All-In-One DIY Antenna for RTL-SDR?

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SebyPI
Posts: 2
Joined: Tue Jul 21, 2015 9:25 pm

All-In-One DIY Antenna for RTL-SDR?

Post by SebyPI » Fri Aug 21, 2015 11:10 pm

I am frustrated beacuse on every reception on SDR (FM, 2M,70CM,6M...etc) i must use
a 'dedicated' antenna, e.g for CB reception a 1/4 GP antenna or buy a sophisticated ant, sure if i install one
of this then FM reception (another e.g) or 2m band go very worse or vice-versa.. sure..on the net are x,y design of antennas
and flavours but i don't want to use it separately.. i have a receiver-only RTL-SDR doungle even whit DVB-T2 demodulator
and don't need a resonant antenna,..but stil want to get those wave lenghts .. It's a loop antenna solution ? this is god
for MF (MW) but also for VHF signals,.when i maked one whit a diameter about 1m+ H155 feedline, i was able
to pick up some CB's, shortwave radio even APT images from NOAA, but it's a kind of thinks to make those 'receive-loops'
better , or another style of antenna? THANKS (and sorry for my english i'm not american)

Hinermad
Posts: 13
Joined: Sat Sep 05, 2015 8:04 pm

Re: All-In-One DIY Antenna for RTL-SDR?

Post by Hinermad » Sat Sep 05, 2015 8:30 pm

A single antenna isn't going to receive everything well from AM broadcast (MW) to 2M amateur (VHF). Your best choice for receiving FM, 2M, and and other VHF frequencies is probably a discone antenna or the old Scantenna once sold by Radio Shack. There are other multi-band scanner antennas available but they work better on certain 2-way radio bands and not so well for things like FM broadcast. (You may see them on cars, a vertical antenna with 1 to 3 small plastic covered coils in it.)

Loop antennas usually work best over a very narrow range of frequencies, and must be built for the frequency in mind. A single loop won't cover from AM broadcast (1 MHz) to CB (27 Mhz) to 6M (50 MHz). What many ham radio operators do for those frequencies is hang a wire outdoors between poles or trees. Even a few meters of wire will help, but the longer the wire the more it will receive. You can also connect an antenna tuner between the wire and your receiver to help tune out interfering signals.

rtlsdrblog
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Joined: Mon Nov 19, 2012 11:54 pm

Re: All-In-One DIY Antenna for RTL-SDR?

Post by rtlsdrblog » Mon Sep 07, 2015 4:38 am

What type of loop antenna are you talking about? As Hinermad said, loop antennas are very narrowband so aren't really good for tuning to a wide range of frequencies.

There's really no such thing as an all-in-one antenna. This is mainly a limitation of physics, not of manufacturing or design.

That said, the best wideband antenna is a Discone or Scantenna, or you could also look up how to build a planar disk antenna. These have a relatively low SWR over a wide frequency range (not great, but low enough for receiving).

Hinermad
Posts: 13
Joined: Sat Sep 05, 2015 8:04 pm

Re: All-In-One DIY Antenna for RTL-SDR?

Post by Hinermad » Wed Sep 09, 2015 1:35 am

rtlsdrblog wrote:That said, the best wideband antenna is a Discone or Scantenna, or you could also look up how to build a planar disk antenna. These have a relatively low SWR over a wide frequency range (not great, but low enough for receiving).
I've been a ham for a lot longer than I'll admit (grin), but I'd never heard of a planar disk antenna until I found your blog. It looks like a neat idea, and a lot easier to build from scratch than a discone!

Do you know if anyone has ever tried making something similar with two hoops instead of two solid disks?

rtlsdrblog
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Re: All-In-One DIY Antenna for RTL-SDR?

Post by rtlsdrblog » Fri Sep 11, 2015 8:38 pm

Haven't seen anyone do it with hoops. Not sure how that would affect it. It may work with a mesh.

Screwballl
Posts: 3
Joined: Sun Oct 18, 2015 10:21 pm

Re: All-In-One DIY Antenna for RTL-SDR?

Post by Screwballl » Sun Oct 18, 2015 10:43 pm

Discone seems to be the best option for the entire frequency rage the default units can handle 25mhz-2ghz.
Simple easy build would be those steel tomato cages for $1-2 each.

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