Compact dual-band bandpass patch filter using coplanar waveguide feed method

By employing the coplanar waveguide feeding method, a dual-band dual-mode bandpass patch filter, with flexible frequency ratio and fractional bandwidth, is proposed. Two resonant frequency bands are achieved by using two stacked square patches with different cross slots etched, which are simultaneously excited by the centre CPW fed lines. The frequency ratio and fractional bandwidths can be controlled by the CPW broadside coupling and cross slots. To verify the proposed configuration, two dual-band bandpass patch filters have been designed, fabricated and measured. © 2012 The Institution of Engineering and Technology.