JPH0444404A - Radial line slot antenna - Google Patents

Abstract

PURPOSE:To realize a radial line slot antenna with a broad band and a high gain by devising the circumferential length of a slot to be longer than a circumferential length of a track shaped slot, and making parts of the slots except the middle part wide so as to form an array or barrel shaped antenna. CONSTITUTION:A slot plate 1 is formed to be a metal-made disk and has plural pair slots 2 of almost T-shape formed by the etching processing or the like. Since the slots are overlapped with each other when the width of the slots is increased and its a circumferential length is long, the width of the middle part of the slots is not modified bud other parts are formed wider. Then the the circumferential length of the slots is increased without intersection of the pair slots. When a radio wave radiates from many slots, the coupling coefficient is controlled depending on the length of the slots to make radiation power uniform, thereby establishing the high gain antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radial line slot antenna used in SHF and EI (F bands).

[Conventional technology]

Traditionally, bowl-shaped parabolic antennas have been used in satellite communications and the like, but recently, radial line slot antennas have been proposed in place of the parabolic antennas.

As this radial line slot antenna, for example, there is one shown in Japanese Patent Publication No. 1964-1985. In other words, in a radial waveguide consisting of upper and lower disc-shaped conductors arranged oppositely at equal intervals, the wavelength of the propagation mode that spreads uniformly from the center in the radial direction with the same intensity, which is the most fundamental propagation mode, is λ. , a first point is located on the radial axis of the upper conductor at a distance of δ from the center, and a second point is located on the axis perpendicular to this axis at a distance of δ + 1/4 × λ from the center. a third point on the same axis as the first point and at a distance of δ+l/2Xλ from the center to the opposite side of the first point; δ+3/4×λ on the opposite side,
The fourth point at a distance of .

A fifth point located on the same axis and in the same direction as the first point and at a distance of δ+λ from the center, and on a spiral line sequentially passing through the school of fish determined in the same manner.

A radiating element consisting of a set of slots each arranged on orthogonal lines with a center spacing of 174×λ.

This circularly polarized planar array antenna is characterized in that the slots are sequentially arranged in a substantially curved shape with one side of the slots inclined at about 45 degrees with respect to the radial direction.

[Problem to be solved by the invention]

However, in the above-mentioned conventional antenna, the slot has a track shape with sharp resonance characteristics in order to increase the gain, but such a track-shaped slot has a problem in that the frequency band becomes narrow.

[Means to solve the problem]

The present invention has been made to solve the above problems, and provides a radial line slot antenna in which a waveguide is formed by a slot plate having a large number of slots and a conductor facing the slot plate. This radial line slot antenna is characterized in that its length is longer than the circumference of the track-shaped slot.

Further, in a radial line slot antenna in which a waveguide is formed by a slot plate having a large number of substantially T-shaped paired slots and a conductor facing this slot plate, the slots have a portion other than a central portion thereof. This is a radial line slot antenna characterized by its wide width.

Furthermore, the shape of the slots is an array shape or an hourglass shape.

[Effect]

According to the radial line slot antenna of the present invention, the circumference of the slot is longer than the circumference of a conventional track-shaped slot, thereby making it possible to provide a wide frequency characteristic.

〔Example〕

The present invention will be explained in detail using examples.

FIG. 1 is an explanatory diagram of a radial line slot antenna according to the present invention. In FIG. It has a roughly T-shaped bare slot (2). Also, (3) is a frame.

This frame (3) is made by drawing the peripheral edge of a metal disc, and the slot plate (1) is joined to this peripheral edge.

It is sealed with epoxy resin or the like, and a radial waveguide (4) is formed inside. A power feeding section (5) is attached approximately to the center of the slot plate (1).

Note that a partition plate (not shown) is arranged in the internal space formed by the slot plate (1) and the frame (3).

The radial waveguide (4) may be divided into an upper layer waveguide and a lower layer waveguide, and a folded portion of the waveguide may be formed at the outer periphery of the partition plate.

A radome (6) is attached above the slot plate (1) to prevent rain and the like from entering. This radome (6) is made of slippery Teflon material to prevent lightning from accumulating, and its periphery is covered with a slot plate (1).
and the frame (3) and sealed. Also, the space between this radome (6) and the slot plate (1) (
7) may be laminated with a spacer made of foamed polystyrene or the like, if necessary.

Next, the slot C provided in the slot plate (1)
The shape and arrangement pattern of 2) will be explained.

First, if we make a long and narrow groove in the conductor plate as shown in Figure 2 (B), (C), (Unit), for example, depending on the length of the linear antenna (a゛) It is well known that frequency characteristics are determined.

FIG. 3 is an explanatory diagram for determining the circumferential length of the slot in FIG. 2.

Here, to explain the length of the slot, the relationship between the coupling coefficient, that is, the amount of radiation, and the length of the slot is an upwardly convex paraboloid, as shown in Figure 4, and the slot length is λ,
The radiation amount reaches a peak at /2 (λ is the spatial wavelength). By the way, the antenna has an optimal amount of radiation from the slot, and the slot length to achieve this optimal amount of radiation is located on both sides of λ/2 (a, b). In the case of a pair slot, the design shape The slot length must be set at the small point a. Therefore, the slot length is subject to the above constraints.

To explain specifically, it is known that when the slot is elongated, the slot length resonates around a half wavelength.
In the radial line slot antenna of this embodiment, the slot length is made approximately 25% shorter than the resonance length in order to prevent the radiation amount due to resonance from becoming excessive in some parts due to the presence of a large number of slots. In this way, it is possible to control the strength of the coupling between the inside of the antenna and the external space through one slot, that is, the coupling coefficient indicating the radio wave radiation intensity.

This is to make the radiation power of a large number of slots uniform by gradually radiating the antenna, thereby increasing the gain of the antenna.

However, this alone results in the coupling coefficient being controlled while the resonance characteristic (Q) of the slot remains sharp, that is, the band remains narrow as an antenna, and although the gain is high, the band does not become wide.

Therefore, in order to make Q a wide band, in this embodiment, the shape of the slot is a shape with a longer circumference than the conventional track-shaped slot, as shown in FIGS. Specifically, the shape is rectangular, array-shaped, drum-shaped, etc., and by increasing the circumference, a wide band can be achieved.

By the way, when using a pair of approximately T-shaped slots as in this embodiment, if the width of the slot is increased and the circumference is increased, the slots will collide with each other, so the width of the center portion of the slot must be reduced. It is preferable to leave it as is and make the other parts wider.

By doing so, the circumferential length of the paired slots can be increased without intersecting each other.

Here, a table comparing "slot shape,""slotlength,""slotcircumference," and rQ (resonance characteristic) for the various slots shown in FIGS. 2 and 3 is shown below.

That is, in the antenna of the above-described embodiment, when radio waves are radiated from a large number of slots, the coupling coefficient is controlled by the slot length to make the radiated power uniform and a high-gain antenna is obtained. It is possible to select a slot shape having a Q such that the circumferential length of various slot shapes based on the slot shape is optimal with respect to the target bandwidth.

〔Effect of the invention〕

According to the radial line slot antenna of the present invention, since the circumference of the slot is longer than that of the conventional one, the resonant frequency can be controlled, and a radial line slot antenna with a wide band and high gain can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic explanatory diagram thereof, and FIG. 2 is a portion of the slot plate, in which (a) is a track-shaped slot, (b) is a rectangular slot, and (C) is an array-shaped slot. Slot, (cut is an explanatory diagram of an hourglass-shaped slot, Fig. 3 is an explanatory diagram of slot length and slot circumference, and Fig. 4 is a diagram showing the relationship between slot length and coupling coefficient. (1)...Slot Plate (2)... Pair slot (3)... Frame (4)... Radial waveguide (5)... Power feeding part (6)... Radome (
7)... Spatial Patent Worker Representative of Toppan Printing Co., Ltd. Kazuo Suzuki (Koegip)

Claims (4)

[Claims] (1) In a radial line slot antenna in which a waveguide is formed by a slot plate having a large number of slots and a conductor facing the slot plate, the circumference of the slot is longer than the circumference of the track-shaped slot. A radial line slot antenna characterized by its long length. (2) In a radial line slot antenna in which a waveguide is formed by a slot plate having a large number of substantially T-shaped paired slots and a conductor facing the slot plate, the slots are formed in a portion other than the central portion of the slot plate. A radial line slot antenna characterized by a wide width. (3) The radial line slot antenna according to claim 1 or 2, wherein the slot has an array shape. (4) The radial line slot antenna according to claim 1 or 2, wherein the slot has an hourglass shape.