A new class of wide-band microstrip arrays

Wide-band microstrip antennas are still a challenge and in the last couple of years a number of new configurations have been reported. Most of these configurations are multilayer patch antennas with some of them achieving up to 40% in bandwidth. Recently, another new geometry has been reported, a single patch fed by a three-dimensional feed line, which in essence is a very tall patch fed by a wide-band dipole. This antenna is reported to exhibit a 90-100% bandwidth for VSWR <2:1; towards the high end of the band, however, the radiation from the wide-band dipole is too strong and interferes with the patch pattern resulting in a high crosspolarization level. In the array environment, though, the crosspolarization is reduced by the array factor. The paper analyzes the performance of an eight-element array and its scanning capabilities. To avoid grading lobes the radiating elements have to be very close to each other, so the impact of the mutual coupling is also investigated