A Turnstile antenna with a reflector underneath it makes a good antenna for space communications because it produces a circularly polarized signal pattern and also has a broad, high angle pattern.
Construction of a turnstile reflector antenna consists of two 1/2 wavelength horizontal dipoles that are oriented 90 degrees from each other (like a big X). Then feed one dipole 90 degrees out of phase of the second one. One problem with Turnstile Reflector antennas is that the structure to hold up the relector part can be cumbersome. Fortunately (some might disagree) I decided to build my turnstile antenna in my attic. This solves another problem in that I also don’t have to concern myself with is weatherizing the antenna.
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