Optimal EFHW Configuration for Low Angle DX?

[ultravista]

Looking for configuration recommendations for running an end-fed half wave, or non-resonant wire, for best low angle radiation. My current configuration for a MyAntenna's 80-10 is top fed @ 30 feet sloping to 20 feet.

My primary interest if HF DX on 10-40 meters.

 

[prcguy]

1/2 wave up horizontal on 40m will give the lowest takeoff angle on most bands but its hard to get the thing up at 65ft. Second choice would be 1/2 wave up on 20m which would be about 32ft high horizontal. At that height 40m will be mostly NVIS but I can work coast to coast on 40m at night with one that low.

 

[ultravista]

prcguy - a horizonal positioned EFHW will have a lower radiation angle than a sloper, L, or V?

 

[prcguy]

prcguy - a horizonal positioned EFHW will have a lower radiation angle than a sloper, L, or V?

Its the height not the shape of the wire than favors low angle. You want the high current portion of the antenna at 1/2 wavelength above ground or multiple of that for low angle. Or you want the antenna vertical with the high current point at 1/2 wavelength high but that's a problem for an EFHW except when using it at the lowest design frequency. To work on 40m you would have to make it 64ft long or for 20m about 32ft long, otherwise it would be 1 wavelength or more and have lobes going everywhere.

BTW on 80m the high current point on your antenna is in the middle. On 40m there will be two and on 20m there will be four high current points spaced along the wire. In contrast, on a center fed 80m dipole the high current point on 80m is at the feedpoint and the same antenna on 40m would have two high current points, each in the middle of each dipole leg and so on.

 

[ultravista]

Thank you. Is there a cheat sheet for current positions by frequency/band?

 

[popnokick]

EFHW radiation patterns here -
Multiband End Fed Half Wave EFHW Antenna » Electronics Notes
And practical configuration info here -
https://palomar-engineers.com/wp-content/uploads/End-Fed-Antenna-Secrets-LAKESIDE-2017.pdf

 

[prcguy]

Thank you. Is there a cheat sheet for current positions by frequency/band?

Probably somewhere. Just calculate a half wavelength or 1, 1.5. 2.0. etc, and use that. 468 divided by frequency will give you a half wavelength in feet and 10ths of a foot. Multiply that by 2 for a full wavelength or 3 for 1.5 wavelength and so on.

For 40m that would be about 65ft for 1/2 wavelength and 20m would be about 33ft. An antenna at 65ft would be great for 40, 20, 15 and 10m which are all harmonically related. At 33ft it would be fine for 20, 15 and 10m.

 

[K6GBW]

Yep, no magic here. Get the thing 65 feet in the air and you'll get low angle. Most people put them up in the teens and twenties and then wonder why that can't talk to Hawaii. Height, height height!