Improving the bandwidth of microstrip patch antennas using resistive loading

Microstrip patch antennas are popular planar antennas due to their low cost, ease of design and manufacture, and low profile. Unfortunately, when fabricated on thin microwave substrates, a microstrip patch exhibits very low bandwidth. Resistive loading has been proposed as a potential technique for improving this bandwidth. This paper analyses the performance of this technique from an efficiency standpoint, showing that efficiency can be very low. An alternative structure is proposed for improving efficiency. This structure allows for a controllable reduction in antenna efficiency in exchange for improved antenna bandwidth.