UWB Antenna Design Based on Gain Optimization

In the present paper an ultra-wide band antenna in frequency range of 300-3000 MHz is designed and optimized. The main approach adopted here is the optimization of UWB antenna based on: good impedance matching in frequency range of 300-3000 MHz and good gain flatness in frequency range of 900-2200 MHz for antenna boresigth and neighbor angles. Main reason of gain flatness requirement in these frequency is that this restrict is guaranteed the pulse handling of antenna, without pulse distort in these frequency range that the main power of our pulse generator is in these frequency range. The analysis of antenna is done through finite difference time domain method with simulation at CST Microwave studio and the optimization of antenna is done with direct search gradient method. Physically the antenna resembles a V shape with symmetric arms whose parts slope is different. After analyzing of antenna in each step, with applying gradient optimization method, the slope of each part of antenna arms is calculated. The optimization is based on variation of slope of antenna arm so provided for us the good impedance matching in frequency range of 300-3000 MHz and good gain flatness if frequency ranges of 900-2200 MHz Also in connection of antenna input to the pulse generator we use the balun that fabricated from coax cable, for good feeding of balanced input of antenna from unbalance output of coax cable.