Compact Filters and Filter Miniaturization Microstrip filters are themselves already small in size compared with other filters such as waveguide filters. Nevertheless, for some applications where the size reduction is of primary importance, smaller microstrip filters are desirable, even though reducing the size of a filter generally leads to increased dissipation losses in a given material and hence reduced performance. | Microstrip Filters for RF Microwave Applications. Jia-Sheng Hong M. J. Lancaster Copyright 2001 John Wiley Sons Inc. ISBNs 0-471-38877-7 Hardback 0-471-22161-9 Electronic CHAPTER 11 Compact Filters and Filter Miniaturization Microstrip filters are themselves already small in size compared with other filters such as waveguide filters. Nevertheless for some applications where the size reduction is of primary importance smaller microstrip filters are desirable even though reducing the size of a filter generally leads to increased dissipation losses in a given material and hence reduced performance. Miniaturization of microstrip filters may be achieved by using high dielectric constant substrates or lumped elements but very often for specified substrates a change in the geometry of filters is required and therefore numerous new filter configurations become possible. This chapter is intended to describe novel concepts methodologies and designs for compact filters and filter miniaturization. The new types of filters discussed include ladder line filters pseudointerdigital line filters compact open-loop and hairpin resonator filters slow-wave resonator filters miniaturized dual-mode filters multilayer filters lumped-element filters and filters using high dielectric constant substrates. LADDER LINE FILTERS Ladder Microstrip Line In general the size of a microwave filter is proportional to the guided wavelength at which it operates. Since the guided wavelength is proportional to the phase velocity vp reducing vp or obtaining slow-wave propagation can then lead to the size reduction. It is well known that the main mechanism of obtaining a slow-wave propagation is to separate storage the electric and magnetic energy as much as possible in the guided-wave media. Bearing this in mind and examining the conventional microstrip line we can find that the conventional line does not store the electromagnetic energy efficiently as far as its occupied surface area is .
