2016-05-05

I have constructed a loop antenna from a SMA female-to-female adapter and a lenght of thin wire. I secured teh bottom plate to the cavity with 4 wing bolts and wing nuts. I inserted a straight antenna through a 3/8" hold about midway up the chamber, and inserted the loop antenna below the midpoint through a 1/4" hole. I prefer the 1/4" hold. Neither antenna was strongly secured, and the female-to-female adapter was connected physically (resting) to teh chamber wall. The straight antenna was connected to the RFExplorer Signal Generator. The loop antenna was cnnected to the RFExplorer Spectrum Analyzer and arranged approximately horizontal, parallel with the bottom plate. The settings of the devices are recorded later. The data recorded by the RFExplorer software is in file RFExplorer_SweepData_2016-05-05-22-28-52.rfe. The data show a steady peak at 2403.964 MHz that corresponds to turning the Signal Generator on and off. Using the contiguous data points 2403.429 MHz @ -91 dBm, 2403.964@-74dBm, and 2404.500@-90dBm to calculate Q, I get Q=2,244.598. I find this suspicious for several reasons:

  1. this is using contiguous data points, so it is more likely a commentary on the resolution of the equipment, meaning it is AT MINIMUM 2,244, and
  2. this seems suspiciously high considering I'm basically a mook and this is my first attempt.

This was done with:

  1. insufficient polishing,
  2. no silicone coating,
  3. no special geometry such as spherical endplates.

There remains in this experiment:

  1. tie the resonant frequency back to the actual dimensions of the cavity and
  2. resolve the resonant frequency with the ac of that frequency, and compare that to teh actual a of the cavity.