AMATEUR RADIO  DIPOLE CONVERSIONS  
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
favorite 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 that it is cut for. Think of a dipole
as a longwire that has an insulator in the middle.
FREQUENCY  A dipole antenna will not only work well on the frequency that 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:
FREQUENCY  A dipole antenna will not only work well on the frequency that 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:
The picture above is a diagram of the old standby CLASSIC antennas... the
Dipole and the Inverted "V" antennas. They are shown superimposed on each other in the above representative drawing. The BLUE colored line is the dipole configuration. The COPPER colored line is the inverted vee configuration. The InvertedV is basically a straight dipole broadband antenna with high gain that requires a little less space than the straight dipole and requires only one long mast at the center. The base, or bottom of the 'V' is connected to the top of the mast. The end of one arm of the InvertedV is connected to ground via a terminating resistance, while the other end of the second arm is connected to the antenna feeder. The InvertedV antenna is an excellent antenna for static locations. On flat ground the InvertedV antenna radiates mainly surface waves, but can be used to generate space wave if erected on a hill. Both antennas can be constructed just about anywhere using any type of wire you may have and can be used with 5075 ohm coax or open wire ladder line and an antenna tuner. The use of an RF choke balun is highly recommended. Most antenna critics agree there is little difference in the performance of either the InvertedV and the straight dipole. The largest difference between the two antennas is the length of wire needed. InvertedV's usually require about a 5% shorter wire length per leg than the straight dipole. You could use the calculator to build a 75 meter dipole and then calculate an InvertedV for other bands suspended under it from the same support and feed both with the same line to your transmitter. A little experimentation may be required for adjustment of the Standing Wave Ration (SWR), tuning the 75 meter dipole first for lowest SWR and then the InvertedV. 
LENGTH CONVERSION FACTORS  
CONVERT FROM  TO  MULTIPLY BY 
mile (US Statute)  kilometer (km)  1.609347 
inch (in.)  millimeter (mm)  25.4 * 
inch (in.)  centimeter (cm)  2.54 * 
inch (in.)  meter (m)  0.0254 * 
foot (ft.)  meter (m)  0.3048 * 
yard (yd.)  meter (m)  0.9144 * 

