| 摘要 |
<p>A microwave input circuit including a parametric upper sideband down converter for receiving an input signal whose frequency is not much different from the intermediate frequency produced at the output of the down converter. The down converter may be either of the series type or of the parallel type and has its signal input directly connected to a microwave antenna and terminated by the real antenna resistance (Rg) or the real antenna conductance (Gg), respectively, at the input signal frequency (fsl). The parametric down converter comprises a cascade connection of a parametric down converter stage and a parametric up converter stage with both of said stages being of the series type or of the parallel type. The down converter stage is terminated at its image frequency (fsp) with a real resistance (Rsp) or a real conductance (Gsp), respectively, and satisfies the following relation-ship for a series type down converter: where Rsl is the series resistance of the reactance diode in the down converter stage, or the following relationship for a parallel type down converter: where GDl is the conductance loss of the reactance diode in the down converter stage, due to Rsl.</p> |
