This is one of my favourite antennas for the 30m band. It’s long, very long but, gives excellent gain in two directions for working DX. I had it oriented such that it beamed north over the pole and south towards Africa, great for working VK/ZL and South Africa & Antartica on CW.
I used this antenna all the time when I lived in France (F5VKM), having a large field just for antennas opened up a lot of possibilities.
Each leg of the dipole is 51.5656m long with the centre being exactly 14m above the ground. The antenna has maximum gain off the end of each leg so, make sure you rotate it such that the ends of the dipole legs face the directions you want to beam towards.
The dipole can be fed directly with 50 Ohm coax or a 1:1 balun, it gives a very useable SWR across the band.
I tuned the dipole so that it was resonant towards the bottom of the 30m Band but, you can centre the SWR curve by shortening each the leg of the dipole until you get the best SWR reading where you want it.
This might be a very simple antenna but, in this configuration it provides plenty of gain.
At 18deg there’s 9.84dbi of gain in each direction, at 9deg there’s 6.95dbi of gain and at 6deg 4.28dbi of gain. Working VK/ZL was a lot of fun with this antenna even with moderate amounts of power.
I wish I had the space for this antenna here at my U.K. QTH as it would be superb for FT8 contacts.
The Azimuth field plot shows where the max gain is obtained in relation to the antenna position. If you point this antenna East/West then you’re going to get global coverage with ease.
Below is the 3D Field Plot showing the low angle and high angle gain.
Plot
Summary:
Each Dipole Leg: 51.5656m (103.1312m Total Length)
Wire Dia: 2.5mm
Height at Centre: 14m
Impedance: 50 Ohm
Feed Type: Centre feed directly with Coax cable or via a 1:1 Balun for best results.