A narrowband bandpass filter with high rejection in the stopband and good passband performance is presented in this paper. This filter consists of three front-coupled sections that are connected in series form. The LC equivalent circuits of the resonators are derived to evaluate the behavior of different parts of the filter. The electromagnetic (EM) and circuit simulations are performed and their agreement verifies the validity of the LC model. The proposed filter has a center frequency of 5 GHz that is compatible with IEEE 802.11a standard with 18 MHz bandwidth. The harmonics are suppressed in the range of DC to 4.46 GHz and 5.5 GHZ to 14.44 GHz with attenuation higher than 31 dB. The filter has been designed, fabricated and measured and the measurement results are in good agreement with the EM-simulation.
