A multi-coupled line based microstrip diplexer with high figure-of-merit

ABSTRACT

Based on the multi-coupled line, a novel compact microstrip diplexer with high isolation and low insertion loss is developed. The presented diplexer consists of five short-ended parallel coupled lines to implement the desired channel selections while exempting the use of extra T-junction matching networks, as compared with the conventional case. The design concept is detailed and a prototype diplexer is developed and examined experimentally, where the two channels are of center frequencies of 1.8 and 2.4 GHz, respectively. On the other hand, a figure-of-merit (FOM) is, for the first time, presented to evaluate the comprehensive performance of a diplexer. Results indicate the demonstrator diplexer has a size of 0.18 λg×0.34 λg and a very high FOM of 19301. Measurements match well with the simulations.

KEYWORDS:

• Coupled line
• diplexer
• compactness
• microstrip

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [61601063]; Department of Science and Technology of Sichuan Province of China [2018JY0323].