Hi Robert,
yes, I have an extra diode. While the RF has negative polarity, the 3.3nF capacitor gets charged through the bottom diode. As soon as the RF has positive polarity, the top diode conducts, and the voltage across the 3.3nF capacitor adds to the RF voltage. So this detector works like a kind of charge pump, offering a higher output voltage at the same RF level. I hope to improve the sensitivity with this.
Concerning the terminator - yes I forgot to add a 50 Ohm resistor in my schematic. And, besides that, I used an external 6dB pad at the input, which I probably should have mentioned earlier. This improves return loss and definitely provides a DC path for the diodes.
Tobias
