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Tuning
Tuning the COM-20VA 20 Meter Vertical Antenna is straightforward and intuitive. If you use an
SWR meter or an analyzer at the base of the antenna you will get the most accurate readings in a
timely fashion. Since the bandwidth of the antenna is wide the adjustment parameters are relatively
broad and fine adjustment is not usually necessary.
Note: For the purposes of these instructions the term “resonance” or “resonant frequency” is
defined as the point of lowest SWR and may be used interchangeably.
To adjust the low SWR point in the 20 meter band, merely adjust the length of the top tubing
section in the normal manner, i.e., making it longer lowers the 20 meter resonant frequency and
shortening it raises the frequency. The top element section is made moveable by loosening the
element clamp and then sliding the upper element section of the antenna either closer to the base of
the antenna or farther away depending on whether you want to lower or raise the frequency of
resonance. Be sure to tighten the clamp after making an antenna length adjustment.
Approximate Overall Length
The approximate lengths shown in these tables should also be used when making resonant radials
for an elevated mount antenna (feedpoint is 3 feet or higher from ground level). For ground
mounted antennas, resonant radials are not required.
When used to make a higher frequency monoband vertical, telescope the extra lengths inside of
each other.
Approximate Overall Length
Approximate Overall Length
Approximate Overall Length
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