Dual-Band Butler Matrix with the Same Phase Difference for Long-Term Evolution Applications

ABSTRACT

A novel dual-band Butler matrix is proposed with the same phase difference, aiming at the interest of long-term evolution. The total circuit simply includes four 3-dB 90° dual-band couplers and two 45° broadband phase shifters, which are capable of operating at two separate frequencies. Due to the utilized 45° broadband phase shifter, the phase differences remain invariant at two unrelated frequencies between the adjacent outputs. This Butler matrix can be easily fabricated by using single-layer microstrip technology. The measured results of a prototype demonstrate that it can operate at both 1.85 and 2.7 GHz, which perform phase errors and coupling ratios within 5.44° and –6.63 ± 0.72 dB.

KEYWORDS:

• Butler matrix
• dual-band
• same phase difference

Additional information

Funding

This work was supported in part by the National Basic Research Program of China (973 Program) (No. 2014CB339900), and in part by the National Natural Science Foundation of China (No. 61422103 and No. 61327806).