Dual-band ring resonator for narrowband application / Nor Fazira Abd Kadir

Microwave filters have important role in many wireless and communication systems such as satellite and cellular mobile network. In such kind of systems, factors such as compact size, low cost, light weight, high performance, and low loss in designing of microwave filters are of primary importance. In comparison with waveguide filters, microstrip filters are smaller and in such applications mentioned before there are needs to have smaller microstrip filters. In this paper, a combination of rectangular-shaped ring resonator with three quarter wavelength coupled lines and a stub is proposed to produce a very narrow dual band filter response. The resonator, which in pairs to a high impedance microstrip line, will generate two operating modes in the desired band. The consequences in varying the length of tuning stubs and gap size between tuning stubs and ring resonator have been studied. Realized on FR4 microstrip substrate, the filter is centred at 2.6GHz and 3.4GHz. The measurement results are found to be equivalent with the simulation.