The CAD Design Of UHF Microchip Junction Circulator

With the fast development of telecommunication, as for the traveling carriage orbase station of IS-95, W-CDMA, CDMA2000,the demand for the emission andreception of signals is higher and higher. Considering of the safety requirement, thereshould always be an isolator behind the power amplifier in order to protect thecomponent from being destroyed by the powerful signals.Isolators and circulators are widely used in radar, electronic countermeasures,telemeter telecontrol, microwave measurement and so on. Isolators and circulators areone way transmission components. Their effects are indispensable.This paper gets a few conclusions by bringing the analyses of the magnetic fieldin three port circulator into S-parameter matrix. According to these conclusions, arapid and accurate CAD design of the Y-type junction circulator has been made. Thena Y-junction circulator which works at 2140 MHz has been made and simulated. Atlast a real circulator has been made and the result proves the characters of Y typejunction circulator will change with the different value of bias magnetic field and thisway need less value of bias magnetic field comparing to the traditional circulatordesign. Except that this paper also prove this way should not been used in 940MHz.Then this paper improves the design and sums up the design form of double-Ytype junction circulator. The simulating results and the real test results all display theIL can reach to 0.25dB and isolation can be more than 35dB.In the finality, the problems requiring further studies are discussed.