Balanced circulator structure with enhanced isolation characteristics

Abstract

In this article, we proposed a new balanced circulator structure having enhanced isolation characteristics between transmitter and receiver. Also, we show that the balanced circulator structure has little performance degradation for the varying load impedance. The balanced circulator consists of two branch-line couplers and two circulators. The validity, of the balanced circulator is confirmed by, comparisons with the simulated and measured results obtained from the single circulator The fabricated balanced circulator has about 50 dB isolation for the matched load impedance and above 30 dB isolation for the mismatched load impedance at 910 MHz, the center frequency of UHF RFID. (C) 2008 Wiley Periodicals, Inc.