New production or home made antenna 0-30 MHz for indoor

Discuss commercial and home made antennas.
Post Reply
otpisani
Posts: 4
Joined: Sat Oct 15, 2016 8:41 pm

New production or home made antenna 0-30 MHz for indoor

Post by otpisani » Sat Oct 15, 2016 8:49 pm

Hello,

Can someone suggest how to made good indoor antenna for 0-30 MHz band. Problem is that living in apartment on 4 flour, my room is
3.5 m x 5 m big, don't have problem with production antenna either.

From hardware side have rtl-sdr dongle and spyverter.

Robin.

rtlsdrblog
Site Admin
Posts: 2321
Joined: Mon Nov 19, 2012 11:54 pm

Re: New production or home made antenna 0-30 MHz for indoor

Post by rtlsdrblog » Mon Oct 17, 2016 1:32 am

With limited space and no way to get one outside, its probably best to go for a magnetic loop antenna. Though you won't be able to cover the entire 0-30 MHz with just one.

otpisani
Posts: 4
Joined: Sat Oct 15, 2016 8:41 pm

Re: New production or home made antenna 0-30 MHz for indoor

Post by otpisani » Mon Oct 17, 2016 10:05 am

Hello,

Thanks for answer, want to be more precise. I put power gain "0" on and with that option have strong signal around 1.5, 14, 24 and 28, between -30 and -40 dBFS (SNR 34 dB). Signal is strong and presume close. Can I with magnetic loop antenna cover that area, not interesting to listen AM radio over the horizon.

Robin

rtlsdrblog
Site Admin
Posts: 2321
Joined: Mon Nov 19, 2012 11:54 pm

Re: New production or home made antenna 0-30 MHz for indoor

Post by rtlsdrblog » Tue Oct 18, 2016 5:04 am

Do you mean you're seeing AM interference at those frequencies? A loop is very selective and will null out AM broadcast. You won't be able to cover the entire HF band with most cheaper loops, but there are some fairly wideband ones available.e.g. the wellbrook loop is well known http://www.wellbrook.uk.com/ALA1530PE-1.

Have a look on eBay, there are some for sale there too.

joe36
Posts: 36
Joined: Wed Jul 20, 2016 11:09 pm
Location: Cass co. in. 46994

Re: New production or home made antenna 0-30 MHz for indoor

Post by joe36 » Wed Oct 19, 2016 4:17 am

I am usually not one to put a product down but in the case of an antenna such as the Well brook loop or any so called wide band loop I would be more than cautious of the sails hype and look at the $20 worth of components that make up a loop of this nature.
Right off the magnetic loop works on a different principle than one of the wonder wide band doo all loops.
The magnetic loop works by the loop portion being an inductor that has sufficient surface capture area to be an effective antenna.
The inductor “loop” is coupled to a variable capacitor creating a resonate tuned circuit.
In a resonant circuit each successive wave reaching the circuit supports and sustains oscillating current and voltages 180 degrees out of phase between the inductor and capacitor. At resonance on a magnetic loop of mediocre design and material it is not hard to reach a 30 Db increase from the noise floor at and away from resonance. This means you have a narrow band 30 Db band pass filter. The oscillation within the loop is inductively coupled to maintain the Q of the circuit.
This type of antenna is vastly superior to the wonder loop.
I recently built a fast throw together loop out of ¼ copper tubing and an air variable BC tuning cap it was 44 inches in diameter and had a detectible tuning range of from 1.5 to 17 MHZ and what I would say excellent performance range of from 3 to 8 MHZ. You can scale the inductor up or down to change the tuning range. If you are using a TV dongle. The magnetic loop is an amazing antenna. Not only as an antenna but more importantly a tuned front end filter.
The Well brook loop and others of this nature are doing nothing but putting an amp and filters on a small non resonant piece of wire. It is broad band because they use a broad band amplifier. If put side by side with a magnetic loop within its designed frequency range. The magnet loop would be vastly superior and can be built for +/- $20.
Joe KA9UCN

otpisani
Posts: 4
Joined: Sat Oct 15, 2016 8:41 pm

Re: New production or home made antenna 0-30 MHz for indoor

Post by otpisani » Wed Oct 19, 2016 8:54 am

Can you share schematic for magnetic loop antenna or site link where can be found. It's look great according to specs that you mention.

Robin.

joe36
Posts: 36
Joined: Wed Jul 20, 2016 11:09 pm
Location: Cass co. in. 46994

Re: New production or home made antenna 0-30 MHz for indoor

Post by joe36 » Fri Oct 21, 2016 11:16 pm

Here is a good page with a lot of useful information on a magnetic loop.
https://www.nonstopsystems.com/radio/fr ... agloop.htm
Joe KA9UCN

otpisani
Posts: 4
Joined: Sat Oct 15, 2016 8:41 pm

Re: New production or home made antenna 0-30 MHz for indoor

Post by otpisani » Tue Oct 25, 2016 12:19 pm

Hello,

Joe36 thanks for information that you share on forum, personally I would like investing to build magnetic loop antenna, but don't have place to put antenna except my room, beside have dog who is always around my leg :-) .

Recently I saw on rtl-sdr.com review about rt820t2 v3 dongle in Al case specially made from rtl-sdr blog, they shipped that dongle with 2 telescopic antenna, what kind of quality can expect from this antenna compare to this antenna that have right now...

https://1drv.ms/i/s!AgTtpXlIRe8lhDHbS2gLOUU4DpJs

Robin.

loureed58
Posts: 41
Joined: Tue Jul 05, 2016 11:27 am

Re: New production or home made antenna 0-30 MHz for indoor

Post by loureed58 » Tue Oct 25, 2016 8:02 pm

The V3 dongle on RTL-SDR is excellent and the price is very reasonable as is the shipping time. Don't expect too much from the supplied antennae although they are well made and a good starting point

I really wouldn't bother with a Wellbrook antenna as in my view they are massively over-priced and actually not that good!

Look at some of the plans for homebrew antennae, I'm an enthusiast not a techie or expert constructor but some of the designs are very straightforward and not that complex to build and they work well!

Kind regards

David

loureed58
Posts: 41
Joined: Tue Jul 05, 2016 11:27 am

Re: New production or home made antenna 0-30 MHz for indoor

Post by loureed58 » Tue Oct 25, 2016 8:05 pm


Post Reply