JP5003337B2 - Broadcast antenna device - Google Patents

Description

  The present invention relates to an omnidirectional broadcast antenna apparatus suitable for transmitting a plurality of broadcast waves having different radio wave frequencies.

  The conventional broadcasting antenna apparatus includes a plurality of (N) antenna elements A and B arranged at equal angular intervals on a cylindrical surface C having a radius R, and first and second antennas assigned different radio frequencies. The antenna elements A and B of the multi-plane synthetic antenna are alternately arranged on the cylindrical surface C. Also, the antenna element gives a phase difference determined for each polyhedral synthetic antenna and feeds the phase difference, thereby suppressing interference between the polyhedral synthetic antennas and radiating two broadcast waves having different frequencies omnidirectionally. (For example, refer to FIG. 4 of Patent Document 1 and FIG. 1 of Patent Document 2).

JP 2001-127541 A JP 2000-223941 A

  However, in a conventional broadcast antenna apparatus, antenna elements each composed of a plurality of multi-plane synthetic antennas to which different radio frequencies are assigned are circularly arranged on a cylindrical surface in a predetermined order on a cylindrical surface having a radius R. And since the omnidirectional radiation pattern of radio waves obtained by combining the radio waves radiated from each antenna element in the air differs between radio frequencies with different antenna element arrangements, the deviation of the level of the omnidirectional radiation pattern is It depends on the type. Therefore, the reception side receives radio waves with high and low levels, and depending on the reception state, frequencies that appear on the TV and frequencies that do not appear may appear.

  In order to achieve the above object, the present invention is configured as follows.

The broadcast antenna device according to the first aspect of the present invention provides a multi-plane composite antenna composed of a plurality of panel antennas to which different radio frequencies are assigned, on the cylindrical surface of different radii (Ra, Rb), respectively, on the outer side of the cylindrical surface. And one of the multi-surface synthetic antennas on the cylindrical surface of one radius Ra and one of the multi-surface synthetic antennas on the other cylindrical surface of the other radius Rb adjacent to the left or right is located outside the cylindrical surface. One of the multi-surface synthetic antennas on the cylindrical surface with the one radius Ra and one of the multi-surface synthetic antennas on the cylindrical surface with the other radius Rb adjacent to the left or right is the outside of the cylindrical surface. The direction is different for the.

In the invention of claim 2 broadcast antenna device according to claim 1, a plurality of antenna element constituting the polygon synthetic antenna respectively is 18 ° or 36 ° of those feeding phase difference at the center frequency

According to a third aspect of the present invention, in the broadcast antenna device according to the first or second aspect , the plurality of multi-surface composite antennas to which different radio frequencies are assigned are provided in multiple stages on the same axis, and are provided in multiple stages for each radio frequency. A multi-sided synthetic antenna is formed.

  As described above, according to the present invention, the omnidirectional pattern between different frequencies can be reduced even when the first and second multi-surface synthetic antennas that transmit two broadcast waves having different radio frequencies are alternately arranged. The broadcast antenna device can be constructed.

A first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a broadcast antenna apparatus. Here, as the first and second multi-plane synthetic antennas, as shown in an exploded view in FIG. 2, the omnidirectional first 20-plane synthetic antenna 10 (with 20 antenna elements A (A1 to A20)) ( 2 (see FIG. 2 (a)) and a non-directional second 20-plane synthetic antenna 50 (see FIG. 2 (b)) having 20 antenna elements B (B1 to B20), respectively. In addition, each peripheral surface is arranged coaxially.

  As shown in a part of the antenna arrangement in FIG. 3, the first and second 20-plane composite antennas 10 and 50 have 20 antenna elements A1 to A20 and B1 to B20 having the same center with radii Ra and Rb, respectively. The antenna surface faces outward on the cylindrical surfaces C1 and C2 of the shaft.

  The first 20-plane composite antenna 10 has the antenna elements A1 to A10 offset to the left by a predetermined dimension da in the tangential direction of the cylindrical surface toward the left side, and the second 20-plane composite antenna 50 has antenna elements B1 to B20. Is offset to the right by a predetermined dimension db in the tangential direction of the cylindrical surface.

Further, the first 20-sided polyhedral synthetic antenna 10 and the second 20-sided polyhedral synthetic antenna 50 are arranged at equiangular intervals (18 ° intervals), and the first antenna and the second antenna are in the same direction, or Θ2 Alternatively, they are arranged alternately with a predetermined angle of Θ3.
Here, the angles Θ2 and Θ3 may be 0 °. The cylindrical surfaces C1 and C2 are spatially defined surfaces.

  As shown in FIG. 1, the first and second 20-plane combined antennas 10 and 50 are fed with phase difference via phase shifters 11 to 30 and 51 to 70, respectively, to correct the offset of the antenna elements. The broadcast waves having different radio frequencies fa and fb are set to be transmitted. In the figure, reference numerals 31 and 71 denote broadcast wave transmitters having the radio wave frequencies fa and fb.

  Next, regarding the internal configuration of each of the antenna elements A and B constituting each of the 20-plane combined antennas 10 and 50, in the present embodiment, a case where a four-element twin loop antenna is used will be described below.

4 (a), 4 (b), and 4 (c) show the planar configuration, side surface configuration, and cross-sectional configuration.
The four-element twin-loop antenna 74 has a flat plate-like reflector 72 in which both edges in the longitudinal direction are bent at approximately 45 °. On the reflector 72, an arc-shaped loop antenna element portion 73 having a circumference L of approximately one wavelength λ of the radio wave frequencies fa and fb is formed. A double loop antenna 74 in which four loop antenna element portions 73 are formed is provided in parallel to the main surface. Thereby, the radio wave radiated from the double loop antenna 74 is configured to be transmitted with a single directivity in a direction perpendicular to the main surface of the reflector 72.

  The protective cover (raidome) 75 in FIG. 4 is provided so as to cover the double loop antenna 74, and in order to make the internal structure of the double loop antenna 74 easy to understand, a part of the protective cover (raidome) 75 is deleted. It is a figure. The protective cover 75 protects the double loop antenna 74 from rain and wind, snow, and dust. The loop antenna element can be provided with a predetermined dimension offset from the center of the reflector main surface.

  As described above, the antenna elements A and B of the first and second 20-plane combined antennas 10 and 50 are fed with phase differences via the phase shifters 11 to 30 and 51 to 70, respectively, and broadcasts having different radio frequencies. A non-directional radiation pattern is obtained by radiating waves and combining the radiated radio waves.

Specifically, for example, 20 antenna elements A constituting the first 20-plane composite antenna 10 are fed with a phase difference of + 18 ° or + 36 ° around A1 to A20, respectively. In contrast, the 20 antenna elements B constituting the second 20-plane composite antenna 50 are fed with a phase difference of −18 ° or −36 ° around B1 to B20, respectively.
According to the broadcast antenna device configured as described above, the two broadcast waves, which are different from the radio wave frequencies fa and fb, from the first and second 20-plane composite antennas 10 and 50, respectively, independently and individually. The deviation of the omni-directional pattern can be reduced and transmitted.

  On the other hand, in order to increase the transmission power of each multi-plane synthetic antenna, in the broadcast antenna apparatus in which the first and second 20-plane synthetic antennas are alternately arranged, the multi-stage coaxial antenna is arranged in multiple stages in the vertical direction of the broadcast antenna apparatus. What is necessary is just to make it a multi-surface synthetic | combination antenna (4 steps | paragraphs 20 surface synthetic | combination antenna etc.), and to enlarge the antenna area for every radio wave frequency, and to raise the antenna gain (refer FIG. 5).

A four-element twin loop antenna was used for the first 20-plane antenna and the second 20-plane antenna. The first antenna had a frequency of 521 MHz, and the second antenna had a frequency of 545 MHz.
The mounting radius Ra of the first 20-plane antenna is 3.78 m and the offset da is 0.24 m, the mounting radius Rb of the second 20-plane antenna is 3.61 m, and the offset db is 0.21 m. Further, the horizontal directivity was calculated by setting the angle Θ2 to 3 °, the phase difference feeding to -18 ° for the first 20-plane antenna, and + 18 ° for the second 20-plane antenna.

The calculated result is shown in FIG. The solid line has a frequency of 521 MHz and the broken line has a frequency of 545 MHz. Compared with the horizontal directivity (FIG. 7) according to the conventional arrangement, it can be seen that the deviation in directivity between the frequencies of 521 MHz and 545 MHz is small.
Here, FIG. 6 and FIG. 7 are represented by the electric field strength ratio. Therefore, it is necessary to take 20 logs in order to express with power (dB display).
In addition, this invention is not limited to the numerical value of embodiment mentioned above. For example, each parameter (angle Θ2, Θ3, mounting radius Ra, Rb, offset da, db, loop antenna element circumference L, etc.) is appropriately selected based on the directivity obtained as shown in FIG. What is necessary is just to obtain a desired characteristic.

The layout of an antenna element which shows the schematic structure of the broadcast antenna apparatus based on one Embodiment of this invention. The equivalent block diagram of the broadcast antenna apparatus shown in FIG. The figure which shows arrangement | positioning of the broadcast antenna apparatus shown in FIG. The figure which shows the structural example of the antenna element which comprises a polyhedral synthetic | combination antenna. The figure which shows another example of arrangement | positioning of the antenna element which comprises a multistage polyhedral synthetic | combination antenna. In this invention, it is a graph showing the directivity in frequency 521MHz and 545MHz. It is a graph showing the directivity in the frequency of 521 MHz and 545 MHz in the conventional polyhedral synthetic antenna.

Explanation of symbols

10 1st 20 surface synthetic | combination antenna 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 Phase shifter (For phase difference feeding)
31 Transmitter (Radio Frequency fa)
50 Second 20-side synthetic antenna 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70 Phase shifter (For phase difference feeding)
71 Transmitter (Radio Frequency fb)
72 Reflector 73 Loop antenna element portion 74 Double loop antenna 76 Antenna mounting column A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20 Antenna element B1, B2, B3, B4, B5, B6, B7, B8, B9, B10, B11, B12, B13, B14, B15, B16, B17, B18, B19, B20 Antenna element C1 Radius Ra cylindrical surface C2 Cylindrical surface with radius Rb

Claims (3)

  A multi-plane synthetic antenna composed of a plurality of panel antennas to which different radio frequencies are assigned is arranged on a cylindrical surface having a different radius (Ra, Rb) at a predetermined angle toward the outside of the cylindrical surface, and one radius One of the multi-surface synthetic antennas on the cylindrical surface of Ra and one of the multi-surface synthetic antennas on the cylindrical surface of the other radius Rb adjacent to the right or left face substantially in the same direction toward the outside of the cylindrical surface. Broadcasting characterized in that one of the multi-surface combined antennas on the cylindrical surface with the radius Ra and one of the multi-surface combined antennas on the other cylindrical surface with the radius Rb adjacent to the left or right are different in direction toward the outside of the cylindrical surface. Antenna device. 2. The broadcast antenna apparatus according to claim 1 , wherein the plurality of antenna elements constituting each of the multi-surface synthetic antennas are fed with a phase difference of 18 ° or 36 ° at a center frequency. Different radio frequencies of the plurality of multi synthesized antenna assigned each other, each provided in multiple stages coaxially according to claim 1 or 2, characterized in that to form a multi-stage multi synthetic antenna at the each radio frequency Broadcast antenna device.

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