The circuit can be tuned to respond to signals between 50 MHz and 500 GHz. The economy model is shown in Fig. 1, and the deluxe model is shown in Fig. 2.The first op amp in each circuit functions as a current-to-voltage converter. In the economy model IClb buffers the output to drive the piezo buzzer. The deluxe model functions in a similar manner except that IClb is configured as a 20 buffer amplifier to drive the LM386. In both circuits Cl functions as a `transmission line` that intercepts the incident radar signal.
The response may be optimized by trimming Cl's lead length for the desired frequency. Typically the capacitor's leads should be 0.5-0.6 inches long.