SPIRAL SLOT ANTENNA FED BY COPLANAR WAVEGUIDE USING MAGNETIC PHASE DIFFERENCE

摘要

A new type of spiral slot antennas, using the magnetic flow in the slots for broadband and circular polarizations fed by a coplanar waveguide, is presented in this letter. Two spiral slots are operated as separate radiators. To reduce the magnetic cancellation between the two feeding lines, two spiral slots are fed by sources which are about 180° out-of-phase with each other so that this antenna does not need a balun circuit. The operating frequency range is enlarged by optimizing various parameters. As a result of measurement, the bandwidth of the proposed antenna is 2.7-12 GHz below the return loss of -10 dB, and the 3 dB bandwidth of the axial ratio is in the ranges 4.2-4.7 GHz and 5.9-6.8 GHz.