A Dual-Band Bandpass Filter Using SIR Suitable for WiMAX Band
In this paper a dual band bandpass filter with sharp rejection is proposed. The filter is realized by using two half wavelength stepped impedance resonator to operate at the passband 2.5 GHz and 3.5 GHz. To increase the band width further inter-digital capacitors are introduced between resonator and input and output combining network. A finite transmission zero in between two pass band at 2.84 GHz is realized to improve the selectivity of the filter. The design procedure to get highly selective response of the proposed filter is explicitly explained. An equivalent circuit model of proposed filter is developed that matches well with full wave electromagnetic simulations.