Monday, December 23, 2013

Simple, light weight, stealthy QRP dipole

In a few weeks we will move from our current QTH, with room for antennas, to a flat on the 28th floor, with a small balcony and restrictions on what can be put out there. (We'll be back but not for 8 months).

I have a new interest in stealth QRP antennas and have been experimenting...

Targeting 20m, I've built this very successful dipole. The wire is 10.1m, cut in half, with the ends folded back on themselves for tuning.

The feed line is thin RG-174 co-ax that runs directly in to ten turns on an FT114-43 toroid. A twin screw terminal block is used to attach the dipole wires. The design comes from n5ese but has been further simplified.

Everything is held together with cable ties and it's light enough to be suspended by the dipole wires. At resonance the SWR is very low but for some reason the impedance is a little low too.

The FT114-43 should work on any band from 0.5 to 30MHz by the looks of it. My plan is to use this for 10W which should be fine.

I'm looking for better options for connecting the legs of the dipole but the screw terminal block will do for now. Waterproofing is plastic wrap for now.

This probably won't survive very long.

This arrangement is very light, removes the need to have a connector at the balun, which saves both an potentially crackly connection and the weight of plug and socket. Running RG174 coax is light and less visible than other alternatives.


I've had a series of test contacts with Mal, VK2BMS. This antenna is better than the short Ozi-pole dipole but not as good as a full dipole on the roof - pretty much what you'd expect.

1 comment:

Indy said...

Hi Mark,

I would love to hear about QSOs with the antenna. N5ESE's Notebook antenna may be an option in small spaces - Have you considered a magnetic loop antenna? I am getting mixed results with a homebrew end-fed built using the recipe here -

Wish your move goes well. Merry Christmas!