Design of High Gain Two-Layer Electromagnetically Coupled Patch Antenna in the ISM Band

Microstrip Antennas (MSAs) have several advantages, including that they are light weight and small volume and that they can be made conformal to the host surface. In addition, MSAs are manufactured using printed circuit technology, so that mass production can be achieved at a low cost. In comparison to traditional antenna elements, however, the electrical performance of the basic microstrip antenna suffers from a number of serious drawbacks, e.g. narrow bandwidth; high feed network losses, poor cross polarization, and low power handling capacity. The major disadvantage of the microstrip-patch antenna is its inherently narrow impedance bandwidth of only a couple of percent. Intensive research is going on to develop bandwidth-enhancement techniques by keeping its size as small as possible. Accordingly, increasing the bandwidth of the MSA has been a primary goal of research in the field. We present here a compact two-layer electromagnetically coupled patch antenna with an impedance bandwidth of 35%. The radiation efficiency is obtained 90% in the operating band. The designed antenna is right-hand circularly polarized and operates in the 2.4 GHz ISM-band frequency The proposed structure has been initially optimized using IE3D software followed by experimental verification on Agilent Vector Network Analyzer, E5062A.