Adaptive control of radiation patterns for monopole antenna with frequency-selective reflector with loading varactor

An adaptive controllable monopole antenna with a frequency-selective reflector has been developed with a miniature planar structure for MIMO applications. Radiation patterns for the developed antenna could be successfully controlled by a loaded GaAs Shottkey-barrier diode varactor fabricated with a MMIC process. By increasing the capacitance value from 0.23[pF] to 0.43[pF], a measured gain at 2.5[GHz] on the E-plane was controlled to decrease by 2 dB for the direction toward the reflector and to increase by 0.5 dB for the opposite direction.