Hi,
A basic question: transistors, diodes has maximum frequency rating. 1n4007 are slow, 1n5819 are fast and 1n34 are ultra fast diodes. What happens if I fed UHF signal to an ordinary LED? Does that glow? How much rectified voltage I get if I fed UHF 5V signal in a 1n4007?

Answer of these question helps me to make concept about diodes' frequency.

 

The junction switching speed (forward/reverse recovery time) and device (internal) capacitance are major factors. Large power diodes are slow because there is more to move when the voltage polarity reverses. At UHF a diode with a large junction capacitance provides a short-cut across the junction taking the diode mainly out of the circuit in actual operation. This capacitance changes with the value of reverse voltage so it can be useful. Varicap

http://web.iitd.ac.in/~shouri/eel201/tuts/diode_switch.pdf