maximum transmision range.

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snuz2001
Posts: 11
Joined: Mon Aug 26, 2019 6:40 am

maximum transmision range.

Post by snuz2001 » Wed Nov 27, 2019 4:04 am

I would like to transmit a 50w 411 mhz fm signal from an airplane at 10,000' altitude and receive it clearly on a 2000' mountain peak with a simple baofeng receiver with a regular shot antenna.

What will be about the max range for the airplane from me? Will a better receiver - can be a scanner too - will do a better job? which receiver will be the best? will a directional antenna on the plane improve the range a lot? which one?

Thanks.

snn47
Posts: 192
Joined: Tue Dec 27, 2016 11:00 pm

Re: maximum transmision range.

Post by snn47 » Fri Nov 29, 2019 11:32 pm

The theoretical Radio Line of sight (RLOS) is ~ 1.23 * (SQRT 2000ft +SQRT 10000ft) ~178 NM.

No one will be able to give you a reliable estimate for the actual achieveable range since there are many factors to consider, e.g. antenna gain and variation of real lobed antenna pattern,
the difference between min. (notches) and max. (lobes) gain, of the transmitter and receiver antenna, which will vary for ground and aircraft antenna. The path loss will vary with antenna gain variation with the elevations angles between of both antennas. Unless you are always in level flight, a further reduction due to varyation in flight orientation is likely. Speed is also a factor for how long the attenuation can be high.

snuz2001
Posts: 11
Joined: Mon Aug 26, 2019 6:40 am

Re: maximum transmision range.

Post by snuz2001 » Sat Nov 30, 2019 5:42 am

Thanks.

"The theoretical Radio Line of sight (RLOS) is ~ 1.23 * (SQRT 2000ft +SQRT 10000ft) ~178 NM".

Is this around 300 km?

snn47
Posts: 192
Joined: Tue Dec 27, 2016 11:00 pm

Re: maximum transmision range.

Post by snn47 » Sat Nov 30, 2019 10:53 am

1 NM = 1.852 km

179 NM ~330 km

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