Improving spurious rejection of ITASAT transponder using Interdigital Microstrip Filter with Quasi-Fractal Koch Curve

This paper shows a quasi-Koch Fractal Shape added into a Interdigital Microstrip Bandpass Filter to improve its spurious rejection without changing the order of filter neither increase its physical dimensions. The Interdigital Filter is first designed based on the SBCD/ITASAT satellite parameters, and then changed to a novel geometry based on the Koch´s Curve Fractal with a relationship of 1:4. Both geometries were simulated and measured, and the numerical results, as well as the simulations, show us that the spurious rejection in the transponder operation became better after the addition of the fractal shape.