Phase difference detector, 433.92MHz

Thread Starter


Joined May 3, 2006
Hi, I am hoping to detect the phase difference from a 433.92MHz carrier signal detected at two antennas, where one antenna is about a 1/4 wavelength further from the transmitter than the other.

The circuit looks as follows. I use PLLs to ensure phase lock on the carrier and pass the 2 signals to a phase detector:

Rich (BB code):
(Antenna 1)              (Antenna 2)
|                      |
(JFET AMP 1)              (JFET AMP 2) 
|                      |
(~433.92 MHz Bandpass 1)    (~433.92 MHz Bandpass 2)
|                      |
(BJT AMP 1)              (BJT AMP 2)
|                      |
(PLL1)                  (PLL2)
|                      |
|                      |
(PHASE COMP) -------------------------------|                           
I hope you can understand my circuit diagram. A second Bandpass filter after the BJT Amps would double the 6dB of the first to 12dB, so I will probably put those in each line aswell.

My questions are:

1) Do I really need the PLLs? Can I just put the antenna signals into the Phase difference detector without phase lock, or do I really need the VCO (powered) output?
2) If PLLs needed, what ICs do you recommend? Do I need special PLLs capable of locking onto a 433.92MHz signal? Or can I somehow use standard 4046/LM565??
3) What IC for final phase comparator? Anything special required?

I hope you can answer my questions!! If you can, then you have probably guessed that the circuit is designed to detect which antenna is closest to the transmitter source, within a wavelength as per diagram:

Rich (BB code):

    -------------------------------//------------------------- Transmitter

Antennae are about a foot apart, transmitter is off in the distance.