JPH05145336A - Multi-beam array antenna - Google Patents

Abstract

PURPOSE:To greatly reduce a power loss of a signal when plural signals are sent or received. CONSTITUTION:Lots of circular patch antennas 2 are arranged on circumferences of plural concentric circles in a circular array antenna 1 and the beam of the circular array antenna 1 is tilted in plural directions by installing the patch antennas 2 of each array in a predetermined direction. When the antenna is operated as a transmission antenna, transmission power is sent to a probe 6 via a coaxial connector 7 and a radio wave radiates in a radial line 5 comprising a metallic plate 2c, the surface of a bottom plate 4 and an inner wall of a ring 3. A feeding pin 2e is fitted to a feeding point 2d of each circular patch antenna 2 toward the radial line 5, a radio wave propagated through the radial line 5 is absorbed by the feeding pin 2e and radiates further from the circular patch antenna 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam array antenna that transmits or receives radio waves in two or more directions.

[0002]

2. Description of the Related Art A multi-beam antenna is an antenna of a type that radiates radio waves from a single antenna in a plurality of different directions, and has recently been used for purposes such as satellite communication or satellite broadcast reception. Hereinafter, two conventional examples will be described with reference to the drawings.

As a first example, there is a multi-beam offset parabolic antenna as shown in FIG. 7 (a) is a plan view thereof, and FIG. 7 (b) is a sectional view taken along the line DD of FIG. 7 (a). In these figures, each power supply terminal 1
A transmission output from a transmission system device (not shown) is applied to 2 and 13. Then, the radio waves radiated from the respective primary radiators 10 and 11 are reflected by the circular and curved reflecting mirror 9 to become radiation beams 14 and 15, respectively. In this case, the radiation directions of the radiation beams 14 and 15 are determined by the incident angle of each radio wave emitted from the primary radiators 10 and 11 to the reflecting surface 9 and the installation angle of the reflecting mirror 9. Hereinafter, the electromagnetic wave emitted from the antenna in a desired direction is referred to as a radiation beam. In the figure, a multi-beam offset parabolic antenna having radiation beams in two directions is shown, but the number of radiation beams differs depending on the purpose of use of the antenna.

Next, FIG. 8 is a plan view of a phased array antenna which is a second conventional example. A dipole antenna, a patch antenna or the like having a wide radiation pattern is generally used for the element antenna 17 shown in the figure, and a large number of these are regularly arranged in a linear or planar shape. The beam forming circuit 16 combines the amplitude and phase setting circuit of the feed power supplied to each element antenna 17, the power distributor that distributes the feed power to each element antenna, and the received power at each element antenna. It is composed of a power combiner and the like. When transmitting a radio wave with this multi-beam antenna, transmission power from the transmitter is applied to the power supply terminal 18, and a control signal for setting the beam direction and the number of beams is supplied to the beam control terminal 19. The beam forming circuit 16 is operated by this control signal, the beam direction and the number of beams are set, and the respective radiation beams 20 and 21 are obtained. The number of radiation beams depends on the purpose of use of the antenna.

[0005]

By the way, the multi-beam offset parabolic antenna of FIG.
Since the primary radiators 10 and 11 are required, the structure and weight of the radiators become large.

Further, the phased array antenna of FIG. 8 has the drawbacks that the structure of the beam forming circuit 16 is complicated and the passage loss for high frequency signals is large. For example, in the beam forming circuit 16, the loss in the phase shifter that sets the feeding phase to each element antenna 17 is 2 to 3 dB. Therefore, when the phased array antenna is used for transmission, the waste of transmission power is large, and when it is used for reception, the noise figure becomes large and the C / N ratio of the received signal deteriorates. is there. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to configure a multi-beam antenna in which high frequency signal power loss is extremely small.

[0007]

In order to solve the above-mentioned problems, an element antenna, a conductive upper plate on which the element antenna is installed, and a cylindrical shape in which the upper plate is arranged at one end surface thereof. Of the conductive member, and a radial line formed by a conductive plate-shaped bottom plate constituting the other end surface of the conductive member, the element antenna is arranged on the circumference of a plurality of concentric circles, the same Each of the element antennas included in the row is installed at an angle such that radio waves are in-phase combined in a specific direction with respect to a normal direction of the upper plate.

[0008]

According to the above multi-beam array antenna, in the conductive upper plate, the element antennas are arranged on the circumference of a plurality of concentric circles, and each element antenna has a plurality of specific elements in the normal direction of the upper plate. A multi-beam antenna is configured by installing the antennas at an angle such that radio waves are in-phase combined in the direction. Further, in the radial line formed by the upper plate, the cylindrical conductive member, and the plate-shaped bottom plate having conductivity, from the transmission radio wave or the element antenna propagating from the power feeding system device installed on the back surface of the bottom plate to the element antenna. The received radio wave propagating to the receiving system device is excited.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a plan view showing the basic structure of an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line AA of FIG. However, FIGS. 1A and 1B are diagrams schematically showing the basic configuration of the present invention, and the numbers and shapes of the circular patch antenna 2 and the feeding pin 2e are accurate for simplification of description. Not shown in.

In FIG. 1B, a circular array antenna 1 is fixed to a ring 3, and the ring 3 is attached to a bottom plate 4. The ring 3 and the bottom plate 4 are made of metal or a material obtained by applying metal plating to engineering plastics. At this time, the radial line 5 is formed by the metal plate 2 c extending on the back surface of the circular array antenna 1, the inner wall of the ring 3, and the surface of the bottom plate 4. Also,
In the central portion of the bottom plate 4, the probe 6 penetrates the bottom plate 4, one end of which is connected to the coaxial connector 7 on the back surface of the bottom plate 4 and the other end projects from the surface of the bottom plate 4 by a quarter wavelength. ing.

A large number of circular patch antennas 2 are arranged on the surface of the circular array antenna 1. In this arrangement, a plurality of concentric circles are set on the circular array antenna 1, and the circular patch antennas 2 are arranged at equal intervals on the circumference of these concentric circles. In this case, the size of the circular array antenna 1 and the number of rows of the circular patch antennas 2 differ depending on the application of the multi-beam array antenna. Also,
The installation direction of the circular patch antenna 2 is determined by the number of radiation beams and the direction of radiation beams of the designed multi-beam array antenna. However, the circular patch antennas 2 included in the same row are installed at an angle such that radio waves are in-phase combined in a certain direction with respect to the normal direction of the circular array antenna 1. For example, when designing a multi-beam array antenna that has N rows of circular patch antennas on the circular array antenna 1 and radiates beams in two specific directions, each circle in a certain x rows of N rows is designed. The patch antenna 2 is installed at an angle such that radio waves are in-phase combined in one radiation beam direction, and each circular patch antenna 2 in the remaining Nx rows is in-phase combined in another radiation beam direction. Install at such an angle. Thus, by installing the circular patch antenna 2, it is possible to radiate a beam in two directions. Hereinafter, tilting the radiation beam direction of the circular array antenna 1 with respect to the normal direction of the antenna surface is referred to as beam tilt. The beam tilting method in the array antenna using the radial line 5 is shown in the following paper and the patent publication.

A: 1991 Spring Meeting of the Institute of Electronics, Information and Communication Engineers, B-66 Haneishi et al., “Beam-tilt type radial microstrip antenna” b: Published patent publication Hei 2-189008 Circularly polarized antenna device

FIG. 2 is a diagram showing a configuration of a circular patch antenna 2 for transmitting right-handed circularly polarized waves used in this embodiment. FIG. 2A is a plan view of the circular patch antenna 2 and FIG. (b) is a BB line sectional view of (a). The circular patch 2b in this embodiment is formed on the surface of the dielectric substrate 2a by a method such as etching. The feeding pin 2e is attached to the feeding point 2d of the circular patch 2b by a method such as soldering, penetrates the dielectric substrate 2a, and is inserted into the radial line 5. Here, the position of the feeding point 2d,
The shape of the cutout 2f of the circular patch 2b is determined by the conditions for transmitting right-handed circularly polarized waves.

Next, the function of the cutout portion 2f of the circular patch antenna 2 shown in FIG. 2 will be described. In the circular patch antenna 2 operating in the TM ₁₁ mode, when the cutout portion 2f is not formed, the orthogonal resonance modes are doubly degenerated, and the linearly polarized wave of a certain resonance frequency is generated.
However, when the cutout portion 2f is formed in the circular patch antenna 2, the cutout portion 2f has a function of separating orthogonal resonance modes, and the frequencies for the two resonance modes change to different frequencies. At that time, at an intermediate frequency between these two frequencies, a 90 ° phase difference occurs in the excitation phase, and circular polarization occurs.

The principle of beam tilt by adjusting the installation direction of the element antenna will be described with reference to FIG. Figure 3
(A) is a plan view of two right-handed circularly polarized wave patch antennas having different installation directions from each other, and (b) is a sectional view taken along line CC in (a). Here, the circular patch antennas 21 and 22 that emit right-handed circularly polarized waves are arranged at intervals d on the x-axis. Maximum radio wave emission direction (main beam direction)
In order to make the angle θ with respect to the z-axis, it is sufficient to feed the circular patch antennas 21 and 22 so that the phases of the radio waves radiated by the circular patch antennas 21 and 22 have the same phase in the θ direction. The radio waves radiated by the circular patch antennas 21 and 22 are plane waves at a sufficiently long distance. When the circular patch antennas 21 and 22 are fed in the same phase and each radiated radio wave is observed at a sufficiently long distance in the θ direction, The respective radio waves have the same amplitude, and a phase difference corresponding to the distance difference S shown in the figure occurs. That is, when the circular patch antenna 21 is used as a reference, the phase of the radio wave radiated from the circular patch antenna 22 is advanced by a phase difference corresponding to the distance difference S. Therefore, if power is supplied so that the radio wave radiated by the circular patch antenna 22 is delayed by the phase difference corresponding to the difference S in distance, the phase of the radio wave radiated by the circular patch antenna 22 will be the phase of the radio wave radiated by the circular patch antenna 21. A maximum radiation beam is obtained in the θ direction because it matches the phase in the θ direction. That is, the main beam is directed in the θ direction. Here, when the phase difference corresponding to the difference S in distance is β, β is given by the following equation.

[0016]

[Formula 1] β = −360 · S / λ = −360 · d · sin θ / λ [degree]

As an example, when the element spacing d is 0.55λ and the beam tilt angle θ is 50 degrees, the phase β is -151.7.
Degree is required. Here, λ is the wavelength of the radiated radio wave.

The phase difference β corresponding to the difference S in distance can be realized by using a phase shifter, but when the polarization of the radio wave is circular polarization, it can be easily beamed by rotating a circular patch antenna. Tilt is possible. In the figure,
The circular patch antenna 22 is rotated by an angle corresponding to the phase difference β with respect to the circular patch antenna 21. In this state, the circular patch antenna 22
The phase of the radio wave radiated by is equal to the phase of the radio wave radiated by the circular patch antenna 21. Therefore, when the radio waves emitted by the circular patch antennas 21 and 22 are combined,
Maximum radiation is obtained in the direction. Although an example of right-handed circular polarization is shown here, it can be applied to left-handed circular polarization and linear polarization by changing the type of patch antenna or the arrangement of patch antennas.

FIG. 4 is a plan view showing a more detailed structure of this embodiment, which is an example in which eight circular patch antennas 2 are arranged on concentric circle lines. When the row closest to the center of the circular array antenna 1 is the first row, the number of circular patch antennas 2 in the first row is 6, and the number of circular patch antennas 2 in the nth row is 6n. It has become. However, n is a positive integer of 8 or less. The column spacing and the element spacing on the concentric circle lines are determined mainly by the beam tilt angle of the circular array antenna 2 designed,
For example, when a beam tilt of about 50 degrees is performed, the element spacing is about 0.55λ. In the array antenna, the radiation from each element antenna (the circular patch antenna 2 in this embodiment) is combined in phase to maximize the radiation in a specific direction, but depending on the arrangement interval of the element antennas. , A beam of the same size as the main beam may be generated in a direction different from the desired direction of the main beam,
This is called a grating lobe.

FIG. 5 is a circular array antenna 1 shown in FIG.
In FIG. 5, the radiation pattern calculation result is obtained when the beam tilt angle of the odd-numbered columns is set to 0 degree and the beam tilt angle of the even-numbered rows is set to 30 degrees.

Next, the operation of this embodiment will be described with reference to FIG. First, transmission power from a transmission system device (not shown) is supplied to the probe 6 via the coaxial cable 8 and the coaxial connector 7, and extends to the back surface of the circular array antenna 1 and the metal plate 2c and the bottom plate 4 are provided. Is radiated into the radial line 5 constituted by the surface of the ring and the inner wall of the ring 3, and propagates while being completely reflected. Further, the radio wave propagating through the radial line 5 is absorbed by the power feeding pin 2e and further radiated from the circular patch antenna 2.

The radio waves radiated from the probe 6 have the same phase at the feed pins 2e of the circular patch antennas 2 on the same row, but the feed pins 2e of the circular patch antennas 2 on two different rows each have the same phase. The phases of the radio waves absorbed by are different. That is, the circular patch antennas 2 in the outer row
The phase of the radio wave absorbed in the power feeding pin 2e of 1 is delayed. Therefore, in forming the circular array antenna 1 beam-tilted in one direction, in order to make the radio waves radiated from the circular patch antennas 2 have the same phase, when the circular patch antennas 2 are formed, Power supply pin 2e
The installation direction of the circular patch antenna 2 may be designed so as to correct the phase of the radio wave absorbed in. As described above, the beam can be emitted in a plurality of directions. Although the operation in the transmission state according to the embodiment of the present invention has been described above, the same applies to the operation in the reception state.

As another embodiment, when the beam directions of the multi-beam antenna are designed to be extremely close to each other, a wide-angle beam can be formed. Figure 6
In the circular array antenna 1 having a 12-row configuration in which the number of elements in the first row is 8 and the number of elements in the n-th row is 8n, the design beam tilt angle from the first row to the eighth row is 55 degrees, It is a calculation result of a radiation pattern when the design beam tilt angle of the 9th row and the 10th row is 50 degrees, and the design beam tilt angle of the 11th row and the 12th row is 45 degrees. In this case, it is possible to form a radiation pattern having a full width at half maximum of about ± 10 degrees centered on the beam tilt angle of 50 degrees.

In the above embodiment, the case where the circular patch antenna is used as the element antenna has been described. A helical antenna, a spiral antenna, or the like can be used as the other element antenna.

As described above, the multi-beam array antenna of the present invention does not require a reflector and a primary radiator, and is composed of a circular array antenna, a ring for mounting it, and a bottom plate. It can be made flat and lightweight.

Further, since the power loss of the high frequency signal is extremely small, the waste of the transmission power is small in the transmission, and the deterioration of the C / N ratio of the received signal is small in the reception.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention and its A
It is a sectional view taken along line A-.

FIG. 2 is a plan view of a circular patch antenna that transmits right-handed circularly polarized waves and a cross-sectional view taken along line BB thereof.

FIG. 3 is a plan view of two beam-tilted circular patch antennas and a sectional view taken along the line CC.

FIG. 4 is a plan view of a more detailed circular array antenna of this embodiment.

FIG. 5 is a radiation pattern diagram for one calculation result of a multi-beam array antenna having main beams in two directions.

FIG. 6 is a radiation pattern diagram for one calculation result of an array antenna forming a wide-angle beam.

FIG. 7 is a plan view of a multi-beam offset parabolic antenna which is a conventional device and a cross-sectional view taken along the line DD of FIG.

FIG. 8 is a plan view of a phased array antenna which is another conventional device.

[Explanation of symbols] 1 circular array antenna 2 circular patch antenna 2c metal plate 3 ring 4 bottom plate 5 radial line

Claims (1)

[Claims] 1. An element antenna, a conductive upper plate on which the element antenna is installed, a cylindrical conductive member arranged so that the upper plate is one end surface, and the other end surface of the conductive member. And a radial line formed by a plate-shaped bottom plate having a conductive property, the element antenna is arranged on the circumference of a plurality of concentric circles, each of the element antennas included in the same row, the A multi-beam array antenna characterized by being installed at an angle such that radio waves are in-phase combined in a specific direction with respect to the normal direction of the upper plate.