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Quadrifilar Helical Antenna

VSWR-Frequency Comparisons Chart


Hardware Store QFH
Our own antenna, made from very inexpensive materials...


NASA Mars Rover QFH
NASA's antenna, which cost about $10,000 to make.

The Quadrifilar Helical Antenna is one of the most interesting antennas that I have developed. Initially it appears to be complicated, however once the concept is understood, it is actually not complicated. This design is different from the initial design found in QST Magazine (REFERENCE). The Z is matched via the coil of helix at the base of the feedpoint, located at the top of the antenna. The bandwidth is wide (please see the VSWR graph at the top of the page). This type of antenna is not terrestrial. It is designed to be pointed like a rifle at it's intended target. The half power bandwidth is approximately 120 degrees with 0dB gain.


Antenna Converters

Frequency (MHz):
λ:  
XcTotal Wire Length: XLTotal Wire Length:
XcAxial Length: XLAxial Length:
XcØ: XLØ:

Converters designed by Michael Castillo

The answers given here are in inches, not feet.


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