RC-loaded planar half-ellipse antenna for impulse radar application

Combined with the resistor loading and capacitive loading technique, a planar printed ellipse antenna is designed to achieve ultra-bandwidth and upper radiation efficiency. To accomplish loading, four resistor lumps bridge the metallic strip against the antenna arm on the top layer and rectangular conducting cavity. Simulations are performed for various characteristics of the antenna such as current distribution, near-field radiation pattern and time waveform. Comparison of antenna characteristics between the antenna with resistor loading (type-I) and the antenna with resistor and capacitive loading (type-II) is made using simulations and measurements. The proposed antenna is constructed and measured. It is shown that the antenna achieves an ultra-bandwidth over 8:1 (1-8 GHz) with a return loss less than -10 dB. In addition, experimental verification has been carried out to confirm the improved properties of the antenna. The capacitive loading produced at the end of the antenna arm has improved the peak of the radiation waveform at least 0.62 dB without the cost of increased size.