RTL Dongle - Stock Antenna

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siza
Posts: 6
Joined: Tue Oct 04, 2016 9:37 am

RTL Dongle - Stock Antenna

Post by siza » Thu Oct 13, 2016 7:16 pm

Hi all.

Sorry if this sounds like a silly question ;) , but....

The desktop antenna that ships with the rtl dongle, what sort of antenna is it? and

What are it's limitations and what can one acheive, using it with rtlSDR?

Many thanks.

joe36
Posts: 53
Joined: Wed Jul 20, 2016 11:09 pm
Location: Cass co. in. 46994

Re: RTL Dongle - Stock Antenna

Post by joe36 » Thu Oct 13, 2016 9:59 pm

If it is a small 6 inch or so whip.
It is all but worthless. It will receive anything that is strong enough that your dongle can but the efficiency is very poor below about 500 MHZ and not that good above.
If it is say a 3 foot telescopic whip. Then it is much better but still not a very good antenna.
It works but that is about it. The one redeeming quality is it will get you started. Beyond that you will soon want a better antenna. Build or buy, that is a choice but antennas are fun and educational.
Joe KA9UCN

SIGINT
Posts: 13
Joined: Wed Oct 19, 2016 10:19 pm

Re: RTL Dongle - Stock Antenna

Post by SIGINT » Wed Oct 19, 2016 10:28 pm

It depends. My first SDR dongle came with a 12 cm fixed length whip antenna - good as a 1/4 wave dipole at about 625 mhz.

Some dongles come with a telescopic antenna you can adjust to match the wavelength. Both of them benefit a lot from a ground plane - mount them on a sheet of metal - perhaps a cooking pot upside down :-)

I have received and decoded POCSAG message quite fine using the 12 cm whip even at 160 mhz, reception improved with a ground plane, but a dedicated ground plane antenna tuned to the frequency moved the noise level down about 30 dB in my house. Probably a combination of better Coax (RG58U), antenna further from noise making computers and power supplies etc.

With good antennas comes the headache of how to mount them outdoors with no complaints from wife or neighbours :-)

on1bes
Posts: 29
Joined: Sat Dec 24, 2016 11:03 pm

Re: RTL Dongle - Stock Antenna

Post by on1bes » Sat Dec 24, 2016 11:13 pm

You can modify your stock antenna in to a J-Pole or something like i dit. It's much better. See on my webpage 'on1bes project pages'.

Giftmacher
Posts: 17
Joined: Mon Aug 01, 2016 4:29 pm

Re: RTL Dongle - Stock Antenna

Post by Giftmacher » Thu Dec 29, 2016 6:15 pm

My stock antenna worked quite well for ADS-B.

joe36
Posts: 53
Joined: Wed Jul 20, 2016 11:09 pm
Location: Cass co. in. 46994

Re: RTL Dongle - Stock Antenna

Post by joe36 » Fri Dec 30, 2016 1:25 am

Although the smaller stock antennas work OK? At UHF. The one thing they share in common is a short piece of coax with a connecter to the dongel. They can be cut off and attached to an improved DIY antenna and often they screw on to the base were a wire extension can easily be attached. Cut to a resonant length at a lower or desired frequency without damaging the original antenna.

Joe KA9UCN

reble
Posts: 25
Joined: Wed Sep 16, 2015 10:21 am
Location: West Richland Wa

Re: RTL Dongle - Stock Antenna

Post by reble » Sat Mar 24, 2018 5:44 am

If your going to splice coax together 1st use heat shrink tubing rather then electrical tape. I find heat shrink tubing works better. And 2nd after you have soldered and covered the inter conductor with heat shrink. Then cover the inter conductor with a small peace of aluminum foil before soldering the shield back together. I find the aluminum foil helps the flow of rf power get past the splice better. Also there is connector adapters available from the dongel to the pl-259 connector and to the bnc connector. I have both, 1 of each. The adapter is better then splicing coax cable.

Steve KC7BYP
joe36 wrote:
Fri Dec 30, 2016 1:25 am
Although the smaller stock antennas work OK? At UHF. The one thing they share in common is a short piece of coax with a connecter to the dongel. They can be cut off and attached to an improved DIY antenna and often they screw on to the base were a wire extension can easily be attached. Cut to a resonant length at a lower or desired frequency without damaging the original antenna.

Joe KA9UCN

joe36
Posts: 53
Joined: Wed Jul 20, 2016 11:09 pm
Location: Cass co. in. 46994

Re: RTL Dongle - Stock Antenna

Post by joe36 » Fri May 14, 2021 2:09 pm

I think I might have been mis understood. I was not suggesting splicing coax. I was suggesting that a dipole antenna can be built by separating the center connector from the shield then ataching equal lengths of wire to both the shield and center conductor.
A cheap connector, a couple of binding post and 100-200 foot of thin wire would be a very nice economical addition to the items for sale on this very appreciated sight.
On the store page of this sight they do advertise 1:9 HF Antenna Balun and Unun both from Amazon and Epay
I do not think this to be a good choice for this application.
I found this on Alie,com
aliexpress.com/item/4000199824208
I am having no luck pasting the image
This one is under $2, free shipping

Joe Yard - Joe36

radiolistener
Posts: 84
Joined: Thu Jan 25, 2018 10:48 pm

Re: RTL Dongle - Stock Antenna

Post by radiolistener » Fri May 14, 2021 10:17 pm

it's just a random piece of wire

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