A directional antenna element for use in a phase array with H-plane scanning - Requirements, realisation, nearfields

An element for a phased array with H-plane scanning and a half-power beam-width (HPBW) of approximately 8 deg in the E plane is described. Since scanning is not required in the E plane, the array can be built from as few as 8 single antenna elements. Since backward radiation of the entire array should be negligible, the elements are placed in front of a reflecting plane. A stripline structure ensures that all the radiating parts of the single antenna elements carry currents of approximately equal phase. The structure consists of a polyguide substrate with a printed-on meander-shaped conductor on one side and copper shielding on both sides. The conductor is fed in the center and short-circuited at both ends, thereby causing standing waves along the conductor. To obtain a favorable amplitude distribution of the field strength, the distance between the conductor and the shielding is varied along the antenna.