Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
93 words
A planar antenna comprising a planar assembly (20,28) and a back structure (22), the planar assembly comprising parallel first and second layers, the first layer (20) having an array of resonant slots (21) and the second layer (28) having a network of feed conductors associated with said slots (21), the antenna being characterised by the back structure (22) comprising a conductive sheet having a plurality of discrete projections (23) extending towards inter-slot regions (26) of said first layer (20), said back structure (22) providing a resonant cavity for each of said slots (21).
Claim 2
Dependent Claim
93 words
A planar antenna comprising a planar assembly (20,28) and a back structure (22), the planar assembly comprising parallel first and second layers, the first layer (20) having an array of resonant slots (21) and the second layer (28) having a network of feed conductors associated with said slots (21), the antenna being characterised by the back structure (22) comprising a conductive sheet having a plurality of discrete projections (23) extending towards inter-slot regions (26) of said first layer (20), said back structure (22) providing a resonant cavity for each of said slots (21).
Claim 3
Dependent Claim
25 words
A planar antenna according to Claim 1, wherein said back structure (22) comprises a metal sheet in which said projections (23) are formed by pressing.
Claim 4
Dependent Claim
39 words
A planar antenna according to Claim 1 or Claim 2, wherein said projections (23) are secured to said first layer (20) at said inter-slot regions (26), the height of said projections (23) determining the depth of said resonant cavity.
Claim 5
Dependent Claim
44 words
A planar antenna acccording to any preceding claim, wherein said projections (23) have such size and shape and such position, relative to said slots (21), that they do not extend within the boundaries of said slots as projected on to said conductive sheet (22).
Claim 6
Dependent Claim
14 words
A planar antenna according to Claim 4, wherein said resonant slots (21) are circular.
Claim 7
Dependent Claim
67 words
A planar antenna according to Claim 5, wherein said first layer comprises a rectangular array of slots in equally spaced rows and columns, the maximum dimension of each said projection, measured in a plane parallel to that of said conductive sheet, being less than (1.41 a - b ), where a is the distance between adjacent rows or columns and b is the diameter of each slot.
Claim 8
Dependent Claim
15 words
A planar antenna according to any preceding claim, wherein said projections (23) have circular cross-section.
Claim 9
Dependent Claim
42 words
A planar antenna according to any preceding claim, wherein for any given slot, projections in the vicinity of that slot serve to reduce the number of degenerate modes of operation in the section of said resonant cavity associated with said given slot.
Claim 10
Dependent Claim
65 words
A planar antenna according to any preceding claim, wherein said planar assembly comprises a third layer (27) having an array of resonant slots (21) corresponding to and aligned with the slots (21) in said first layer (20), said second layer (28) being disposed between said first and third layers (20,27) so that each said feed conductor is associated with a pair of corresponding slots (21).
Claim 11
Dependent Claim
30 words
A planar antenna according to Claim 9, wherein said first, second and third layers (20,28,27) are mutually spaced by air, said second layer (28) providing a suspended stripline feed network.
Claim 12
Dependent Claim
31 words
A planar antenna according to Claim 9, further comprising two layers of dielectric material (33,34) respectively disposed between said first and second layers (20,28) and said second and third layers (28,27).
Claim 13
Dependent Claim
24 words
A planar antenna according to any preceding claim, wherein portions of said feed conductors comprise probes (15) adapted to couple energy with said slots.