Four Band Stop Defected Microstrip Filters Design and Implementation by Applying a Novel Design Method

Four band stop defected microstrip filters are designed and fabricated. Their design process, simulations and measurement results are presented in this paper. The simulation results and measurement are in a very good agreement. The error of the measurement results from the primary proposed design is less than 0.4%. Defected microstrip filters are widely used as band pass and band reject filters. Their equivalent circuit leads to some zeroes that shapes the transform function. A compact kind of defected microstrip filters are investigated in this paper and are analyzed. The designed band stop filters are designed to reject 750MHz, 1500MHz, 1800MHz and 2600MHz. The proposed process can be applied to design band reject filters for every desired frequency easily. The resonance frequencies reveal themselves as notches occurring in the frequency behavior of the filter. The sensitivity of the rejected frequencies to various parameters is clarified with simulation. The rejected frequencies are related to the most influential parameters affecting them by proposed accurate design formulas. Moreover, in this paper, derived proposed relations are proofed by eight spiral DMFs which are designed based on relations and fabricated with different geometry and fabrication specifications. Measurement results are in a compliance with the values obtained from relations and error is less than 0.38%. The process of design and measurement results reveal that designer can tune the rejected frequency values by simply adjusting the size and geometry based on the parameters achieved by the proposed relations.

Keywords:

band stop filters , notch , filter approximation , microstrip filters