Microstrip-line-fed compact microstrip antenna with broadband operation

In order to meet the requirement for mobile or personal communication systems, microstrip antennas with reduced size and broadband operation are of particular interest. Among the various feeding mechanisms, the compact broadband microstrip antennas directly matched to a 50-/spl Omega/ microstrip line are also of importance, for its usefulness in integration with microwave integrated circuits. For this purpose, we present in this article several related designs of microstrip antennas to broaden the operating bandwidth and reduce the overall size of the antenna. These compact broadband designs are achieved using a chip-resistor loading, which effectively lowers the resonant frequency of the microstrip antenna, improves the antenna bandwidth, and eases the stringent tolerance of the impedance matching problem. In this study, details of the antenna designs using chip-resistor loading are described. Experimental results of the designs with rectangular, circular, and triangular microstrip patches are presented and discussed.