Solutions for Protoype and Low-Volume Systems

This is an example of a custom four-channel C-Band Receiver uses a single conversion technique to translate incoming 5.56 GHz radar signals to a 60 MHz IF. The Receiver is divided into two polarization sections, each with a dedicated channel for the received signal and a second channel for a reference signal originating from the transmitter. There are two identical circuits in the Receiver, one reserved for vertically polarized signals, and the second for horizontal signals.

The main receiver path has a Low Noise Amplifier (LNA) followed by an image-rejection mixer. Because of the low IF, the image rejection mixer (IRM) insures that the noise figure will not be degraded because of the image noise of the LNA. Immediately following the IRM is a low-pass filter that rejects any residual LO leakage out of the mixer. IF amplifiers boosts the 60 MHz IF signal, which is then bandpass filtered and routed to the rear panel.  The overall gain of the main receiver channel is about 40 dB.

A Reference Channel is provided to simultaneously sample the transmitter signal. This channel is very similar to the main receiver channel, except that it has no LNA and uses a conventional double-balanced mixer and a lower overall gain.

The local oscillator is a tunable Dielectric Resonator Oscillator (DRO) operating at a nominal frequency of 5500 MHz. This DRO is tuned with a 0-10 VDC voltage that is connected to a rear-panel connector for AFC tuning.  The DRO output is split into two signals to drive the main receiver channel and reference channel.