Miniaturization of Rat-race coupler with Harmonic suppression technique

In this work, a compact RRC using a T-shaped line configuration, in place of all 90° conventional transmission line sections is presented to achieve broadband suppression of harmonics. A lossless transmission line model is derived for the design. As the design is not composed of any complicated structures, via holes and lumped elements, it is simple to implement and easy to fabricate.