JPH0669726A - Radial line ring antenna - Google Patents

Abstract

PURPOSE:To provide a radial line ring antenna where a reflection loss is considerably small. CONSTITUTION:A conductor pin 7 disposed projectingly in a radial waveguide 4 is electromagnetically connected with a transmission wave which advances in the waveguide 4. Thus, a radiation element is excited. Since a reflected wave from the conductor pin 7 is sequentially arranged on a prescribed spiral line regulated on a dielectric substrate, it is returned to the center of the radial waveguide 4 with delay. Thus, antenna efficiency substantially improves without being affected by the reflected wave by one conductor pin 7.

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to, for example, a planar antenna for receiving satellite broadcasts, etc., and more particularly to a radial line ring antenna provided with a radial waveguide.

[0002]

2. Description of the Related Art As is well known, in recent years, various planar antennas have been developed and put into practical use with the start of satellite broadcasting. Some planar antennas of this type are provided with a radial waveguide formed by arranging an upper circular conductor plate and a lower circular conductor plate in parallel and facing each other and short-circuiting the periphery thereof.

As a planar antenna using such a radial waveguide, for example, a plurality of through holes arranged concentrically in an upper circular conductor plate are formed, and an insulator is interposed in each of these through holes to form a helical antenna. A helical antenna has been developed in which one end of an element is arranged so as to project into a radial waveguide. Such a helical antenna receives right-handed circularly polarized waves or left-handed circularly polarized waves corresponding to the winding direction of each helical element, synthesizes them while propagating in the radial waveguide, and feeds them to the feeding point of the radial waveguide. Will be collected in the center.

[0004]

By the way, when the above-mentioned conventional planar antenna is viewed as a transmission system, a transmission wave fed from the center of the radial waveguide travels radially toward the periphery, and this causes the transmission of the helical element. The helical element is picked up at one end, that is, a pin arranged so as to project into the radial waveguide, and thereby the helical element is excited.

However, at the time of this pickup, a part of the transmitted wave is reflected by the pin and becomes a reflected wave returning to the power feeding section. Therefore, when the helical elements are arranged on the concentric circles, the reflected waves from each pin return to the feeding point all at once, and the reflection loss becomes significantly large. As a result, there is a problem that a standing wave is generated and the antenna efficiency is lowered. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radial line ring antenna with extremely small reflection loss.

[0006]

According to a first aspect of the present invention, there is provided a base plate formed on a lower surface of a dielectric substrate, and a circular conductor plate which is arranged in parallel and opposed to the base plate and serves as an antenna base. A radial waveguide having a radial waveguide and a power feeding unit for supplying electric power to the radial waveguide, and a plurality of radiation elements that are formed on the upper surface of the dielectric substrate and generate circular polarization; Excitation means that penetrates the dielectric substrate and projects into the radial waveguide is provided at one end, and the excitation means is sequentially arranged on a predetermined spiral line defined on the upper surface of the dielectric substrate. It is characterized by that.

According to a second aspect of the present invention, the radiating element includes a straight path of a predetermined length extending from the starting end,
There is a curved path that is wound to the left or right through this straight path, and the straight path is formed on the upper surface of the dielectric substrate so as to face the center direction of the radial waveguide.

[0008]

According to the present invention, the exciting means projecting into the radial waveguide is electromagnetically coupled to the transmission wave traveling in the waveguide, whereby each radiating element is excited. Here, the reflected wave from the projecting excitation means is returned to the center of the radial waveguide with a sequential delay because the excitation means is arranged on a predetermined spiral line defined on the dielectric substrate. Therefore, the reflection loss is reduced because it is substantially affected only by the reflected wave of one exciting means.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective sectional view showing the overall structure of an embodiment of the present invention. In these figures, 1 is a frame of a circular conductor plate which constitutes the rear surface of this antenna. Reference numeral 2 is a base plate which is arranged in parallel on the upper surface side of the frame 1 with a predetermined gap therebetween. Reference numeral 3 is a low foam dielectric plate that is filled in the gap between the frame 1 and the base plate 2. These elements 1 to 3 form a radial waveguide 4.

Reference numeral 5 is a printed circuit board having a dielectric layer of thickness L on the base plate 2. That is, the lower surface side of the printed circuit board 5 is the base plate 2, while the plurality of ring elements 6 formed by etching are arranged on the upper surface side based on a predetermined positional relationship. The ring element 6 is
A conductor path having a line length corresponding to one wavelength of the used frequency is formed in a spiral shape, and the structure and the arrangement position will be described later.

Reference numeral 7 denotes a probe pin which is connected to one end of the ring element 6 and is inserted through the printed board 5 and the ground plane 2. The structure of the probe pin will be described later together with the structure of the ring element 6. Reference numeral 8 is a small circular hole formed in the base plate 3 for projecting the probe pin 7. Reference numeral 9 is a spacer formed of a highly foamed dielectric material having a dielectric constant equivalent to that of air and a very small tan δ (dielectric loss tangent). The spacer 9 is inserted between the radome 12 and the printed circuit board 5 to integrate the antenna constituent members, and has a predetermined thickness selected so as to remove the influence of the reflected wave from the inner surface of the radome 12. There is. Reference numeral 13 denotes an outer peripheral rubber ring attached to the fitting portion between the frame 1 and the radome 12,
It is formed to absorb the impact from the side.

The radial waveguide 4 is provided with a power feeding portion for feeding a TEM wave from the center of the frame 1 through the coaxial line 10. This feeding part is the central conductor 1 of the coaxial line 10.
1 is extended to form a top loading probe, which is adapted to be matched with the radial waveguide 4 in a wide band. According to such a configuration, the TEM wave supplied from the coaxial line 10 becomes a cylindrical wave in the radial waveguide 4 and propagates radially from the center to the periphery, and this is picked up by the probe pin 7 and the ring element. It is designed to excite 6.

Next, the structure of the ring element 6 described above will be described with reference to FIG. A probe pin 7 is connected to one end of the ring element 6 to form a feeding point 6a. That is, a through hole is formed in the printed board 5 immediately below the feeding point 6a, and a small circular hole 8 having a radius r1 is also formed in the base plate 2 correspondingly. Then, the diameter r2 (r2 <r2 <
The probe pin 7 of r1) is interposed. In addition, in this figure, in order to make the states of the probe pin 7 and the small circular hole 8 easy to understand, a part of the printed circuit board 5 is omitted.

The probe pin 7 is longer than the substrate thickness L of the printed circuit board 5 and has a pin length C which projects from the base plate 2 and is located in the radial waveguide 4. The pin length C is selected to be an optimum value that does not disturb the transmission wave in the radial waveguide 4 and sufficiently excites the ring element 6 to maximize its radiation efficiency. Further, the ratio (r2 / r1) of the diameter r2 of the probe pin 7 and the radius r1 of the small circular hole 8 is set so as to obtain the optimum characteristic impedance.

According to the above structure, the transmission wave traveling in the radial waveguide 4 is picked up by the probe pin 7, and the feeding point 6a is excited thereby. The ring element 6 emits a circularly polarized wave corresponding to the winding direction of the line because a current is excited along the line formed in a spiral shape.

The ring element 6 is arranged on the printed circuit board 5 in the positional relationship shown in FIG. That is, R
= Φλg / 2π + B (λg: guide wavelength in radial waveguide, B: constant) on the spiral line S, the feeding points 6a of the ring elements 6-1 to 12 are provided, and a straight line from the feeding point 6a is provided. The line 6b extending to the radial waveguide 4
It is arranged so as to match the radius vector passing through the center (feed point). Here, if the radial distance of each element is Sρ and the circumferential distance is Sφ, Sρ = λg, Sφ = 0.8λ
₀ (λ ₀ : spatial wavelength). For example, λ ₀ = 25 mm
At (12 GHz), B = 40 mm, Sρ = λg = 20
mm, Sφ = 20 mm.

By the way, the transmitted wave that travels radially from the center of the radial waveguide 4 toward the periphery is detected by the probe pin 7.
The electromagnetic waves are picked up by electromagnetic coupling by the pin 7, and at this time, the pin 7 reflects a part of the transmitted wave. However, since the probe pins 7 are arranged along the spiral line S, the time at which the reflected wave is generated by the pin 7 gradually becomes slower as the transmission wave moves away from the center.

That is, when viewed from the center O of the radial waveguide 4, the reflected wave generated with the progress of the transmitted wave is always 1
Since the probe pins 7 of the book are generated, the reflected wave does not return from a plurality of pins all at once unlike the conventional case. That is, if the probe pin 7 is positioned in the arrangement relationship shown in FIG. 3, only a reflected wave for one pin is generated, and the reflection loss of the antenna as a whole becomes extremely small. The reflection loss of the radial line ring antenna in which the ring elements 6-1 to 12 are arranged in such a positional relationship is -20 dB.
It has been confirmed that the antenna efficiency is 75%.

The ring element 6 having the above structure can be subjected to a well-known pattern etching process, and the probe pin 7 can also be automatically pinned by an automatic mounting machine. Become.

[0020]

As described above, according to the present invention, the exciting means projecting into the radial waveguide is electromagnetically coupled with the transmission wave traveling in the waveguide, whereby each radiating element is excited. To be done. Here, the reflected wave from each of the protruding excitation means is returned to the center of the radial waveguide with a sequential delay because the excitation means is arranged on a predetermined spiral line defined on the dielectric substrate. . Therefore, since it is substantially affected by the reflected wave of one excitation unit, the reflection loss is extremely small and the antenna efficiency is improved.

[Brief description of drawings]

FIG. 1 is a perspective sectional view showing the overall structure of an embodiment of the present invention.

FIG. 2 is a perspective sectional view showing a partial structure of a radial line ring antenna according to the same embodiment.

FIG. 3 is a plan view showing an arrangement relationship of ring elements 6 in the same embodiment.

[Simple explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Frame, 2 ... Ground plane, 3 ... Low foaming dielectric material, 4 ... Radial waveguide, 5 ... Printed circuit board, 6 ... Ring element, 6a ... Feed point, 6b ... Line, 7 ... Probe pin, S ... Spiral wire.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuji Numano 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (2)

[Claims] 1. A base plate formed on the lower surface of a dielectric substrate,
An upper surface of the dielectric substrate includes a radial waveguide formed of a circular conductor plate serving as an antenna base and arranged to face each other in parallel with the ground plane, and a power feeding unit for supplying electric power into the radial waveguide. A plurality of radiating elements that generate circularly polarized waves, and an exciting means that penetrates the dielectric substrate and projects into the radial waveguide at one end of the radiating element. A radial line ring antenna, which is sequentially arranged on a predetermined spiral line defined on the upper surface of a dielectric substrate. 2. The radiating element has a straight path extending from the starting end and having a predetermined length, and a curved path wound to either the left or the right through the straight path, and the straight path corresponds to the radial waveguide. The radial line ring antenna according to claim 1, wherein the radial line ring antenna is formed on the upper surface of the dielectric substrate so as to face the center direction.