# How far can my FM transmitter signal reach?

I have a working FM transmitter on a raspberry pi2. I'm running my FM raido at 103.3MHz, and the antenna that I connected to the GPIO4 is a 70cm copper wire.

More data:(checked with a multimeter between GPIO4 and pin6-ground)

• DC voltage: 1.2V
• AC voltage: 1.8V
• Current: 18.4mA

update: I manually checked the distance by tunning cell phone fm to 103.3MHz. it was around 20 meter.

My question:

1.How far is my FM transmitter signal going?(Is there a formula?)

2.How do i increase the transmitting distance?(amplify the signal)

• I am assuming that you are wanting to know how far your signal will reach in air, without anything in between? (It is impossible to answer otherwise.) Also, what do you mean by "how far"? Whether or not a signal can be received depends on a lot of factors including any amplification at the receiver.
– hazzey
Feb 3, 2016 at 22:53
• yes, in the air. what factor will be affecting fm signal to reduce it's power? Feb 4, 2016 at 9:07