Compact microstrip balun diplexer using stub‐loaded dual‐mode resonators

A new microstrip unbalanced‐to‐balanced (balun) diplexer based on stub‐loaded dual‐mode resonators is presented. The proposed balun diplexer primarily consists of two balun filter channels, and both channels are entirely independently designable, thus bringing great flexibility in the balun diplexer design. Besides, owing to the direct connection of two dual‐mode balun filters, no additional matching networks are demanded at the common input port, leading to a significant size reduction. For demonstration, a prototype balun diplexer operating at 2.30 and 2.72 GHz is implemented. Both simulated and experimental results are provided in good agreement.