Design of Microwave Filters With Arbitrary Frequency Response Based on Digital Methods

This letter presents a novel general technique for the design of microwave filters with arbitrary frequency response. It is based on the translation of the microwave specifications to the digital domain, where the well known and readily available digital filter design techniques are applied. By means of these digital techniques, the method provides a straightforward procedure to calculate the poles and zeros corresponding to the analog frequency response that satisfies the target specifications. From the poles and zeros, the microwave filter can be readily obtained using conventional techniques. As an example to demonstrate the proposed technique, a filter with user-defined specifications over two independent passbands has been implemented and successfully tested in microstrip technology.