Multilayer hairpin bandpass filter for digital broadcasting

This paper presents a 2.55-2.61 GHz bandpass filter using hairpin resonators in a multilayer configuration for digital broadcasting application. A combination of four-pole hairpin resonators was designed to operate at center frequency of 2.58 GHz with a bandwidth of 60 MHz. The best return and insertion losses in the passband are -23.753 dB and -2.4955 dB, respectively. The circuit was simulated using Computer Simulation Technology (CST). The Flame Retardant 4 (FR4) substrate with dielectric constant, ε r of 4.6 was used as a material based. The results from the design show that the circuit is working well. Few parameters in the circuit were analyzed and have a good relationship to the microwave theory.