Study on Performance of A Novel Defected Microstrip Delay Line

In this paper, a novel defected microstrip delay line (DMDL) with low insertion loss and simple structure is proposed for phased array antennas. It is formed by etching a series of strip-shape grooves on the conductor of the microstrip transmission line. Compared with fixed transmission lines, DMDL has the ability of phase delay adjustment. The effects of substrate materials and key structural parameters on DMDL performances including phase delay and insertion loss are studied in detail, which has guiding significance for design and engineering applications of DMDL. The simulated results show that DMDL has a phase-tuning dynamic range of over 70 degrees with fifteen grooves on the microstrip line. In the range from 8 GHz to 12 GHz, the return loss is greater than 15 dB, and the insertion loss is less than 0.4 dB, which makes DMDL have a broad application prospect in the multi-beam feed networks such as Butler matrix, Rotman lens, etc.