GB1285289A - An antenna for a strip transmission line - Google Patents

Abstract

1285289 Aerials TELEFONAKTIEBOLAGET L M ERICSSON 21 Oct 1970 [23 Oct 1969] 50046/70 Heading H4A A wideband aerial comprises a portion of strip transmission line with an axially-extending planar inner conductor 1, Fig. 1, and at least one planar outer conductor 11, with intervening dielectric material 4. A plurality of parallel elongate slots of different lengths is provided in an end section of the outer conductor, which cross the inner conductor, and which are not parallel to its axis. Each slot is matched for a particular frequency such that its length is an integral multiple of the corresponding wavelength, and its distance from a corresponding part of the end of the inner conductor is an odd integral multiple of a quarter of this wavelength. The slots may be so closely spaced that they are contiguous and merge into a single slot (Fig. 2a). As described, a second planar outer conductor 6 is spaced from the other side of the inner conductor 1 by dielectric material 3. Near the end 8 of the inner conductor 1, the dielectric material spacers and the outer conductors are extended laterally into two oppositely directed arms. In the space thus provided radiating slots 7a to 7f are made in either or both of the outer conductors, so that they lie across the inner conductor. In other embodiments in which the slots are continguous, so that they merge into a single slot, the ends of said slots are shaped to form a smooth curve, instead of steps (Figs. 2b, 2c, not shown). The lengths of the slots may be arranged to decrease on each side of a central slot, instead of on one side of an end slot (Figs. 3a to 3d, not shown). The end of the inner conductor may be of stepped formation instead of being squared off (Fig. 4, not shown).