A New Class of Microwave Dual-Band Filter Based on Hybrid Chebyshev Polynomials

This paper introduces a new class of dual-band microwave filter using hybrid Chebyshev polynomial functions. It may be shown that the Chebyshev function of its first and second kind can be used to form a hybrid filtering function in which a novel transfer function of a dual-band low pass prototype (DBLPP) is defined. In contrast to recent filter topologies and design techniques with specific transformations, the proposed DBLPP network allows classical ladder synthesis and frequency transformation for the construction of dual-band bandpass filter. A prototype based on interdigital structure was designed and simulated which shows excellent agreement with the theory. A symmetrical dual-band response with 50MHz bandwidth, passband return loss of 15dB and a notch at center frequency of 0.98 GHz is obtained.