An antenna includes a ground layer, two polarization signal feeding terminals disposed on the ground layer, two polarization structures, four coupling metals and four radiating metals. The first polarization structure includes a first extending portion electrically connected to the first polarization signal feeding terminal and extends from a first channel to a second channel in a first direction over the ground layer. The second polarization structure includes a second extending portion electrically connected to the second polarization signal feeding terminal and extends from a third channel to a fourth channel in second direction over the ground layer, wherein the first extending portion crosses the second extending portion in a non-contact manner to define four regions. The four coupling metals are disposed on the first through the fourth regions, respectively. The four radiating metals are disposed on the first through the fourth channels, respectively.

This antenna device comprises an antenna element disposed in a recess 2 on the exterior of a moving body, and a non-feeding element of which the center is disposed at a position higher than the horizontal plane in which the center of the antenna element is positioned in the recess. In the antenna device, furthermore, the moving body is a vehicle, and the recess may be provided in a roof 1 of the vehicle.

This antenna device comprises an antenna element disposed in a recess 2 on the exterior of a moving body, and a non-feeding element of which the center is disposed at a position higher than the horizontal plane in which the center of the antenna element is positioned in the recess. In the antenna device, furthermore, the moving body is a vehicle, and the recess may be provided in a roof 1 of the vehicle.

According to an aspect, there is provided a passive antenna module for an active-passive antenna system. The passive antenna module includes a chassis for detachably mounting onto an active antenna module. The chassis includes an opening or a cavity for extending at least partially over the active antenna module when the chassis is mounted onto the active antenna module. The passive antenna module includes a ground plane layer arranged within or over said opening or cavity and fixed to the chassis. The ground plane layer includes a metallic or metallized grid. The passive antenna module includes a first antenna array including one or more first antenna elements arranged, in part, over said chassis and adjacent to said opening or cavity and, in part, over said opening or cavity. The chassis and the ground plane layer are adapted to act as ground planes for the first antenna array.

Provided herein are various enhanced arrangements for arrays of aperture antennas, such as horn antennas or short backfire antennas. Examples include an array of aperture antennas having a wall thickness between apertures, and a conductive mesh positioned above the apertures such that openings of the conductive mesh are aligned with the apertures and positioned having a selected spacing between the conductive mesh and the apertures.

An antenna device and a wireless communication apparatus capable of improving performance are provided. The antenna device includes a first antenna element and a second antenna element disposed on the side of one surface of the first antenna element. The first antenna element includes a first glass substrate and a first patch antenna provided on the first glass substrate. The second antenna element includes a second glass substrate and a second patch antenna provided on the second glass substrate. The shape of at least one of the first patch antenna and the second patch antenna in a plan view is a rectangle. Contours of one or more of four corners of the rectangle include a curved line or a plurality of obtuse angles in a plan view.

An antenna device and a wireless communication apparatus capable of improving performance are provided. The antenna device includes a first antenna element and a second antenna element disposed on the side of one surface of the first antenna element. The first antenna element includes a first glass substrate and a first patch antenna provided on the first glass substrate. The second antenna element includes a second glass substrate and a second patch antenna provided on the second glass substrate. The shape of at least one of the first patch antenna and the second patch antenna in a plan view is a rectangle. Contours of one or more of four corners of the rectangle include a curved line or a plurality of obtuse angles in a plan view.

An array antenna (A) in a medium (M) comprises a plurality of radiating elements (ER.sub.T) ensuring the transition between the antenna and the medium, the reflectivity of each element depending on a parameter, the reflectivity of a first element being close to that of the medium, the reflectivity of a last element being close to that of the antenna, the reflectivity parameter of the elements varying from one element to the next. A method comprises calculation of a path equal to the sum of the variations of the reflectivity from one element to the next element, optimization of the variation of the reflectivity parameter so that equivalent radar cross-section of the antenna is the lowest possible or the antenna best observes the radiation objectives, determination of the different elements as a function of said parameter, and simulation of the overall reflectivity and/or of the radiation of the antenna.

An antenna device includes a substrate having a base material containing a dielectric and a conductor, a waveguide, an antenna, and a matching portion arranged in the base material as a part of the conductor. The antenna faces the upper wall portion, and has a plurality of patch portions arranged in an array, a plurality of feeding lines extending in a direction from the patch portion and individually provided for the patch portions, and a plurality of short-circuit portions individually provided for the patch portions and electrically connecting the patch portion and the upper wall portion. The upper wall portion has a plurality of openings 34 individually formed with respect to the feeding lines. Each of the feeding lines extends into the waveguide through the corresponding opening.

An antenna apparatus is provided. The antenna apparatus includes a cavity element, a radiating element, and a feeding element. The cavity element includes an opening. The radiating element is located in the opening and is disposed at a conductive layer. An outline of the radiating element and the opening form a surround slot. An imaginary rectangle has four sides respectively abutted against an external outline of the surround slot. The feeding element is disposed at another parallel conductive layer. The feeding element includes two sections. There is a coupling spacing is between a section and the radiating element to feed into the radiating element through electric field coupling. A tail end of the section is an open circuit. Another section is an initial section of the feeding element inserted into the opening. There is a shifting spacing between the another section and a central line of the imaginary rectangle.