Sunday, September 4, 2016

Simple Ham Radio Antennas--"Umbrella" Antenna for 80 MTRS and up. Post #886

"Umbrella" Antenna for 80 MTRS and up
(http://www.dxzone.com/dx32221/umbrella-antenna-for-80-meters.html).
Accessed on 05 September 2016, 00:25 hrs, UTC.
Reporter:  N4SPP.
Please click title or URL to read the full article.
Comment:

Here's an interesting idea for an 80 meter vertical antenna that doesn't require a lot of space.

The "Umbrella" antenna is basically a top-loaded vertical with an attached wire capacity top hat that is sloped down from the top of the antenna.  This antenna bears a striking resemblance to the discone antennas often used in VHF, UHF, and public service bands.  For better performance, you can connect the individual sloping wires to a perimeter wire "skirt."

The materials required for this antenna project are modest:

Two, 6.5 meter/21 ft fiberglass fishing poles or telescoping rods.
24 gauge wire.
300 ohm television twinlead.
An antenna transmatch (i.e. "tuner").
2 meters/6.56 ft of PVC pipe.
4 elevated radials, each about 6.5 meters/21 ft long.

The article is fully illustrated with diagrams, photos, and plots of performance.

Top-loading is a useful way to get 1/4 wavelength performance without increasing height.  When I retired from Pacific Radio Group, our AM station (KHLO-AM, 850 kHz) was using a top-loaded vertical antenna.  The antenna worked very well, considering the restrictions imposed by the tower's proximity to the Hilo, Hawaii International Airport.

Perhaps this "Umbrella" antenna is something you could use at your ham shack.
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