A millimeter-wave integrated-circuit antenna based on the Fresnel zone plate

A moderate-gain, easily constructed millimeter-wave integrated-circuit antenna based on the Fresnel zone plate was developed. The gain and bandwidth of the antenna can be varied by adjusting the f/d ratio of the zone plate; this gives the designer some latitude in fitting particular system requirements. The effect of adding the reflector behind the zone plate to increase the gain of the antenna was investigated. It was found that, even without the reflector, the gain of the zone plate was increased because of the 180 degrees phase difference between the reflection off the metal rings and the open rings. As the dielectric constant of the substrate is increased, the performance of the zone plate without the reflector approaches that of the zone plate with the reflector. Thus, on substrates with high permittivity, such as alumina and gallium arsenide, the reflector and lambda /4 spacer may not be necessary.<>