This thesis investigates a new type of microwave tunable filter; the filter is designed based on a new type of resonator called Dielectric Split Ring Resonator (Dielectric-SRR). The new tunable filter is utilised to tune the filter bandwidth at about 2.3 GHz. This bandwidth tuning is achieved by rotating the filter resonators and without adding tuning elements such as screws or varactor diodes. In the measurement the filter resonators are rotated by hand. This thesis also investigates the new Dielectric-SRRs in term of their losses and unloaded quality factor. These new microwave resonators are designed with a configuration similar to the conventional metal Split Ring Resonators (Metal-SRR), but made from dielectric material of high dielectric constant. The new Dielectric-SRR achieved unloaded quality factor \(Q\)\(_u\) 3 times higher than the \(Q\)\(_u\) value of the conventional Metal-SRR. Besides the new tunable filter, a new class of non-tunable filter with two different configurations is investigated. The two filters are designed based on the new Dielectric-SRRs, the first design is 3rd order Chebyshev filter, and the second is a 4th order filter with two symmetric transmission zeros. The non-tunable filters achieved excellent measured performance, and good agreement between measurements and simulations.