New triangular microstrip loop resonators for bandpass dual-mode filter applications

The paper presents a new class of dual-mode microstrip filters based on triangular dual-mode microstrip loop resonators. The triangular shape of the loop eases the design of dual-mode filters by allowing simultaneous edge coupling to the two dual-modes from a single feed (microstrip). Two consecutive dual-mode loop resonators are also edge coupled to each other without changing the triangular shape of the resonators. Dual-mode pseudo-elliptic bandpass filters of orders two and four are designed and presented.