Fine Control of Filter Performance Based on Composite Right/Left-Handed Metamaterial Technology

Composite right/left-handed (CRLH) metamaterial unit cell whose ground-plane is defected with a rectangular dielectric slot is used to develop a single and multi-pole pole bandpass filter. The unit cell comprises of serially connected interdigital capacitors whose junction is connected to a short-circuited inductive stub. By defecting the ground-plane of the unit cell's structure with a dielectric slot, which is located immediately below the unit cell, enables substantial tuning of the filter's center frequency in the order of 26.5%. This is achieved with minimal effect on the unit cell's insertion and return-loss performance including its selectivity. The filters were fabricated on conventional dielectric substrate and their performance measured to verify the design methodology. The proposed technique eases the trade-off constraints and makes possible the realization of challenging filter specifications constituted from CRLH unit cells using distributed transmission-lines. (c) 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:39-45, 2014.