Compact balanced dual-band bandpass filter with magnetically coupled embedded resonators

Abstract

A compact, balanced, dual-band bandpass filter with flexible and independent control of the differential-mode response is presented in this study. The filtering mechanism relies on the use of magnetically coupled embedded resonators. This provides two clear advantages: high level of miniaturisation and two differential-mode passbands that can be independently tuned. The response of the differential-mode is controlled by the external quality factor and coupling coefficients, whereas the common-mode is inherently rejected thanks to the use of a magnetic coupling mechanism. In order to illustrate the benefits of this structure, a prototype example is designed, fabricated and measured. Good differential- and common-mode performance has been obtained.