ARLA/CLUSTER: Quantas antenas necessita ter a sua estação.?
João Costa > CT1FBF
Terça-Feira, 20 de Dezembro de 2016 - 12:50:29 WET
Ham Radio - How Many Aerials Do I Need?
When I was teaching the Radio Amateurs examination a lot of new people
often asked the question how many aerials do I need?
The answer was always the same you can never have too many aerials,
after all we have many radio bands and to work them all efficiently
you really need an aerial for each one, aerials work best when they
are tuned for the part of a band that you enjoy most.
It is out of the question for many of us to have an aerial on each
band we simply do not have enough space outside our modern homes and
of course you must take into consideration the neighbours and local
planning laws and agreements.
For the average Radio Ham a vertical aerial covering the two metre and
seventy centimetre band placed on a pole on the side of the house is
adequate, if you enjoy rag chewing around an area of ten to fifteen
miles from your home location. For those of you who are interested in
working further afield a beam aerial with 8 to 10 elements is a good
alternative. A beam can be a cubical quad arrangement or a Yagi
design, these aerials unlike a vertical have gain in one direction and
to get the best out of a beam you need to have a rotator to turn it
through 360 degrees.
We have a number of specific allocations within the High Frequency
spectrum, starting at Top band or 1.8 Megahertz and working all the
way through to Ten Metres at 28 Megahertz. We are looking at dipole
lengths from 264 feet at 1.8 MHZ through to 16.5 feet at 10 metres, a
wide range of lengths.
Once again to fit in separate dipoles for each of these bands is for
the majority of us totally out of the question. Aerial matching units
do not tune your aerial they match the various impedance you find
across its length of your aerial to 50 ohms, that is what your
transceiver needs to see to transfer the power effectively.
Not having spent time as a listener is in my opinion a huge draw back
for you when you get through the R.A.E. and apply for your licence,
without time spent listening you will get frustrated and a little
despondent when your aerial and transceiver does not perform to your
My advice is to spend some time listening and if you are a club member
talk to radio hams who have been involved for some time with our
hobby, and learn from their experience and knowledge, about bands and
aerials. Bands change all the time due to natural conditions; they are
affected by time of day and by seasonable changes.
Listening gives you a good idea of where your interest lies, do you
enjoy the lower bands where radio hams from your own country
communicate, or do you like the fun of listening thousands of miles
away? Decide what suits you and put up a single band resonant aerial
for that band, you will not only hear more but you will probably work
John Allsopp G4YDM
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