I live in a small country with many inhabitants.
We Dutch have a population
of over 16 million, and specially in the cities it is a big problem for
radio amateurs to have a satisfactory HF-antenna.
My wish was to realize a multi-band antenna matched
of 80-M to 10-M on my small lot. It was, after some sketching, possible to realize a
½λ of 80M long centre-feed dipole antenna with some folding. As the
animation shows, the resulting antenna has been well adapted to the
The highest point, above the chimney, is about
18 meter above ground and the low ends about 7meter. The maximum overall length of the antenna wire
is 2 x 10.21 meter, and just fitted to the available space. The feed-line
of 10 meter (an open wire feeder) gives a total of 20.21 meter per dipole
arm, just the theoretical optimum! . Dipole antennas should be installed as
a rule, but generally tolerate much slope and/or bending. The angling of the
right halve of my antenna therefore gave no problems.
To match the antenna's
impedance to my tranceiver (a Yaesy 757) it was necessary to realize (in my
situation) two antenna tuners to convert the symmetric antenna signal into
an asymmetric 50 Ohms signal, giving an adjustable antenna matching on al
bands (including the WARC bands) between 10M and 80M. In practice the antenna has been found to be reasonably sensitivity and satisfactory in every way.
Of course this antenna cannot perform miracles. With all the angling, there
are certain directions where the received/transmitted signal is stronger and
in some other direction there may be a dip. Hopefully not in the direction
op rarest DX! Yet with my maximum output of 100 Watt I have worked stations
all over the world and I it still surprises me that I can work DX stations
in the general direction of the antenna legs. Up to now (you never know what
the future brings) I don't have complaints about TVI (television
interference) even when I am operating with 100 Watts output.