The Vee Beam Antenna
If you're lucky enough to have the room, perhaps you may like to put up a multiband Vee Beam antenna for the HF bands.
The dimensions of this antenna were provided by Nick, VE3OWV... Each leg is 300 feet in length... I used galvanised
fencing wire with the ends spaced 170 feet apart... This is an unterminated Vee Beam which can be used as a
bidirectional antenna... If each end is connected to earth through a 600 ohm non inductive resistor the antenna is called a
terminated Vee Beam and the front to back ratio approaches about 3 S points... Even so the gain is slightly less than
the unterminated type...
The layout of the antenna and a radiation pattern of an unterminated Vee Beam...
For ease of construction, I sloped the antenna because of the height of the trees... The trees here are not very high so the
antenna runs from about 28 to 5 feet in height.. The direction in which the antenna runs must be carefully considered as it
has a narrow beamwidth, especially on the higher bands...
The tree in which the feedpoint is located...
If the ends are not terminated but left open, the SWR is higher across the HF bands and an external tuner and tuned
feeders may be needed to match it to the transmitter on all bands...
The feedpoint impedance is about 600 ohms, so I used a 600 to 50 ohm balun (12 to 1) at the feedpoint and ran
50 ohm coax to the radio...
The 600 ohm (12 to 1) balun...
In my case the SWR on the 40 and 80 metre bands is very high and on the 30 metre band about 4 to 1...
On the 20, 17, 15, 12 and 10 metre bands the SWR of the antenna is about 2 to 1 or less and the inbuilt
antenna tuner of my transceiver (an Icom IC-7600) is able to match it to the radio..
One end of the antenna wire...
Even though the SWR of the antenna on the lower bands is very high, the internal ATU of the IC-7600 is still able to match
it to the radio so operation on all HF bands is possible here... This may not be the case with some other radios though...
My other radio, a Yaesu FT-450 with an inbuilt ATU is not able to match the antenna on the three lower bands...
An antenna wire support pole...
As the frequency of transmission is increased the effective length of the antenna is also increased giving better performance.
Construction of the antenna is straight forward... Of course the higher in the air you can get the wire the better...
If you have the room it would be well worth your while giving an antenna like this a go...
73 - Rob - VK5SW
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