Microstrip antenna array for mobile communications

Several challenges remain in the development of antenna arrays for mobile communications and one of these is the availability of efficient radiating elements interfacing with the beamformer. This paper presents a development effort for a novel printed array antenna. We present a modified version of such antennas by adding a series capacitance to the patch equivalent circuit, implemented by electromagnetic coupling, and varying the distance between the successive elements in a non linear way. It was found through experiments that the bandwidth of such antennas is increased to 1.5 GHz. The comparison of the theoretical results and the measured values shows a good agreement. The design and realization of this log-periodic array at 30 GHz, are implemented on a high dielectric constant substrate (ε_r=9.9), which is close to the dielectric constant of GaAs. The feasibility of integration of such an antenna structure into a monolithic circuit is demonstrated