E-PLANE SCAN PERFORMANCE OF INFINITE ARRAYS OF DIPOLES PRINTED ON PROTRUDING DIELECTRIC SUBSTRATES - COPLANAR FEED LINE AND E-PLANE METALLIC WALL EFFECTS

The effects of coplanar feed lines and of E-plane cavity walls on the performance of infinite arrays of dipoles printed on protruding dielec tric substrates are investigated. In order to do so, two unit cell con figurations are studied: 1) The dipole element fed by coplanar transmi ssion lines and 2) the dipole element fed by coplanar transmission lin es with finite-height metallic walls added parallel to the H plane of the array. The element active impedances are calculated for these conf igurations, and they are compared with those obtained from arrays of d ipoles without coplanar feed lines. Effects of the dielectric substrat e permittivity and of its thickness on the array element active impeda nce are included. The results show that the arrays of dipoles with the coplanar feed lines exhibit feed-line-induced blindnesses which reduc e considerably the scan volume of the array. It is also shown that the se feed line effects are reduced for thicker or higher permittivity su bstrates, and that the insertion of electric walls is one possible ave nue for eliminating these anomalies.