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HF-Antenna made from wire -Ideas?

Posted: Wed Jan 10, 2018 12:37 am
by MunteanuRO
I have a RTL-SDR v3 unit and a chinese branded 100khz-1.7ghz, both have
direct sampling capability, anyway i thought of a long wire antenna but I live at the apartment so I have no place to put it
and whit antenna extended in the building (conected to ground) i receive only chinese radio so no DRM, no ham, no nothing... the only gateway to the world of radio waves is the window and behind it..only...
At home I have a lot of coaxial cables, copper wires or 220v wires and I would like to know if from those wires i can build an antenna for putting behind window without too many headaches, and in what configuration (loop, horizontal, zig zag, etc.)
the ideal thing would be to make an antenna that can also be grounded to eliminate the interference.. so any ideas?

Re: HF-Antenna made from wire -Ideas?

Posted: Wed Jan 10, 2018 1:46 am
by Aussie Susan
Amateur radio operators have that problem all the time (especially those that live in apartments or have various restrictions on what they can erect) with the added 'bonus' or wanting to transmit as well.
Try a Google search for 'stealth hf antenna' or 'limited space antenna' and you might get some ideas that might suit your particular situation.
Susan

Re: HF-Antenna made from wire -Ideas?

Posted: Wed Jan 10, 2018 9:58 am
by rtlsdrblog
You might try look into magnetic loop antennas too. They can sometimes work okay indoors, and they can be oriented to block out noise sources.

Re: HF-Antenna made from wire -Ideas?

Posted: Wed Jan 10, 2018 7:06 pm
by Kenn
It may not be possible to receive weaker HF signals from an indoor antenna. But you can improve over the stock whip antenna. Here's some things I've done in the past when in an apartment:

1. A ham-stick antenna for 40 meters on a mag-mount. Stick it on the metal railing of the balcony at night. It worked reasonably well.

2. A long section of thin white wire thumb-tacked on the wall near the ceiling. Go around corners, make it as long as possible. It can be configured as a dipole or a loop.

3. Take to radio camping and stretch out 200' of wire in the trees. On a mountain-top, the results are just phenomenal.


Speaker wire, phone wire, insulated or not, it doesn't matter much. Even thin wire works fine. Antenna tuners like what Hams use will match the impedance of the antenna to the RTL, and that does help peak a signal especially if the antenna isn't designed for the frequency you're on.

If you know the frequencies of the station you're after, you can make the antenna a specific length and get better results. For a dipole it's 468/frequency=overall length in feet. So for 7 MHz a dipole would be about 67 feet, that might be a challenge in limited space.


-K

Re: HF-Antenna made from wire -Ideas?

Posted: Sun Jan 14, 2018 5:39 pm
by AdamHI
MunteanuRO wrote:
Wed Jan 10, 2018 12:37 am
and whit antenna extended in the building (conected to ground)
just to make sure that I'm understanding how you have this set up, can you clarify how you have things connected to ground.

Everybody's other comments are right on.