Novel Dual-Mode Microstrip Triangular Patch Resonator Bandpass Filter

Some new characteristics of microstrip equilateral triangular patch resonator with fractal defection are analyzed, and novel fractal bandpass filters using equilateral triangular resonator are presented to implement high performances of multi-transmission zeros, wide passband and stopband, and low passband insertion loss as well as miniaturization. Due to the space-filling property of fractal geometry, this structure can adjust the location of the transmission zero, it also effectively control the filter's size. The proposed filters have compact and simple structures, small sizes, high selectivity and so on, and all these features are the requirement of wireless communication circuits. By adjusting filters parameter, we get the optimized S-parameters. The resonant frequency shifts to lower frequency locations by increasing hemline length c. Measured results of the filter using three fractal-shaped structures are in good agreement with the simulated ones.