The simplest (Low) antenna that will be useful for
working DX is a VERTICAL with a GOOD radial field,
which means 30 or more radials as long as you can make
them, up to 1/4 Wavelength.
A wire can be dropped from a tree limb for the vertical element
or you could stack 3 pieces of 1-1/4 inch diameter fencing,
with insulated guys.
See the ARRL Antenna Book or Handbook for illustrations.
Another good antenna is a vertically polarized Delta Loop,
fed 1/4 WL down from the apex. (Corner feed will work but
has a tilted orientation). Total Length = 1005 / F (MHz).
If the bottom wire is close to the ground, you will need to
shorten this by about 3%. Feed impedance is around 100
ohms which can be matched using a 1/4 WL (electrical)
75 ohm line (RG59) which comes to 46.6 ft on 40M or
(23.3 ft on 20M) if you use solid dielectric coax
(velocity factor 0.66).
With the high level of solar activity, 20M should also
be open most, if not all, of the night.
The MFJ 1793 vertical covers 80, 40, and 20 Meters,
standing around 35 ft tall. It requires radials and
insulated guys. Price is around $160. It is a good
design, both electrically and mechanically.
Tom N4KG
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/web/.
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|