Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
148 words
An antenna operative at a first nominal frequency, for mounting in front of a second antenna operative at a second nominal frequency and being substantially transparent at the second nominal frequency, characterised by a transmission line sandwich structure with a ground plane (14, 22, 31 or 44), at least one dielectric layer (12) and a second conductive plane (10) consisting of one or more conductive areas shaped to define an array of flat plate radiators (13 or 43) or slot radiators (37) dimensioned in accordance with the first nominal frequency, a feed network (16, 23, 36 or 41) for the radiators such that they collectively provide a directional radiation pattern at the first nominal frequency, and at least the said conductive area(s) being formed of a conductive grid which appears as a continuous conductor at the first nominal frequency but is substantially transparent at the second nominal frequency.
Claim 2
Dependent Claim
148 words
An antenna operative at a first nominal frequency, for mounting in front of a second antenna operative at a second nominal frequency and being substantially transparent at the second nominal frequency, characterised by a transmission line sandwich structure with a ground plane (14, 22, 31 or 44), at least one dielectric layer (12) and a second conductive plane (10) consisting of one or more conductive areas shaped to define an array of flat plate radiators (13 or 43) or slot radiators (37) dimensioned in accordance with the first nominal frequency, a feed network (16, 23, 36 or 41) for the radiators such that they collectively provide a directional radiation pattern at the first nominal frequency, and at least the said conductive area(s) being formed of a conductive grid which appears as a continuous conductor at the first nominal frequency but is substantially transparent at the second nominal frequency.
Claim 3
Dependent Claim
22 words
An antenna according to claim 1, characterised in that the transmission line sandwich structure is a microstrip structure (13, 23, 12, 22).
Claim 4
Dependent Claim
23 words
An antenna according to claim 1, characterised in that the transmission line sandwich structure is a slotline structure (34, 35, 36, 37, 31).
Claim 5
Dependent Claim
20 words
An antenna according to claim 1, wherein the transmission line sandwich structure is a coplanar stripline structure (42, 43, 44).
Claim 6
Dependent Claim
20 words
An antenna according to claim 3 or 4, characterised in that slot widths equal an integral number of grid pitches.
Claim 7
Dependent Claim
34 words
An antenna according to any of claims 1 to 5, characterised in that the antenna is disposed on a conductive surface (14, 22) of a primary antenna, which surface constitutes the said ground plane.
Claim 8
Dependent Claim
44 words
An antenna according to any of claims 1 to 5, characterised in that the ground plane is also a conductive grid (31 or 44) which appears as a continuous conductor at the first nominal frequency but is substantially transparent at the second nominal frequency.
Claim 9
Dependent Claim
31 words
An antenna according to any of claims 1 to 7, characterised in that the transmission line sandwich structure also incorporates the feed network leading to the flat plate or slot radiators.
Claim 10
Dependent Claim
29 words
An antenna according to any of claims 1 to 5, 7 and 8, characterised in that the antenna is a self-contained structure mountable in front of a primary antenna.