Antenna unit having a single antenna element and a periodic structure upper plate

Abstract

An antenna unit consists of an EBG reflector, a single curl antenna supported at a central portion of the EBG reflector, and a periodic structure upper plate disposed apart from a principal surface of the EBG reflector by a predetermined distance. The EBG reflector includes a substrate having the principal surface and (Nx×Ny) square patches which are printed on the principle surface of the substrate and which are arranged in a matrix fashion (lattice structure). The periodic structure upper plate consists of a film and (Nx×Ny) square patch-like conductors printed on the film. The (Nx×Ny) square patch-like conductors are disposed so as to oppose to the (Nx×Ny) square patches, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a conventional antenna unit (a monofilar spiral array antenna);

FIG. 2 is a perspective view showing a curl antenna for use in the antenna unit illustrated in FIG. 1;

FIG. 3 is a view showing of a radiation pattern of the antenna unit illustrated in FIG. 1;

FIG. 4 is a perspective view showing an antenna unit according to an embodiment of this invention;

FIG. 5 is a front view of the antenna unit illustrated in FIG. 4;

FIG. 6 is a view showing a frequency characteristic of a right revolution circularly polarized gain of the antenna unit illustrated in FIG. 4; and

FIG. 7 is a view showing radiation patterns of the antenna unit with a periodic structure upper plate illustrated in FIG. 4 and of an antenna unit without the periodic structure upper plate.

Claims

1. An antenna unit comprising: an EBG (Electromagnetic Band Gap) reflector having a principal surface;a single antenna element supported by said EBG reflector; anda periodic structure upper plate disposed apart from the principal surface of said EBG reflector by a predetermined distance.

2. The antenna unit as claimed in claim 1, wherein said single antenna element is substantially disposed in a center of said EBG reflector.

3. The antenna unit as claimed in claim 1, wherein said single antenna element comprises a curl antenna.

4. The antenna unit as claimed in claim 1, said EBG reflector comprising a substrate having the principal surface and (Nx×Ny) square patches which are printed on the principle surface of said substrate and which are arranged in a matrix fashion, wherein said periodic structure upper plate comprises:a film; and(Nx×Ny) square patch-like conductors printed on said film, said (Nx×Ny) square patch-like conductors being disposed so as to oppose to said (Nx×Ny) square patches, respectively.

5. The antenna unit as claimed in claim 4, wherein said EBG reflector further comprises: a ground plate disposed on a rear surface of said substrate; and(Nx×Ny) conductive-pins for short-circuiting said (Nx×Ny) square patches to said ground plate, respectively.