Low Pass Filter with Wide Rejection Band in Microstrip Technology

In this paper, a new technique to design low pass filters in microstrip technology is proposed. The technique is based on the use of the transverse microstrip resonant mode and it is an excellent tool for the design of filters with stringent requirements like sharp cutoff frequency response and wide rejection bandwidth. Due to the fact that these features are not easily achieved with conventional methods, it is a very promising technique. As an example, a design with a cutoff frequency of 2 GHz and a rejection band up to 15 GHz is shown. As it will be seen, the steep slope achieved in the example is equivalent to that obtained with a classical 29^th -order Chebyshev low pass filter.