Millimeter-wave Ultra-wideband Mixer

Millimeter-wave mixers are the key components of millimeter-wave systems and the performance of mixer directly affect the system performance. Millimeter-wave ultra-wideband technology has attracted much attention due to its prominent advantage of application on electronic war. In this thesis, an ultra-wide band millimeter-wave mixer hybrid integrated technique is presented, with the first design for 18-40GHz ultra wide band integrated double balanced mixer in China. The simulation, assembling and testing of the mixer are also given.Compared with the general standard waveguide, ridge waveguides have the advantages of wider fundamental mode operation bandwidth and lower cutoff frequency. So the mixer circuit was simulated and fabricated in standard 18-40GHz double ridge waveguide. The interface of LO and RF ports are standard 18-40GHz double ridge waveguide ports which are convenient to interconnect with other devices and systems and the IF port is standard SMA. RF and LO signals are transmitted with orthogonal-field structure respectively by double-sided fin line transition and antipodal fin-line transition, which attribute to a high LO and RF isolation in the same frequency band.In the design of wide band double balanced mixer, bond-wires have been widely used to extract IF signal in design of general double balanced mixer. However, in this thesis the IF transmission line is vertical to substrate in order to avoid employing bond-wires. Meanwhile, in order to solve the problem of too narrow width between two ridges of double ridge waveguide, the heights of two ridges are gradient reduced, which also make a contribution to improve impedance matching. By extending the length of inner conductor of the IF coxial, which improves the balance of the circuit and that is one of major innovation of this thesis.Finally, an 18-40GHz ultra wide band double balanced mixer was fabricated and tested. The measured results show that the conversion loss is less than 5.5 dB and the isolation between LO port and RF port is more than 25dB, and the return loss is more than 10 dB, compared with other similar products, it has achieved more significant results. As a key component of receive system, mixer plays an important role and it improves the performance of all system directly. This thesis is meaningful not only in military field but also in commercial field in practice.