| 摘要 |
<p>A frequency mixer-downconverter which can be tuned as either a single sideband mixer or a double sideband mixer and which has a wide tunable RF bandwidth and low conversion loss is disclosed. A highfrequency input signal is coupled from an input waveguide to a shielded suspended stripline. Two Schottky barrier diodes are connected proximate to the waveguideto-stripline transition, between the inner conductor and the outer conducting channel of the stripline. The two diodes intermodulate the input signal with a subharmonic pumping signal which is also coupled to the suspended stripline from a waveguide input. An intermediate frequency signal, at a frequency equal to the difference between the input signal and twice the frequency of the pumping signal, is generated as an intermodulation product and transmitted on the suspended stripline to an output. The downconverter can be tuned as either a single sideband mixer or a double sideband mixer by positioning an E-plane waveguide tuning short and an H-plane waveguide tuning short at the transition between the input waveguide and the suspended stripline,. For a single sideband mixer the tuning shorts are adjusted to provide at the input waveguide-to-stripline transition a reactive termination at the image frequency and an impedance match at the input signal frequency. The tuning shorts are positioned to provide the same impedance match at both the image frequency and input signal frequency for double sidebad tuning.</p> |
