Antenna less FM xmitter (Modified one)

[Naveed Ali]

Please post a circuit of antenna less FM xmitter if you have designed such on [email protected]. Looking forward for positive reply.

Antenna less means that it is not totally without antenna but antenna may be very small to be noticed perhaps a 1cm or so but it must have a long range and power output.

OK...
Modifications...

FM range = 88-108 Mhz
Power output = <2W
Range = About 500 meters

[Guest Alun]

An Electrically small antenna will work though the resistance will be lower and it will behave like a capacitor.

Just use a normal small FM transmitter and add an inductor in series with the antenna.

Check out these links for more info:
http://www-personal.engin.umich.edu/~lschulwi/Report16.PDF
http://www.hard-core-dx.com/nordicdx/antenna/wire/shortdipole.html
http://www.ee.surrey.ac.uk/Personal/D.Jefferies/radimp.html
http://www.borg.com/~warrend/guru.html

[audioguru]

Hi Alun,
You found some excellent articles about antennas. ;D

I don't think it is possible to use a tiny antenna then transmit a high power from it on the FM band. Unless you have gobs of power to waste.

[Guest Decade]

Hi audioguru!

You can run kilowatts into a tiny wire but I would worry more about a tiny coax with high losses  ;D

[Guest Alun]

I don't think it is possible to use a tiny antenna then transmit a high power from it on the FM band. Unless you have gobs of power to waste.

He didn't mention the power level I just assumed <10mW for a legal transmitter.

Come to think of there was no mention of the frequency either, he just said FM, you could build a reasonably efficient FM voice transmitter working at the bluetooth frequency of 2.45GHz.

[audioguru]

He said he wants long range with power.
The antenna on my cell phone is only about 2cm externally, with a lot more inside, and it is rated to transmit 1W.