 arranged with an interval S on the circumference of the antenna diameter D is The antenna is connected to a transformer 301 provided at the center of the antenna, and has a configuration in which only one pair of antennas having a configuration similar to that of a conventional adkotok antenna with a spacing S are arranged on the circumference of an aperture D.

The secondary output of the transformer 301 has a voltage corresponding to the phase difference between the two antennas, and the midpoint of the primary side of this transformer outputs the sum (phase sum) of the two antennas. are being taken out.

Now suppose that radio waves arrive from the direction shown in Figure 1,
If antennas 1 and 2 are rotated along the circumference with aperture D, the difference output terminal of transformer 301 will have a value proportional to the cos of the angle θ between the center of the two antennas and the direction of arrival of the radio wave. In addition, a phase difference output as shown in FIG. 2 determined by the antenna spacing S (provided that S is negligible compared to the wavelength λ) can be obtained.

This is the same directivity characteristic as when an antenna with a spacing S is rotated around the center of this aperture, and is independent of the size of the aperture of the rotated antenna.

In other words, in general, the aperture D is so small that it can be ignored relative to the distance from the radio wave emission point to the installation point of the antenna device, so antennas 1 and 2 actually have a radius 1/2D of the aperture D. However, this radius is ignored and it is treated as if it were rotating around the center of the aperture D.

Therefore, an azimuth measurement signal similar to the output of a conventional adkotok antenna can be obtained.

In other words, Fig. 3 shows the directivity characteristic sin (πS/λ・cosθ) of the well-known adkotok antenna with the ratio S/λ of the antenna spacing S and the wavelength λ as a parameter. It is clear that the phase difference output when the book antenna is rotated along the circumference also has the same directivity characteristics as shown in FIG. 3.

The phase of this output voltage is determined by the relationship between the direction of the arriving radio wave and the rotation direction of the antenna.
The phase differs by 180 degrees when the directions of arrival are the same and when they are in the opposite direction. This is similar to the fact that the phase of the output of an adkotok antenna differs by 180 degrees depending on whether the direction of arrival is opposite.

There is uncertainty in sensing with only the output obtained by the above configuration, and it is necessary to obtain a signal for sensing determination by some means.

For this reason, it is conceivable to use means for obtaining a sense determination signal from the midpoint of the primary side of the transformer 301, as disclosed in the above-mentioned literature.

In other words, the sum output of two antennas is nothing but the vector sum of their respective antenna outputs, so as shown in Figure 4, the sum output is always equal to the difference output by 90
Since there is a phase difference of approximately
Changed by 90 degrees, same phase as difference output (or opposite phase)
The sense can be determined by synthesizing it as

FIG. 5 shows the phase sum characteristic cos (πS/λ·cos θ) of two antennas with S/λ as a parameter, and S/λ is shown in comparison with FIG. As shown in the figure, when S is small compared to λ, the sum characteristic is almost circular, but as S approaches 0.5λ, it becomes elliptical, and when S = 0.5λ, the output is in the 0 degree and 180 degree directions. It becomes a figure-of-eight characteristic where is zero. When S becomes 0.5λ or more, there is a direction in which S is exactly 0.5λ, so the output becomes zero at this point. Since this direction occurs in each quadrant, the result is a four-lobed output characteristic in which the output becomes zero in a specific direction determined by S/λ (see the characteristics of S=0.75λ and 1λ in the figure). However, as already mentioned, the phase of the sum characteristic is
Regardless of these characteristics or irrespective of the direction of arrival, the signal does not change like the phase of a single vertical antenna, so this can be used to make sense decisions.

Figure 6 shows this sense synthesis characteristic.
This figure shows the case where the characteristics of FIGS. 3 and 5 are used as they are, and the 90-degree phase conversion loss of the sum output is ignored, and they are combined at a ratio of 1:1. When S becomes 0.5λ or more, the sense waveform becomes complicated, but it can be seen that a satisfactory sense waveform can be obtained even when S=0.75λ, which is close to the limit of the antenna spacing according to the present invention.

The above is the principle of the antenna device for direction measurement according to the present invention, but in reality, instead of rotating a pair of antennas, the antennas are arranged on the circumference, and the antenna switcher 401 provided at the center is used to connect the antennas to one pair. The antennas are sequentially switched in a circular manner to obtain the difference and sum outputs.

Figure 7 shows an example in which n antennas are arranged at equal intervals on the circumference (hereinafter referred to as equal interval arrangement), where the antenna element spacing S is determined by the highest measurement frequency, and the antenna aperture D is determined by the antenna Determined by the number of elements n. Now, if S is 0.7λ and the highest measurement frequency is 30MHz, then D is approximately 27m with n = 12 lines.
When n=18, D is approximately 40λ. Also VHF and UHF
In the band, dipole antennas are used, but
In the case of 500MHz, when n=12 lines, D is about 1.6 m, and when n=18 lines, D is about 2.4 m.

Comparing this with that of the conventional circulating switching Doppler type, it is found that in the case of the circulating switching Doppler type, the distance between the switchingly connected antennas, that is, the distance corresponding to the spacing S in the present invention is the maximum.
It is about 0.4 to 0.5.

On the other hand, the spacing S in the present invention is 0.75λ
It can be seen that even if the number of antennas is the same, the diameter D can be made approximately 1.5 times larger in the present invention.

Also, when compared with the conventional adkotoku antenna type, in the case of the adkotoku antenna type, the maximum value of the aperture D can be approximately 3/4λ as mentioned above. , if you look at this on the circumference of the antenna arrangement, it will be an interval of 1/√2, that is, an interval of about 0.53λ.

On the other hand, in the case of the present invention, the spacing S between the antennas on the circumference is set to about 3/4λ, so even if the number of antennas is the same, four antennas are arranged like the adkotok antenna. It can be seen that even in this case, the diameter D can be increased by about 1.4 times in the present invention.

Antenna switching is performed by a switching element provided in the antenna switching device 401. Two antennas are switched at the same time, such as antennas 1 and 2, 2 and 3, 3 and 4, etc., using a switching pulse, and a single output converter is used to output the difference. and output the sum. FIG. 8 shows an example of the signal waveform of the difference output obtained by this switching. If this output is amplified, AM detected, and shaped by a filter, a waveform as shown by the dotted line in the figure can be obtained. The sum output also becomes a step-like wave as shown in FIG. 9, which is shaped by a filter in the same way. Since these waveforms are similar to the output waveforms in the goniometer rotation method, the direction of arrival can be displayed as a propeller image or sense image by modulating the CRT circular sweep signal synchronized with the switching cycle, and the direction can be measured. Digital display of the direction of arrival can also be performed by known means.

When a large number of antennas are arranged as shown in Figure 7, the unused antennas and the used antennas are placed relatively close to each other due to switching connections, so the unused antennas Since re-radiation from antennas and interference between antennas affect direction measurement, there are ways to reduce this effect by grounding or opening the antenna base, or inserting impedance, depending on the direction measurement frequency. , is also used in the conventional system, but it goes without saying that it is necessary to take measures similar to this in the configuration of the present invention as well.

On the other hand, the method of symmetrically arranging m sets of two antennas (hereinafter referred to as the symmetric arrangement method) arranges the antennas in pairs symmetrically on the circumference as shown in Figure 10. Minimum number of antennas in a set is 4
Although it may be a set, it is usually 8 sets or an integral multiple of 8 sets. In the case of this symmetrical arrangement, the spacing S between the antennas in the set is the same as in the case of equally spaced arrangement, but the diameter of the antennas can be arbitrarily selected. For example, when using 8 sets of antennas, the maximum measurement frequency is 30MHz
However, the antenna diameter can be set to 100 m, or even at 500 MHz, the antenna diameter can be set to about 20 m.
Therefore, the characteristics of the large-diameter antenna can be further exhibited, and the influence of other antennas that are not used can also be reduced.

FIG. 10 shows a case where eight sets of antennas are used, and two sets of antennas such as antennas 1 and 2, antennas 3 and 4, and antennas 5 and 6 are switched sequentially at the same time. Although the obtained waveform has a step-like shape as in FIG. 9, it can be processed and measured in the same manner as in the case of evenly spaced antennas, including the sense output.

The present invention is not limited to the two embodiments described above, and various modifications can be made without departing from the gist of the present invention. For example, the seventh
In the figure, in the frequency band where the measurement frequency is low,
The antenna elements 1 and 3, 3 and 5, 5 and 7... or 1 and 3, 2 and 4, 3 and 5... are switched as a set with skipped spacing, and the antenna spacing is doubled. It is also possible to improve the sensitivity and return the combination to antennas 1 and 2 at a frequency where the distance between antennas 1 and 3 is approximately 0.7λ.

〔Effect of the invention〕

According to the present invention, as described above, four or more antenna pairs are arranged by setting the spacing between adjacent antennas arranged along the circumference to be about 3/4 of the wavelength of the highest measurement frequency. However, by sequentially selecting these antenna pairs and switching and connecting them to one transformer, a direction measurement signal similar to that of a conventional adkotok antenna is obtained, so the direction measurement receiving part and display are Although the configuration is as simple as that of a conventional adkotok antenna, the diameter of the antenna arrangement is approximately 1.5 times larger than that of a conventional circulation switching Doppler type, and compared to an adkotok antenna. Since it can be made approximately 1.4 times larger, it can reduce the installation environment error mentioned above, and it eliminates the need for a complicated configuration like the Doppler type, which corrects audio modulation components for FM radio wave measurements. It has the advantage that the entire device can be provided simply and inexpensively.

[Brief explanation of the drawing]

The drawings show embodiments, FIG. 1 is an explanatory diagram showing the principle of the invention, FIG. 2 is a diagram of the phase difference output obtained by this principle, and FIG. 3 is the characteristic of the phase difference output of two antennas. In other words, Figure 4 shows the directivity characteristics of the Adkotoku antenna, Figure 4 is a vector diagram showing the phase difference and sum of the two antennas, Figure 5 is the phase sum characteristic diagram of the two antennas, and Figure 6 is the vector diagram showing the phase difference and sum of the two antennas. The difference between FIG. 3 and FIG. 5 and the combination (sense) characteristics of the sum output are shown by each S/λ. FIG. FIG. 8 is a difference output diagram obtained by switching the equally spaced antennas shown in FIG. 7, and FIG. 9 is a sum output diagram of the antennas. Further, FIG. 10 is a schematic diagram of the configuration of a symmetrical arrangement method of another embodiment. 1 to 16, n...Antenna, 301...Transformer, 401...Antenna switcher, 501...Antenna element, 601...Antenna connection cable.

Claims (1)

[Scope of Claims] 1. Two antennas are selected at the same time from among a plurality of antennas arranged on a circumference having a diameter equal to the diameter of the antenna arrangement, and the outputs of each of the two antennas are sequentially switched and connected. An antenna device for direction measurement, which obtains a direction measurement signal by detecting a phase difference, and also obtains a sense determination signal from the midpoint of a transformer to which each of the outputs is connected, wherein a. The spacing between the two antennas (hereinafter referred to as antenna spacing) is set to about 3/4 of the wavelength of the highest measurement frequency to form an antenna pair, and four or more of the antenna pairs are arranged without intersecting each antenna pair. (a) antenna arrangement means disposed along the circumference; (b) determining the orientation based on the phase difference signal obtained by connecting each output of each antenna pair in each of the switching connections to one transformer; An antenna device comprising: azimuth measurement signal means for obtaining a measurement signal. 2. The antenna device according to claim 1, characterized in that: (a) an interval is provided between each pair of the antenna pairs that is larger than the antenna interval and does not perform the selection; The antenna arranging means is provided with the antenna arranging means. 3. The antenna device according to claim 1, further comprising: (a) the antenna arrangement means in which one antenna of each of the antenna pairs is arranged in common with one antenna of the antenna pair that is next in the switching connection order; What to have. 4. Selecting two antennas at the same time from among a plurality of antennas arranged on a circumference whose diameter is the aperture of the antenna arrangement, sequentially switching and connecting them, and detecting the phase difference between the outputs of the two antennas. In an antenna device for measuring a direction, which obtains a signal for direction measurement from the midpoint of the transformer to which each of the outputs is connected, and obtains a signal for sense determination from the midpoint of the transformer to which each of the outputs is connected, the antenna device performs direction measurement over a wide band of frequencies, a) a steady spacing arrangement means for setting the spacing between the two antennas (hereinafter referred to as steady antenna spacing) to approximately 3/4 of the wavelength of the highest measurement frequency and arranging them on the circumference; b. A frequency at which the interval between two antennas selected by appropriately skipping the arranged antennas (hereinafter referred to as skipped interval) is approximately 3/4 of the wavelength of the frequency in the middle of the wide band (hereinafter referred to as in-band intermediate frequency) c. For direction measurement at a frequency higher than the in-band intermediate frequency, two antennas with the constant spacing (hereinafter referred to as a pair of constant spacing antennas) are selected and the switching connection is performed. For direction measurement at a frequency lower than the intermediate frequency within the band,
switching connection selection means for selecting two antennas based on the staggered spacing (hereinafter referred to as staggered spacing antenna pairs) and performing the switching connection; an antenna arranging means arranged along the circumference without causing any interference; an azimuth measurement signal means for obtaining the azimuth measurement signal based on the phase difference signal obtained by being connected to an antenna device. 5. The antenna device according to claim 4, wherein: (a) one antenna of each pair of regularly spaced antennas is arranged in common with one antenna of the pair of regularly spaced antennas that is next in the order of the switching connection. Or, the antenna arrangement means is arranged such that one antenna of each of the interlaced interval antenna pairs is arranged in common with one of the antennas of the interlaced interval antenna pair that is next in the switching connection order.