Design and fabrication of a microstrip low-pass filter with wide stopband and high selectivity

In this paper, a low-pass filter with usage microstrip lines and suitable performance for operation in telecommunication systems is designed, simulated and fabricated. The design of the filter is based on the fifth order chebyshev filter design rules. In order to improve the performance of the low-pass filter parameters, radial suppressor cells and open stubs are used which increase the stopband and narrow transition band (sharp roll-off-rate). The proposed low-pass filter after designed, using simulated ADS software and finally fabricated on the Rogers-RO4003c substrate with a thickness of 0.508 mm (20 mil) and a dielectric constant of 3.38. The -3 dB cutoff frequency for the proposed filter is 1.1 GHz and bandwidth of the stopband is close to 28.5 GHz. The change rate for the filter is appropriate and equal to 79 dB/GHz. The size of filter is relatively small and figure of merit is 26663. The simulation results and the results of the measurement of the fabricated sample are consistent and fairly similar. The proposed filter can be used in telecommunication systems due to good performance.