Lakshman Athukorala

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This paper presents a novel filter design technique for the compact microstrip dual-mode filters. An equivalent circuit for the single dual-mode filter section is derived to show that a single unit behaves as a pair of coupled synchronously tuned single-mode resonators. The equivalent circuit was linked to the inverter-coupled bandpass prototype network to(More)
This paper presents an optically reconfigurable microstrip ultra-wideband filter. A single optical switch comprised of a silicon wafer is activated using near infra-red light to select between either a bandpass or bandstop response. With the switch in the ON state, the circuit behaves as a bandpass filter while in the OFF state, the circuit behaves as a(More)
This paper presents a compact highly linear tunable second-order quasi-elliptic filter with constant 3-dB bandwidth. The proposed filter is thoroughly analyzed to clearly describe the filter equivalent circuit and the tuning mechanism involved. In addition, the tunable resonator configuration employed is shown to improve filter linearity, especially for low(More)
A novel compact microstrip dual-mode resonator and filter are proposed. The characteristics of the dual mode resonator are investigated. It is found that the filter response exhibits a desirable stopband response where the first spurious passband naturally occurs at 3f<sub>0</sub>. Finally, methods of miniaturizing such resonators and filters are discussed.(More)
A compact high linearity microstrip dual-mode tunable filter is proposed. The characteristics of the dual-mode tunable resonator are investigated. Methods of minimising the change in bandwidth across the frequency shift are discussed. A tunable filter was demonstrated experimentally to verify the argument where a 35 % shift in the pass-band was observed,(More)
This paper presents two highly compact filter configurations using concentric open-loop resonators. A description of each filter configuration is presented, where a linkage between structural features and coupling coefficients is outlined. A third order trisection and a fourth order source-load coupled filter were designed and fabricated at 1.0 GHz, and(More)
This paper presents an electronically tunable microstrip open loop resonator for RF/Microwave multifunctional systems. Tunability is achieved by using varactor diodes. Simulation results for a filter based on these resonators are demonstrated to have a passband shift of 26%. Experimental results are presented to validate the argument along with theoretical(More)
This paper presents a high linearity reconfigurable ultra-wideband (UWB) filter. The proposed structure is able to achieve high performance with good linearity and no significant loss. A single PIN diode (BAP65&#x2013;02) is used to switch the filter from a bandpass to a bandstop response at the same UWB spectrum. An optical switch, comprised of a silicon(More)
Miniaturised microstrip diplexer and bandpass filters using single ring resonators with good transmission and reflection characteristics on each channel for WiMAX applications have been presented. The size of the proposed diplexer is reduced. The diplexer is easy to manufacture and the results are easily reproducible. The improvement of the performance of(More)
This papers presents the optically switchable microstrip ring resonators for RF/microwave multifunctional systems. Tunability is achieved by increasing the power of the laser applied to the highly resistive silicon wafer and changing the properties of silicon under optical illumination. Tunable ring resonators with and without the optical switches have been(More)