There were several people that contacted me stating that the patch antenna I was building was not circularly polarized. Or if I had done any testing to see if it was in fact circularly polarized. Well I finally got around to doing some testing.

I work at a place that manufactures electronic equipment that must pass EMI/RFI compliance. Although we can not certify ourselves, we do have some very nice equipment and facilities to test our equipment to see if we come close to complying. This equipment is used regularly and it is difficult to get time on it for any personal experimentation. I finally had the chance to use this equipment and jumped at the opportunity to see if the simulations of my patch came close to reality.


Equipment used:

  • Agilent E7405A Spectrum Analyzer
  • Agilent E4423B RF Generator
  • Receive Antenna (forgot to get the manufacturer/model number)
  • RF Chamber filled with anechoic material
  • Interconnecting coax was all RG214



    • Agilent E7405A
    Spectrum Analyzer
    Agilent E4423B
    RF Generator
    Receive Antenna
    (Vertical)
    Receive Antenna
    (Horizontal)


    Test setup:

  • Agilent E4423B RF Generator set to 2.4 GHz and -25.00 dBm output
  • Receive Antenna placed 1 meter from all antennas tested



    • Patch Setup
    Dipole Setup
    20-turn Helix Setup


    And here are the results of my testing: in a nutshell, it's linear. Below are some screen captures of the spectrum analyzer clearly showing that I have ~3 dBm difference in signal level between vertical and horizontal receive antenna orientation. RATS!! I really wanted this to work. I am currently using this design on my 1M Channel Master dish and it works GREAT! Nonetheless, the results don't lie. Just to make sure I wasn't doing something stupid, I tested my 20-turn helix in the chamber. The results show ~0.5 dBm difference between vertical and horizontal. Just for fun I also tested my 1/2 wavelength dipole that I made. Yup, it too shows ~3 dBm difference between vertical and horizontal. Ok, I'm now convinced. Back to the drawing board. Stay tuned for revision 2 of the K3TZ Optimized LHCP Patch Antenna for 2.4 GHz!!


    K3TZ Patch
    Receive Antenna =
    Vertical
    K3TZ Patch
    Receive Antenna =
    Horizontal
    1/2 Wave Dipole
    Receive Antenna =
    Vertical
    1/2 Wave Dipole
    Receive Antenna =
    Horizontal

    20-turn Helix
    Receive Antenna =
    Vertical
    20-turn Helix
    Receive Antenna =
    Horizontal