An introduction to low power FM transmission (or pirate radio basics...) part 4

How far will my signal go?

In theory, the range of a transmitted electomagnetic wave is infinite regardless of power used,
it continues until it encounters an obstruction. more power helps to overcome any obstructions.

but is limited by how far the transmitting antenna can effectively see!

If there is a clear line of sight between the transmitter and the receiver (nothing in the way)

it should be possible to receive the signal, the curvature of the earth can soon become a limiting factor

Sources of interference or other stations operating on the same frequency.

Basically the same as people shouting over each other in a room,
the loudest one(s) get heard, and its possible to seperate the sounds of the loudest people who
have a different pitch(frequency) voice

and remember: shouting is not polite, especially in public

Transmission power (Effective Radiated Power).

You could expect a 10w station to have around a 20 mile range with a reasonable antenna

http://www.veronica.co.uk/range.htm

As you may have noticed by reading the above, fm broadcasting can mostly be about
having your aerial as high as possible.
Maybe consider using balloons or kites to lift your antenna?
Here is some information on the subject:
Prior safety warnings:

1. Give a wide berth to power lines (unless you want to look like a sausage roll).
2. Be very careful about static (unless you want to cross the rubicon).
3. Pay attention to air traffic (unless you want to pay through the nose).

http://www.hard-core-dx.com/nordicdx/antenna/special/baloon.html
http://www.qsl.net/g4vgo/balloon_antennas.htm
http://www.chem.hawaii.edu/uham/lift.html
http://www.helikites.com/skyhook/aad.html
Want to go higher?
That could be a stratosferic solution: http://www.eoss.org/pubs/faqloon.htm
http://www.economist.com/science/tq/displayStory.cfm?story_id=3423026
Want to go even higher?
Where blue turns black before it comes back:
http://bordelon.net/freespace/radioflier-1/default.html
When you get so high, you may start thinking satellite

History of AMSAT
AMSAT Documents for New Satellite Users
Sounds from the First AMSAT Satellites
OSCAR project - Orbital Satellite Carrying Amateur Radio

Maybe these bakery sponsered guys will help you lauch yours??:
http://www.jpaerospace.com
Give us a slot on your program then?!:)
Don't forget - a good mast will help!

Been away from Mother England for too long? In need of gravy granules, daddies favourite and ash browns?
Well that should be alright! Maybe you miss London's highlights: promiscuity, DLR and pollution. In that case the London Pirate Listening Station may be of temporary salvation: http://scanner.irational.org/