How far in communication range, can I get with my Icom IC-A24E Aviation radio?

We recently had this question sent to us on our Facebook page. My first thought was the answer would depend on where and how high up your were flying. I forwarded the question to one of our engineers who gave me this fabulous equation explaining the answer.

Free space attenuation (line of sight)

Formula : Lb = 32.45 + 20 Log f + 20 Log d.

Where Lb = free space attenuation dB

And f = frequency in Mhz

And d = distance in Kilometres

For 128 Mhz at 100 Km (approx 62 miles) this gives a path loss Lb of 114.6 dB

Since the transmitter of an A24 is + 35 dBm (pep), this will give a path signal of 114.6 – 35 = - 79dBm. The Rx sensitivity of the A24 is –113 dBm for 6 dB s/n, so therefore the Rx capture will be 34 dB above the minimum spec.

The above calculation assumes no feeder loss, direct line of sight, and 0 dB aerials.

11/07/2014