Here is a great project notes for a 433MHz beacon and directional RX.
https://courses.cit.cornell.edu/ee476/FinalProjects/s2008/eky2_cc459/website/index.html

I found an RX similar to the one used at Mouser for $2 each. I think it was cheap since it was on clearance, and had some LPF on it that limited it to 4800 BAUD.
I got it because it has an analog audio output pin, which they seem to be able to use as a simple signal strength indicator.

I hope that I can use this, with a directional loop antenna as a transmitter locator. I want to mount the directional antenna to a servo to sweep around, and allow a robot to chase a TX.

Any suggestions on how to design/build a loop antenna?
I want loop instead of Yagi, since AFAIK the loop can be as small as 1/10 wavelength circumfrence, and I want to be able to sweep it with a simple hobby servo.