INTRODUCTION-The longwire antenna is a very effective antenna for the listener who wants to cover all of the shortwave bands from 530 KHZ to 30 MHZ. However if you have some favourite frequencies that you listen to on a regular basis you may wish to consider a dipole antenna. This antenna is a fairly easy to construct antenna and will give you better reception on the frequency it is cut for. Think of a dipole as a longwire that has a insulator in the middle.
FREQUENCY-A dipole antenna will not only work well on the frequency it is cut for, but also for the multiples of that frequency. For example if you cut a dipole for 7.0 Mhz will also work well on 14 Mhz, 21 Mhz and 28 Mhz. This way if you can pick and choose your frequency you can make one antenna work on two or three bands.
LENGTH- To find out how long the antenna should be all you have to do is fill in a simple formula:
468 divided by FREQUENCY IN MHZ = LENGTH IN FEET (with end effect calculated in)
300 divided by FREQUENCY IN MHZ = LENGTH IN METERS
That is the only formula you need ever know to build a dipole antenna.