GB997773A - Slotted waveguide antenna - Google Patents

Abstract

997,773. Aerials. HUGHES AIRCRAFT CO. June 21, 1963 [Aug. 22, 1962], No. 24792/63. Heading H4A. [Also in Division H1] An aerial array is formed of two groups of slots 42, 48, Fig. 2, in a broad wall 25 of a rectangular waveguide 24 and the groups radiate in respectively different frequencybands by reason of the groups of slots coupling to two differ ent modes propagated through the waveguide. In one embodiment the TE 10 and TE 30 modes are propagated through the waveguide 24 and for the TE 3o mode the waveguide may be thought of as three adjacent " waveguides " 24a-24c each supporting the TE 10 mode at the higher frequency and each having common " virtual walls " 52, 54. A group of shunt slots 42 resonant at the higher frequency are disposed along the waveguide at odd multiples of the higher frequency quarter wavelength and spaced on alternate sides of the centre lines 36, 38, 40 of the " waveguides " 24a- 24c, so that the slots radiate in phase. A second group of slots 48 is coupled to the TE 10 mode by posts 50, Fig. 5, the slots 48 being located along the centre line of the waveguide and the posts 50 being positioned in the planes of the " virtual walls " 52, 54, to avoid coupling to the TE 30 mode. The TE 3o mode is coupled from a waveguide 72 into one end of the waveguide 24 by slots 66, Fig. 4, resonant at the higher frequency. A slot 78 resonant at the lower frequency and situated on the centre line 38 of the waveguide 24 serves, together with a probe 76 positioned in the plane 54 of the " virtual wall " or mode of the TE 3o mode, to propagate the TE 10 mode. The other end of the waveguide 24 may be closed by a plate or a matched load and in other embodiments other arrangements of slots are described with reference to Figs. 6-10 (not shown), some embodying dielectric loaded slots.