Regarding "dipoles" there are a number of points that have been well
1. If the antenna is to be used for multiple bands, keep it nonresonant to
avoid feed point impedance extremes.
2. Shortened "half wave" antennas can still be quite efficient. e.g. 45-50
foot loaded elements on 40 meter yagis.
3.With a multiband dipole where higher SWR's are likely, by the time you
get up to 10m low loss line can save appreciable power loss. Open wire,
ladder line, foam filled, even good quality 300 ohm TV line(for lower
power), are all possibilities.
4. "Off center fed" antennas may allow finding good compromise feed
impedance point but balanced antennas have the benefit of relatively
5. A good "antenna tuner" is a great station asset. It's a virtual necessity
for multiband dipoles and allows full band coverage with single band
6. For low angle/DX work try to get as much current as high as possible.
Letting the end 10%- 20% drop vertically to get a total length that gives a
good feed point impedance will not effect the gain drastically. Remember
that the end of the antenna is essentially an open circuit and not much
current flows through an open circuit.
7. A level, multiband, horizontal dipole, used at a frequency where it is
much more than a halfwave long will have increasingly nice gain but will
have increasing narrow lobes and then develop directional lobes. If
possible consider a second dipole horizontally rotated by 45-90 degrees to
help fill in the notches.
8. There is no magic about a wire antenna being resonant if you're not
trying to match a feedline to it.
9. On top of all of these points are overlaid the practical considerations
of available real estate, supports, and finances.
Just to throw another log on the fire, don't forget about vertical dipoles -
effecient with no radials, low radiation angle, swap height for
So, What kind of antenna should you put up and how should you fee it ? It
all depends..................................... but have some fun at it !
Gene / W2LU
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