A novel traveling-wave feed technique for circularly polarized planar microstrip antennas

Many current communication and sensor systems require high-density packing for transceivers. In particular, many such systems require the antenna to be closely integrated with the other transceiver circuitry. In this paper, we propose a new technique, which is capable of yielding high quality circular polarization, with a feeding system that is particularly suitable for incorporating in multi-layer microwave circuits. This type of circuit can be fabricated either in thick-film or LTCC, which are attractive because they can provide a combination of high-performance and low-cost fabrication. The proposed traveling-wave feed system offers a number of advantages over the rear-fed patch techniques. It does not require a probe through the dielectric layer beneath the patch. The current work is an extension of the concept of using a circular slotline channel beneath the dielectric layer to excite four rectangular patch antennas to provide circular polarization. In order to establish the validity of the proposed technique, a prototype 5 GHz antenna with a progressive incremental offset of 500 μm was designed and tested.