Miniaturized RF/microwave filters using fractals

The analysis and design of miniaturized fractal filters is presented in this paper. It is shown that fractal resonators can be significantly smaller than conventional planar resonators for the same resonant frequency requirements. It is seen that when increasing the number of fractal iterations, the size of the resonators decreases and the quality factor increases. The filter design method is based on the synthesis of an inline prototype with symmetrical or asymmetrical pseudo-elliptic characteristics and coupling factor simulations using a commercial electromagnetic simulator. The fractal filters were designed using suspended substrate technology and fabricated in house and with the services of a regular PCB company.