Home made Antenna

[Farhad Abdolian]

Hi Guys,
I came across this link:

http://helix.air.net.au/index.php/d-i-y-discone-for-rtlsdr/

The guy has made an interesting and low cost antenna to boost his reception.

I am trying to use an active TV antenna I had for my old TV and make an adapter to be able to use it with my device. Don't know when I have time to do it, but I am sure the quality of reception will be much better.

Best regards,
Farhad

[imo]

With active antenna the quality might not be better as the dongles are easy to overload with strong signals. It seems from experiments for lower frequencies the gain decrease is required. An amplifier needs a good narrow bandpass filter for the frequencies of interest..

imo

[Nicholas Kruft]

I too have experienced horrible intermodulation and other issues with local fm broadcasts with a decent antenna. I was using a 102" whip for cb though. I had clear reception of 2 seperate fm stations all the way into the 300mhz even with the gain at lowest settings.

[Random Walk]

He added those rings to his discone for structural stability (and of course the best discone would be made out a sheet metal) however, the effect of adding those conductive wire rings is an unknown factor.. although they are perpendicular to the signal path and hence, may not matter, I'm not at all sure about that..
it might not be good..

The guy has made an interesting and low cost antenna to boost his reception.

I am trying to use an active TV antenna I had for my old TV and make an adapter to be able to use it with my device. Don't know when I have time to do it, but I am sure the quality of reception will be much better.

You need to understand the concept of polarization.

A vertical whip antenna will be horrible for FM broadcast or HDTV because those signals are horizontally polarized. However, it will be good for mobile signals or DVB-T

http://www.antenna-theory.com/basics/polarization.php *** Try this one first
http://en.wikipedia.org/wiki/Antenna_%28radio%29
http://en.wikipedia.org/wiki/Polarization_%28waves%29

 

[imo]

These dongles require an attenuator placed between antenna and the dongle. When the strong signals enter e4k chip then create a big mess even the gain is set to lowest settings. I am thinking to use a pin-diode attenuator (it may work up to GHz).

imo

[Jens Stark]

While the discone project looked great, I successfully took another, much cheaper approach.

 

As I own a F-to-"TV-Antenna" adapter which fits my sticks, I took a length of coax meant for satellite receivers and built a coaxial dipole, as recommended somewhere else.

 

Use this page: http://www.ve3sqb.com/ for the calculation.

 

I did not want to solder, so I used cable ties to do all the connections, including the use of two to tie the antenna to a broomstick.

Total lenght was about 1.76m, I cut off 30cm off each end.

 

Took about 20 minutes to build with nothing but a sharp knife, some coax, some cable ties and a F connector. 

 

Reception is much better than with cheap amplified indoor DVB-T antennas.

 

Best,

    Jens