Dual-frequency reconfigurable slot dipole array with a CPW-based feed network using RF MEMS technology for X- and ka-band applications

In recent years there is a growing interest to combine various wireless applications in a single system for miniaturization purposes. A reconfigurable MEMS antenna that can operate in multi- frequencies is an appropriate way of reducing system volume. The monolithic integration of tunable MEMS components with antennas can also reduce parasitic effects, the losses, and packaging costs. Moreover an array of these types of antennas can offer solutions for the systems requiring high antenna gains. This paper presents a 4-element linear array of dual-frequency slot dipole antennas whose resonant frequencies are controlled via MEMS switches placed on the slots. The corporate feed network of the array is realized with coplanar wave transmission (CPW) lines. A CPW-based feed network has advantages over a microstrip feeding network, such as low radiation losses, less dispersion, easier in combining active devices for active array implementation, and the possibility of connecting shunt lumped without the need of via holes through the substrate. The CPW-based feed network in this paper includes properly designed T-junctions, chamfered corners, and dual-frequency impedance transformers in order to match the input impedance at the resonant frequency of the antennas. The proposed array structure, reconfigurable slot dipole antenna, and the details about the dual-frequency impedance transformer are presented in the following sections.