Patent ID: 8149180

Claim:
Antenna designed to emit or receive electromagnetic waves at a working frequency f T , this antenna including a first resonator ( 20 ; 60 ; 70 ; 80 ; 90 ; 122 ) formed of: a reflector ( 22 ) reflecting all the electromagnetic waves at frequency f T which are propagated perpendicularly to this reflector, a partly reflecting wall ( 24 ), through which the electromagnetic waves at frequency f T pass, this wall reflecting strictly less than 100% and more than 80% of the electromagnetic waves at frequency f T which are propagated perpendicularly to this wall, a cavity ( 36 ) which is delimited on one side by an upper face of the reflector, and on the other side by a lower face of the partly reflecting wall, and at least one excitation probe ( 38 ; 124 - 128 ) for the cavity, suitable for receiving or injecting into this cavity, at the reflector, electromagnetic fields at frequency f T , characterised in that the first resonator includes a filtering coating ( 40 ) which covers the majority of the upper face of the reflector within the cavity, this coating being suitable for eliminating all electromagnetic waves of frequency f T which are propagated in a parallel direction to the upper face of the reflector, but without eliminating all electromagnetic waves at frequency f T which are propagated in a perpendicular direction to the upper face of the reflector, and in that the filtering coating ( 40 ) forms a PBG (photonic band gap) material which includes at least a first and a second substance, which differ in their permittivity and/or permeability and/or conductivity, and are arranged alternately at regular intervals only along one or more parallel directions to the upper face of the reflector, the regular interval being a function of the wavelength λ 1 of the electromagnetic waves of frequency f T in the first substance, in such a way as to eliminate the electromagnetic waves of frequency f T which are propagated parallel to the upper face of the reflector.