Broadband Frequency Reconfigurable Antenna Using Capacitive Loading for K-band Applications

A novel reconfigurable antenna in K-band frequency range is presented. The antenna employs a simple capacitive loading technique to increase the -10 dB bandwidth by 2.5 times (+150%). The proposed antenna is designed at the frequency of the unloaded state to operate at 24.2 GHz (bandwidth of 1.8 GHz) and the loaded state at 24.5 GHz (bandwidth of 4 GHz). Antenna gain of 12 dBi and 9 dBi for unloaded and loaded configuration, respectively, are recorded. The directivity of the antenna is optimized by using reflectors and directors. Radiation pattern distortion caused by capacitive loading is corrected by the use of a 14 mm thin dielectric lens. The design frequencies are used in automotive radar. A narrow band centered at 24.2 GHz is used for Adaptive Cruise Control (ACC) and Lane Change Radar (LCR). A broad bandwidth centered at 24.5 GHz is used for Short Range Radars (SRR). The proposed design shows an excellent agreement between the simulated and measured results.