Dipole Antenna Length

When determining how long to make each leg of a Dipole antenna, dividing the frequency in MHz into 468 will give the overall length. To find the half wave, divide that number by two. This will give you the length of each leg of the antenna.

Example — 80 meters: If you are operating on 3.8 MHz, dividing 3.8 into 468 gives 123.16 feet over all. To find the half wave, dividing 123.16 feet by 2 gives 61.58 feet for each leg. Cut the wire two or three feet longer so you will have some to fold back on itself when adjusting the SWR. The part that folds back on itself does not effect anything. Connect the co-ax at the center point or middle of the antenna, the center lead of the co-ax to one leg and the braid to the other leg. When adjusting for minimum SWR, adjust each leg the same amount, current fed.

Example — 40 meters: If you are operating on 7.2 MHz, dividing 7.2 into 468 gives 65 feet over all. To find the half wave, dividing 65 feet by 2 gives 32.5 feet for each leg. Cut the wire two or three feet longer so you will have some to fold back on itself when adjusting the SWR. The part that folds back on itself does not effect anything. Connect the co-ax in the center point or middle of the antenna, one leg to the center lead of the co-ax and the braid to the other leg. When adjusting for minimum SWR, adjust each leg the same amount, current fed.

Example — 20 meters: If you are operating on 14.5 MHz, dividing 14.5 into 468 gives 32.28 feet over all. To find the half wave, dividing 32.28 by 2 gives 16.14 feet for each leg. Cut the wire two or three feet longer so you will have some to fold back on itself when adjusting the SWR. The part that folds back on itself does not effect anything. Connect the co-ax in the center point or middle of the antenna, one leg to the center lead of the co-ax and the braid to the other leg. When adjusting for minimum SWR, adjust each leg the same amount, current fed.

Example — 2 meters: If you are operating on 144.5 MHz, dividing 144.5 into 468 gives 3.24 feet over all. To find the half wave, dividing 3.24 feet by 2 gives 1.62 feet for each leg. When mounting on a vehicle, a quarter wave antenna MUST be mounted on a metal base. A half wave antenna can be mounted on a fiberglass or plastic body vehicle with the co-ax connected to one end of the antenna, center lead to antenna, braid grounded, voltage fed.

Adjust the wire connected to the center lead of the coax for max output and then adjust the wire connected to the braid of the coax for minumum SWR.

The following form may be used to calculate the optimal antenna length for a specific frequency.

Please provide the following.