Simple

Probably one of the simplest and most trouble free antennas has got to be the halfwave dipole antenna. With very little that can go wrong with this antenna while constructing its well within the capability of even a newcomer. With an efficiency in the 90%plus mark and the ability for it to be used without a tuner its suprising it gets overlooked as much as it does. The design below is for monoband use needing no tuner.If cut for 40m you should have a low vswr on 15m also and with a little tuning should get a vswr of less than 1.5 on both bands needing no tuner.

Firstly.I have put this antenna design on for any newcomer who's looking for a quick,efficient and cheap way to try out the HF bands.I have left out a balun and have coax fed the antenna for simplicity. The reader especially if new to the hobby may not have a balun to hand or be unsure which balun to use. Should you use a balun?. I would use a balun,even if it was only a simple choke balun at the feedpoint(see baluns).But will this work without a balun?. The answer is yes.BELOW you can see the current and voltage distribution on the half wave dipole. Note the voltage minimum and current maximum at the feedpoint.

How long should it be?

The above dipole is cut for around 150 mhz but can be built for any frequency you wish using the formula 468/f. This is 468 divided by the frequency you want the dipole for.This will give you the TOTAL length of the dipole.Divide this figure by two and this gives you the length for each leg of the dipole seperated by the feedpoint.(chock block in diagram) Its a good idea to cut a few inches longer to allow for tuning.

Construction

Ok lets make a 20m dipole. Lets go for roughly the middle of the band 14.200.You would use the above formula.468/14.200= 32 foot 9 inches total length.Now divide this by two. This gives a figure of roughly 16 foot 4 inches which is the length for each leg of the dipole.(Remember to cut slightly longer for tuning), so lets make it 16 foot 10 inches to be on the safe side.Its much easier to trim some wire off than add some.Now simply connect each 16'10" leg to the chock block and connect the coax in the same way as the diagram. It doesnt make any differance which way round the coax is attached or the length,just use what you need to get from where the antenna is located to the radio.All thats left to do is erect and tune the antenna.

Above you will see three popular ways of hanging a dipole antenna. The thick black RX line represents the coax.Where this thick line meets the antenna (thin black line) is the feedpoint and is where any balun would be placed on a coax fed dipole. Remember to get the antenna as high as possible.