Patent ID: 7233299

Claim:
A system for transmitting and/or receiving electromagnetic waves comprising: a device for focusing the electromagnetic waves transmitted and/or received by the system on a focal point, and a transmitter and/or receiver of electromagnetic waves placed roughly at the focal point so as to transmit and/or receive said electromagnetic waves, wherein it comprises a multiple-beam antenna, the outer radiating surface of which is placed roughly on the focal point so as to form said transmitter and/or receiver of electromagnetic waves, the antenna comprises: a photonic bandgap material designed to filter the electromagnetic waves spacewise and frequencywise, this photonic bandgap material having at least one bandgap and forming an outer surface radiating in transmit and/or receive mode, at least one periodicity defect of the photonic bandgap material so as to produce at least one narrow bandwidth within said at least one bandgap of this photonic bandgap material, and an excitation device for transmitting and/or receiving electromagnetic waves within said at least one narrow bandwidth produced by said at least one defect, this excitation device being designed to work simultaneously at least about a first and a second separate working frequencies, the excitation device includes a first and a second excitation elements, separate from and independent of each other, each designed to transmit and/or receive electromagnetic waves, the first excitation element being designed to work at the first working frequency and the second excitation element being designed to work at the second working frequency, the or each periodicity defect of the photonic bandgap material forms a leaky resonating cavity presenting a constant height in a direction perpendicular to said radiating outer surface, and predefined lateral dimensions parallel to said radiating outer surface, the first and the second working frequencies are designed to excite the same resonance mode of a leaky resonant cavity, this resonance mode being established identically regardless of the lateral dimensions of the cavity, so as to create on said outer surface respectively a first and a second radiating spots, each of these radiating spots representing the origin of a beam of electromagnetic waves radiated in transmit and/or receive mode by the antenna, each of the radiating spots has a geometric center, the position of which depends on the position of the excitation element producing it and the area of which is greater than that of the radiating element producing it, and the first and the second excitation elements are placed relative to each other such that the first and the second radiating spots are positioned on the outer surface of the photonic bandgap material alongside each other and partially overlap.