JPH034129B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a microstripline antenna, and particularly to a structure for improving antenna characteristics and weather resistance.

<Prior Art> Conventionally, there is a microstrip antenna as disclosed in Japanese Patent Laid-Open No. 59-207703. As shown in FIG. 4, a ground conductor plate 2 is formed on the back surface of a first dielectric plate 1, a circular radiating conductive element 3 is formed on the front surface, and the radiating conductive element 3
A second dielectric plate 4 is placed a predetermined distance away from the
A parasitic element 5 made of a conductive plate having approximately the same shape as the radiating conductive element 3 is provided on the back side of the parasitic element 5, and a third dielectric element 5 is provided between the first and second dielectric plates 1 and 4. A body 6 is inserted therein.

<Problems to be solved by the invention> In such a microstrip antenna,
Since the radiation conductive element 3 and the parasitic element 5 are covered with the third dielectric 6, these elements 3,
5 can be prevented from being oxidized by ultraviolet rays, rain, snow, etc., but there is a problem that loss occurs when radio waves pass through the third dielectric 6, resulting in a decrease in gain and deterioration of antenna characteristics. .

<Means for solving the problem> A means for solving the above problem includes a first dielectric plate provided with a ground conductor on one surface. On the other surface of the first dielectric plate, at least one row of periodically bent first stripline conductors is provided as a radiating element.
Above this first stripline conductor, a second
The dielectric plate is approximately 1/1/2 of the center frequency of the frequency band used.
They are placed at a distance of 4 wavelengths. A second stripline conductor having a similar shape with slightly longer width and length than the first stripline conductor is provided on the lower surface of the second dielectric plate as a parasitic element with both ends open. There is. The second stripline conductor is disposed substantially opposite the first stripline conductor.

<Example> This example has a rectangular dielectric plate 10 as shown in FIG. A metal foil is provided as a ground conductor 12 over the entire lower surface of this dielectric plate 10 . As the dielectric plate 10, Teflon (registered trademark), crosslinked polyethylene, or the like can be used.

A stripline element 14 is provided on the surface of the dielectric plate 10 along its length.
As shown in an enlarged view in FIG. 3, this stripline element 14 is composed of a plurality of elements bent in an approximately inverted Ω-shape arranged in series in one row. The dimensions a, b, c, and w of each element of this stripline element 14 are determined depending on the center frequency of the frequency band used and the predetermined polarization, for example, 12G.
For linear polarization in Hz, a=λ _g /4, b=λ _g /2,
c = λ _g /4, W = 2 mm, in the case of 12 GHz circular polarization,
a=λ _g /2, b=λ _g /2, c=λ _g /4, W=2mm
(where λ _g is the line wavelength), and the number of them to be connected in series is appropriately selected depending on the antenna gain to be obtained. Although not shown in the figure, one end of this stripline element 14 is grounded via a dummy resistor, and the other end is used as a power feeding end.
Therefore, this stripline element 14 functions as a radiating element.

Above the dielectric plate 10, there is another dielectric plate 1 at a predetermined interval h, for example, about 1/4 wavelength of the center frequency.
6 is placed. 18 is a spacer for maintaining the distance between the dielectric plates 10 and 16. The dielectric plate 16 can be made of the same material as the dielectric plate 10, but epoxy resin can also be used.

A stripline element 20 is also provided on the back surface of the dielectric plate 16. This means that the dimensions of each part of the stripline element 14 are the dimensions a, b,
They are each formed somewhat larger, for example, 5%, than c and w, and the number of elements in series is the same as the number of stripline elements 14. The position of this stripline element 20 is selected so that it faces the stripline element 14. Both ends of this stripline element 20 are open,
It is considered a parasitic element.

In FIG. 5, the antenna gain-frequency characteristics of this microstripline antenna are shown by a solid line. However, the stripline elements 14, 20
The number of series elements in both is nine. In addition, the antenna gain when the dielectric plate 16, spacer 18, and stripline element 20 are removed is indicated by dotted lines in the figure.
Indicates frequency characteristics. As can be seen from this, in this microstripline antenna, the antenna gain at the center frequency f ₀ (GHz) is
Compared to the one in which 0 is removed, ΔG is improved, and the frequency bandwidth (down 3 db) is also improved by expanding to ΔF'<ΔF.

In the above embodiment, the stripline element 1
Although only one row is provided for 4 and 20, a plurality of rows may be provided for each.

<Effects> As described above, according to the present invention, it is possible not only to improve the antenna gain but also to widen the frequency bandwidth. Moreover, the second dielectric plate 1
6 prevents ultraviolet rays, rain, and snow from directly hitting the first dielectric plate 10, thereby preventing the first microstripline element 14 from being oxidized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of a microstripline antenna according to the present invention, FIG. 2 is a front view of the same embodiment, and FIG. 3 is an enlarged plan view of a stripline element used in the same embodiment. Figure 4 is a perspective view of a conventional microstrip line antenna;
The figure is an antenna gain-frequency characteristic diagram of the same embodiment and that of this embodiment in which the spacer, the second dielectric substrate, and the second microstripline element are removed. 10...First dielectric plate, 12...Ground conductor, 1
4...First stripline element, 16... Second stripline element.

Claims (1)

[Claims] 1 A ground conductor is provided on one side of the first dielectric plate,
A first stripline conductor having a periodically bent shape is provided as a radiating element in at least one row on the other surface, and a second dielectric plate is placed above the first stripline conductor at the center of the frequency band used. A second strip line conductor is provided at a distance of about 1/4 wavelength of the frequency and has a similar shape slightly longer in width and length than the first strip line conductor on the lower surface of the second dielectric plate. A microstripline antenna in which a stripline conductor is provided as a parasitic element with both ends open in a state substantially facing a first stripline conductor.