Sunday, June 2, 2019

Sloper and half sloper antennas

The typical suburban DX oriented ham is likely to have, as a minimum, a tower, rotator and 3 element trapped yagi for 10, 15 and 20 metres.  They will likely want at least 40 and 80 metres which, if they are not seriously into DXing, can be an inverted-vee, with the tower being the high support. 

Another option is something often called a sloper. These can also act as guy wires for the mast. A full sloper can be an ordinary half wavelength dipole. One end is near the top of the mast. It droops down at an angle (say 45 degrees) to be tied off at a post above head height. Such an antenna can give good DX performance, and being a full dipole, is not dependent on an extensive ground radial system. Its main disadvantage is the tower height required. That's beyond the scope for some hams for a 7 MHz sloper (20m long) and almost everyone if you wanted to build one for 3.5 MHz (40m long). And 160 metres would be out of the question. 

Another possibility is what's sometimes called a half sloper. This is basically a bent up half wavelength dipole, with a quarter wavelength of wire sloping down to the ground.  It (again) forms the hypotenuse of the triangle formed by the mast and the ground.  The feedpoint is at the top. The half sloper's other side drops straight down. It might be run along the ground if the mast is too short. 

Here are some articles if you'd like to read more about slopers: 

* VE2DPE's slopers 
* Eham forum discussion on 80 & 160m slopers

PS: Like something to read? Books by Peter Parker VK3YE are 
read worldwide and have been favourably reviewed.  Available in both electronic and paperback.

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