Spiral Microstrip Bandpass Filters

Abstract

Microstrip bandpass filters based on spiral resonators are designed at 700MHz for 5G applications. In order to achieve size reduction, spiral resonators are used. The proposed filters are of third and fifth orders. The filters are printed on FR4 substrate with thickness of 1.6mm and dielectric constant of 4.5. The filters are simulated using CST electromagnetic simulator. The simulated results show that the presented filters exhibit good return losses, low insertion losses within the passband. Furthermore, a good selectivity is obtained. The simulated reflection coefficients are -15 dB and -12 dB for the 3rd and 5th order filters respectively. The fifth order bandpass filter provides higher selectivity but higher insertion loss as expected.