JP2003262666A - Tracking antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tracking antenna apparatus which is hard to be interfered by a radio wave barrier, such as power transmission lines when mounted to a mobile and used and can surely and stably acquire the direction of a arrival radio waves, since an antenna determines the direction of the arrival radio waves by itself and returns the direction to a tracking apparatus. <P>SOLUTION: In the tracking antenna apparatus, n directional sub antenna elements are fixed around a directional main antenna element so as to constitute n-divided globe detection system and a tracking drive apparatus integrally changes directions of all the antenna elements. The tracking antenna apparatus is provided with a reception means for generating n-detected outputs by independently heterodyne-detecting each high-frequency received signal, obtained from the n sub antenna elements of the n-divided globe detection system, a detection means for detecting the maximum received signal power direction by a comparison operation process, based on the n-detected outputs from the reception means and a control means for feedback-controlling the tracking drive apparatus so as to direct the main antenna element to the maximum power direction, based on a detected result from the detection means. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking antenna device for tracking an antenna in a radio wave arrival direction in a mobile station such as a vehicle-mounted station. Also,
The present invention is based on the "advanced satellite
It is based on the findings found in the research process of "Research and Development for Applying Communication Technology to Medicine".

[0002]

2. Description of the Related Art In a directional microwave antenna, when the directional antenna is tracked in the direction of the transmission source of the radio wave to be captured, if the transmission source is previously recognized, its position information Based on the above, the direction of the antenna is moved from the tracking position to the transmission source by the tracking device.
In this case, when the transmission source is moving, the computer always calculates the direction that changes with the movement based on the movement data, and the tracking device is controlled by this calculation result to change the pointing direction of the antenna. There is.

As a tracking antenna device to be mounted on a moving body such as a vehicle, for example, a BS receiving antenna or the like which determines the strong direction of a radio wave by itself to perform tracking has been put into practical use. An open loop system is adopted in which the direction of the directional antenna is arbitrarily swung to orient the antenna in the direction of the strongest radio wave, and the tracking response is not sufficiently satisfactory.

On the other hand, in microwave communication, it is already known that the antenna is equipped with a dedicated tracking power feeding system for making the antenna face the incoming radio wave direction. In this case, the high frequency obtained from the tracking power feeding system is known. The tracking signal synthesized from the received signal controls the antenna driving device to automatically control the orientation of the antenna.

That is, the tracking power feeding system that has been conventionally used is a self-tracking monopulse system that synthesizes the received microwaves at a high frequency level (complex number, a trigonometric function of two or more waves). There are high-order mode method and multiple horn method.

In the higher-order mode system, the electromagnetic field induced in the waveguide of the primary radiator is the fundamental mode when the antenna is completely facing in the incoming wave direction, and the antenna deviates from the incoming wave direction. In this case, utilizing the fact that higher-order mode waves are generated in addition to the fundamental mode, this is a method that mainly detects the tilt of the antenna main beam direction with respect to the direction of the incoming wave from the TM ₀₁ component, and is equipped as a primary radiator, for example. The inside of the waveguide by combining the coupling hole output of the circular waveguide with Magic T
Tracking couplers for detecting the ₀₁ mode are often used.

In principle, the multiple horn system uses four horn radiators arranged in axial symmetry with respect to the antenna main beam axis, and produces four beams slightly inclined with respect to the antenna main beam axis. A method for obtaining error signals of azimuth angle and elevation angle from a sum signal and a difference signal synthesized at a high frequency level from a high frequency received signal of each radiator by using a hybrid circuit, and transmitting and receiving for communication using only these four radiators. There are known a four-radiator system in which reception for tracking and tracking are simultaneously processed, and a five-radiator system in which a main radiator for communication is placed on an axis and four dedicated radiators for tracking are arranged around the main radiator.

[0008]

With a microwave antenna mounted on a moving body, for example, an ambulance and other vehicles, the electromagnetic wave transmitted from, for example, an artificial satellite is tracked and received by a remote station while the vehicle is moving. When attempting to maintain communication, it is necessary to consider interference when a vehicle passes under obstacle slits arranged at equal intervals such as a power line. The energy I (θ) of the microwave passing through such a slit obstacle is proportional to the square of the amplitude that is a function of the angle θ from the slit to the receiving antenna. Can be represented.

[0009]

## EQU1 ## I (θ) = I (0) | sin {πD (sin θ) / λ} / {πD (sin
θ) / λ} | ²

Here, I (0) is the energy of the incident microwave, D is the width of the equally spaced slits, θ is the angle from the slit to the receiving antenna, and conditions other than width D are reflected waves and interference waves. There is no. The microwave energy represented by this formula is the Fast Fourier Transform (FFT)
It is nothing but the power when one time slit is considered.
That is, independently receiving the microwaves passing through the obstacles at equal intervals is equivalent to performing FFT expansion in the case of a fixed window in the time axis direction.

What is clear from this is that in the conventional monopulse system for synthesizing microwaves at a high frequency level,
The FFT expansion is independent under the condition that the independent receiving points have different potential changes with time, such as fading and propagation fluctuations caused by the antenna mounted on the vehicle moving in the standing wave. This means that the value obtained is wasted, and if combining with a trigonometric function (complex number) of two or more waves at a high frequency level, the linearity cannot be maintained and tracking may fail.

The object of the present invention is to prevent interference from radio wave obstacles such as power transmission lines when it is mounted on a mobile body and used, and the antenna itself determines the arrival direction of the radio wave and feeds it back to the tracking device. An object of the present invention is to provide a tracking antenna device capable of reliably and stably capturing the arrival direction of a radio wave.

[0013]

In order to solve the above-mentioned problems, a tracking antenna device according to the present invention has at least one directional main antenna element and an n-segment around the main antenna element. Two or more integer n directional sub-antenna elements that are fixed so as to form a detection system, a tracking drive device that integrally changes the directions of all these antenna elements, and n of the n-division detection system Receiving means for producing n detection outputs by independently detecting each high-frequency reception signal obtained from the sub-antenna element and reception signal power by comparison calculation processing based on the n detection outputs from the reception means. Detecting means for detecting the direction in which the maximum is detected, and control for feedback-controlling the tracking drive device so that the main antenna element faces the direction based on the detection result of the detecting means. It is characterized in that a stage.

According to a preferred embodiment of the present invention, the directional beam axes of the four sub-antenna elements are all slightly tilted at the same opening angle with respect to the main beam axis of the main antenna element. The antenna elements are arranged at equal angular intervals around the main beam axis to form a quadrant detection system having the main beam axis of the main antenna element as a coordinate axis, and the detection means includes the four sub-antennas. Among the elements, four signal components corresponding to the sum signal of the detection outputs of the received signals from two adjacent elements that are sequentially adjacent to each other around the main beam axis are used in the comparison calculation process.

According to a further preferred embodiment of the present invention, there is further provided an integrating means for time-integrating n detection outputs from the receiving means independently of each other, and four detecting means integrated by time by the integrating means. The output is used for comparison calculation processing by the detection means.

In the present invention, different from the conventional monopulse system, for example, the high-frequency reception signals from the four directional sub-antenna elements constituting the quadrant detection system are independently heterodyne-detected and obtained. The arrival direction of the radio wave is detected by comparison calculation processing based on the four detection outputs, and the tracking drive device is feedback-controlled. That is, for example, when n is 4, the heterodyne detection system is four independent systems, and since the four independent detection outputs obtained from the independent detection systems are subjected to the comparison calculation processing, the potential of the received radio wave is delayed. Independent detection outputs can be time-integrated individually even if they change over time, and since independent time average values can be compared with each other, the linearity is not destroyed by the synthesis process. It is possible to specify the direction of a signal whose direction of arrival is unknown from a moving body as absolute coordinates in space by comparing the power integration of the rectangular coordinates of the quadrant.

In the present invention, it is desirable to adopt a heterodyne detection system which can obtain a high S / N ratio in the tracking signal receiving system. More preferably, it is preferable to independently integrate a plurality of independent detection outputs obtained from the receiving means with each other over a certain delay time. This is because when detecting weak signal components existing in the radio waves from artificial satellites, the signal components have the same phase and the noise has random phase in order to detect the signal components buried in the noise. Because it is a good idea to utilize a certain fact. Random phase noise components are canceled by time integration, and only signal components can be extracted with high sensitivity.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The features and other details of the present invention will be described below in detail based on the illustrated embodiments. The embodiments described below do not limit the present invention,
Needless to say, the modifications that are obvious to those skilled in the art are also included in the technical scope of the present invention.

FIG. 1 is a functional block diagram showing the configuration of the main part of a tracking system in a tracking antenna device according to a preferred embodiment of the present invention, and FIG. 2 is a schematic perspective view showing an example of an antenna used in the present invention. FIG. 3 is a schematic perspective view showing another example of the same antenna.

In the tracking antenna device according to the present invention, at least one directional main antenna element and two or more positive numbers arranged around the main antenna element so as to form an n-segment detection system. Using n directional sub-antenna elements.

In the embodiment shown in FIG. 2, each of these antenna elements is composed of a helical antenna in which a beam mode helix is attached to a parabolic reflector, and is provided with a transmission / reception power feeding section used for original communication. The central helical antenna Hm is the main antenna element, and the four helical antennas Ha, Hb, Hc. Hd is a sub-antenna element provided with a power feeding unit for reception that is used for tracking. The reflectors of all these helical antennas are fixedly connected to one another and are preferably integrally molded.

With respect to the main beam axis of the main antenna Hm, the directional beam axes of the four sub-antennas Ha to Hd are all slightly inclined at the same divergence angle, and these four sub-antennas are mutually arranged around the main beam axis. A quadrant detection system having a main beam axis of the main antenna Hm as a coordinate axis at equal angular intervals is formed in a coordinate plane orthogonal to the main beam. The opening angle of each sub-antenna and the eccentric distance from the main antenna are determined by the characteristics of the type of antenna used, the half-value angle, and the interference characteristics with the adjacent antenna. The main antenna and the sub-antenna, together with their reflectors, are driven by a driving device D described later.
By (FIG. 1), it is possible to integrally control the drive in the azimuth (direction) and elevation (depression) directions.

On the other hand, in the embodiment shown in FIG. 3, this is realized by the Cassegrain antenna. That is, this Cassegrain antenna includes a main reflector Rm and a sub-reflector Rs that is arranged in a face-to-face relationship with the main reflector Rm. The main reflector Rm is aligned with the focus position of the sub-reflector Rs. Is fixed with a composite feeding element P incorporating five feeding elements. Arranged on the back of the main reflector Rm is a casing S of a quadrant detection device incorporating a reception system and a detection system described later.
Is.

The composite feeding element P is a transmitting / receiving feeding element Pm used as a main antenna element for original communication.
In the center, and receiving feed elements Pa, Pb, Pc, and Pd used for tracking as sub-antenna elements are arranged around the center at 90 degree intervals.
In this case, the transmitting / receiving main antenna element Pm is located on the focal point of the main reflector Rm, while the tracking sub-antenna elements Pa, Pb, Pc, Pd are equidistant from the focal point of the main reflector Rm. Because of the offset position, the directional beam axes of the four sub-antenna elements Pa to Pd are all oriented toward the direction of an even opening angle with respect to the main beam axis of the main antenna element Pm. The antennas constitute a quadrant detection system with the main beam axis of the main antenna Pm as a coordinate axis at equal angular intervals around the main beam axis in a coordinate plane orthogonal to the main beam. Each antenna element is
Since the composite feeding element P is attached to the Cassegrain antenna, when the directions of the antennas are changed by the driving device described later, the directions are changed all at once.

Incidentally, it is also possible to incorporate the quadrant detection system into an ordinary parabolic antenna by utilizing the above-mentioned composite feeding element P. In this case, for example, instead of the sub-reflector Rs of the Cassegrain antenna, the composite feed element P is replaced by the main reflector Rm.
It should be attached so as to face directly.

When the present invention is applied to a Cassegrain antenna or a parabolic antenna, it is preferable to use a horn type element having excellent directional characteristics as the main antenna element and the sub antenna element, especially in a high operating frequency range.
Of course, the antenna element used in the present invention is not limited to the above example, and is configured using various types of microwave directional antennas such as a Yagi antenna and a loop antenna depending on the polarization type of the radio wave to be received. It is possible to

FIG. 1 shows a functional circuit configuration of a quadrant detection / tracking system when the tracking antenna device of the present invention is constructed by using the antenna shown in FIG. Since the transmission / reception system for the original communication by the main antenna element is not much different from the known system, its illustration and detailed description are omitted.

This circuit includes sub-antennas Ha, Hb and H.
4 receivers Ra, Rb, R that independently detect the respective high-frequency received signals obtained from c and Hd
c, Rd (reception means), integration sections Fa, Fb, Fc, Fd (integration means) for independently independently time-integrating four independent detection outputs obtained from each reception section, and individual integration sections. A comparison calculation circuit CM (detection means) for detecting the arrival direction of the received radio wave showing the maximum power by the comparison calculation processing based on the four integrated detection outputs, and a tracking drive device based on the detection result by the comparison calculation circuit CM. And a control device CONT for feedback controlling D, whereby an azimuth motor Ma for changing the azimuth of the antenna via the drive device D and a depression / elevation angle so that the signal from the comparison operation circuit CM always has the maximum value. The elevation motor Me for changing is feedback-controlled.

The high-frequency reception signal detected by each receiving unit may be, for example, a carrier wave signal of a modulated radio wave used for communication by the main antenna, or may be a specially superimposed marker signal. Receivers Ra and R of each channel
In b, Rc, and Rd, each sub-antenna Ha, Hb, Hc,
The high frequency reception signals from Hd are independently mixed with the local oscillation signals to heterodyne-detect the intensity of each reception signal. It is needless to say that the four independent channels of this circuit are adjusted to have substantially the same characteristics by compensating and adjusting variations in characteristics of all elements from the sub antenna to the comparison operation circuit CM.

In FIG. 1, the rear stage side of each receiving section is assembled by a digital signal processing system converted by an analog / digital converter. The stable operation of the digital signal processing system and the local oscillation frequency control section of each receiving section is guaranteed by the integrated management by the microcomputer CPU.

In the illustrated embodiment, four sub-antennas H
Of the a, Hb, Hc, and Hd, the detection outputs of the reception signals from two sub antennas that are adjacent in order in the circumferential direction about the main beam axis of the main antenna Hm are mixers Mxa and Mx.
b, Mya, and Myb are respectively mixed, and a total of four sum signals obtained by the individual mixers are compared by the comparison operation circuit CM.

That is, when the antenna is viewed from the rear, the detection output derived from the high frequency reception signal by the sub antenna Ha located in the upper left part of the main antenna Hm is A, and the detection output derived from the high frequency reception signal by the sub antenna Hb also located in the upper right part. Let B be the detection output, the detection output from the high-frequency reception signal from the sub-antenna Hc located at the lower left is C, and the detection output from the high-frequency reception signal from the sub-antenna Hd located at the lower right is D. Mya produces an output corresponding to the sum signal (A + B), mixer Myb produces an output corresponding to the sum signal (C + D), and mixer Mxa produces a sum signal (A + C).
And the mixer Mxb produces a sum signal (B +
Produces an output corresponding to D).

In the comparison operation circuit CM, the sum signal (A + B)
And the sum signal (C + D) are compared to detect radio wave arrival information about the maximum power radiation position in the vertical direction, that is, in the direction in which the angle of depression and elevation of the antenna spreads.
+ C) and the sum signal (B + D) are compared to detect radio wave arrival information about the maximum power radiation position in the left-right direction, that is, in the direction in which the azimuth of the antenna spreads. In the comparison arithmetic circuit CM, three-dimensional information regarding the radio wave radiation position of the maximum power in space is generated from these information, and this is given to the control device CONT as feedback information, and the control device CONT drives the motor via the drive device D. M
Feedback control of a and Me. In this way
Accurate tracking operation is performed by constantly comparing the sum signal strengths of the detected outputs in the up and down and left and right directions and giving a drive command to direct the antenna to the side with a higher received signal strength and feedback controlling the tracking drive system. I am doing it.

In the present embodiment, the above-mentioned sum signal is a signal obtained by mixing the detection output from the receiving section with the integrating section after time integration. For example, when a received signal containing a signal component sufficiently higher than noise can be obtained from the sub antenna,
As shown by the broken line in FIG. 1, it is also possible to directly input the detection output from each receiving section to the mixer without using an integrating section and give feedback only by relative comparison of signal intensities. When the intensity of the signal component in the signal is insufficient with respect to the noise level, the detection output from each receiving unit is time-integrated individually and independently over an arbitrary time set according to the propagation distance, for example. As a result, random noise components of phases are canceled out, and only the signal component can be extracted with high sensitivity. Moreover, since this is processed independently for each channel, as described above, independent receiving points such as fading and propagation fluctuations that occur when the antenna mounted on the vehicle moves in the standing wave. However, there is an advantage that the linearity is maintained even under the condition that the potential changes are different with respect to time, and there is no possibility of tracking failure.

[0035]

As described above, according to the present invention,
It is not necessary to vibrate the antenna itself to detect the direction of arrival of radio waves, and compared with the conventional monopulse type tracking antenna, it is subject to interference from radio wave obstacles such as power transmission lines especially when it is mounted on a moving body and used. Since the antenna itself determines the arrival direction of the radio wave and feeds it back to the tracking device, it is possible to provide a tracking antenna device capable of reliably and stably capturing the arrival direction of the radio wave.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration of a main part of a tracking system in a tracking antenna device according to a preferred embodiment of the present invention.

FIG. 2 is a schematic perspective view showing an example of an antenna used in the present invention.

FIG. 3 is a schematic perspective view showing another example of the antenna similarly used in the present invention.

[Explanation of symbols]

Hm: Main helical antenna (main antenna element) Ha to Hd: Sub-helical antenna (sub-antenna element) Rm: Main reflector Rs: Secondary reflector P: Composite feeding element Pm: Main feeding element (main antenna element) Pa to Pd: Sub feeding element (sub antenna element) Ra to Rd: receiving unit (receiving means) Fa to Fd: Integrator (integrator) CM: Comparison operation circuit (detection means) CONT: control device (control means) D: Tracking drive device Ma: Azimuth motor Me: Elevation motor Mxa, Mxb, Mya, Myb: Mixer CPU: Microcomputer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masuhisa Ta             2-3-6 Fushiki Kofu, Takaoka City, Toyama Prefecture F-term (reference) 5J021 AA01 AA06 AA12 AB02 AB07                       AB09 BA01 CA06 DA02 EA05                       FA13 FA14 FA17 FA19 FA21                       FA29 GA02 HA03 HA10 JA00                 5J046 AA02 AA04 AB05 AB12 AB18                       MA00

Claims (3)

[Claims] 1. At least one directional main antenna element and two or more integer n directional sub-antennas fixed so as to form an n-segment detection system around the main antenna element. Elements, a tracking drive device that integrally changes the orientations of all of these antenna elements, and heterodyne detection independently for each high-frequency reception signal obtained from the n sub-antenna elements of the n-division detection system. n
Receiving means for producing a plurality of detection outputs, detecting means for detecting a direction in which the received signal power is maximized by comparison calculation processing based on the n detection outputs from the receiving means, and based on a detection result of the detecting means. A tracking antenna device comprising: a control unit that feedback-controls the tracking drive device so that the main antenna element faces the direction. 2. The directional beam axes of the four sub-antenna elements are all slightly tilted at the same divergence angle with respect to the main beam axis of the main antenna element, and these four sub-antenna elements are arranged around the main beam axis. The quadrant detection system is arranged at equal angular intervals to each other and has the main beam axis of the main antenna element as a coordinate axis, and the detection means are adjacent to each other in order around the main beam axis among these four sub antenna elements. The tracking antenna device according to claim 1, wherein four signal components corresponding to a sum signal of detection outputs of received signals from two each are used for comparison calculation processing. 3. Further comprising an integrating means for time-integrating the four detection outputs from the receiving means independently of each other, and n detection outputs time-integrated by the integrating means are used for comparison calculation processing by the detecting means. The tracking antenna device according to claim 1, wherein the tracking antenna device is used.