Compact inline substrate integrated waveguide filter with transmission zeros

Abstract

Quick evolution of modern telecommunication technologies poses new challenging problems for designers of high-performance, compact, low-cost and easy-to-manufacture microwave filters. New planar structures – substrate integrated waveguides (SIW), viable to meet the present requirements were proposed in the past decade [1] and replaced conventional rectangular waveguides which are expensive, difficult to fabricate and integrate. Elliptic and pseudo-elliptic filters have lately found wide application in microwave and mm-wave systems owing to their sharp slopes and ability to produce transmission zeros at predicted frequencies. Singlets have been introduced in [2] as the simplest element for modular filter synthesis, which helps to reduce sensitivity of this type of filters to the manufacturing tolerances [3]. Inline pseudo-elliptic bandpass filter based on singlets has been successfully designed in [4] using conventional waveguide technology.