Anil Kamma

A compact spurious free, quad‐band, band‐pass filter (BPF) having independently controllable and widely spaced frequency bands is proposed. The design consists of a basic BPF to which the authors introduce transmission zeros (TZs) in the frequency response using T‐shaped stubs loaded with a modified ring resonator (MRR) thereby creating the four passbands. This design results in very high band‐to‐band isolation. The TZs are obtained by transversal signal path cancellation and also due to the loaded T‐shaped stubs. The BPF consists of a stepped impedance low‐pass filter which provides spurious free out of band characteristics up to 20GHz. By changing the tapping position of the MRR, the frequencies of the TZs can be adjusted to get the desired pass band characteristics. The proposed quad‐band filter provides low‐insertion loss (<1dB) at the four passbands centred at 2.4, 5.1, 7.7 and 10.1GHz. The simulation results of the filter are verified experimentally.

A novel, compact, multiple band notch filter and dual-band filters are presented. Contiguous and concentric split ring resonators (SRRs) and Ring resonator are used to achieve desired multiple narrow band notches. These band notches have been designed to avoid the undesired interference between co-existing wireless channels. The dual-band filter consists of a dual SRR having splits on the opposite sides with Inductive Short Stub Split Ring Resonator. Even- and odd-mode analyses have been performed to calculate the resonance frequencies. Three transmission zeros are achieved between the two passbands by both dominant electric or dominant magnetic coupling and also cancellation effect of electric and magnetic coupling. This results in high passband selectivity and improved band-to-band isolation. The proposed dual-band pass filter has the advantages of being compact with more degree of freedom to achieve desired passbands by controlling the electric and magnetic coupling independently. Proposed filter is implemented on RT/Duroid 5880 (ε_r = 2.2) substrate of thickness 0.785 mm and surface area of 0.27λ_g × 0.27λ_g. Insertion loss of the proposed filter at notch bands is high (>13 dB) and low (<0.8 dB) in pass band. Measured results correlate with the simulated results and thus ensure that the proposed filter is a suitable candidate to mitigate interference caused by the co-existing and emerging wireless technologies.