Antenna No 58
4m Delta Loop
I made this antenna for use on my SOTA activities. It is similar in
construction to my 6m Delta Loop, it is reliable and quick to set up under
almost any WX conditions.
Diagram of the 4m Delta Loop antenna.
The 'test' antenna was mounted on a fiberglass mast, the horizontal wire
being about 6m above ground level.
The antenna in "Nabla" form (an upside-down Delta), for
Coax: H-155 (50 Ohms) or equivalent cable, to transceiver.
Coax RFC: quarter wavelength = 0.66m of RG-59 (75 Ohms) or equivalent.
Add 2cm to each end to strip (total length of coax is 0.66 + 0.02 + 0.02 =
0.70m). Solder 6mm cable shoes at the RFC end.
Fiberglass pole, 10m total length (10 sections).
Stainless steel M6 bolt, nut and washers (x2).
Wire = field telephone wire, military surplus. Simply solder the 2
wires together. Use 6mm diameter cable shoes at ends.
N or PL connector.
Electrical conduit (PVC, 20mm diameter). I use 2 x 0.72m sections for
Recycled plastic cylinder for RFC (e.g. empty silicone tube), 50mm
Antenna measurements September 2014.
SWR curve of delta loop in horizontal
Antenna SWR is very low, < 1.3 across the entire 4m band.
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