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Author Topic: Which band is best for very short distance communication (low power)?  (Read 360 times)

JOACHIM

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Which band is best for very short distance communication (low power)?
« on: November 10, 2019, 03:55:21 AM »
Hello, beginner here.

Which band would work best for communication within 5 kilometers at low power?
Only some small hills in between the transmitter and receiver.

Regards
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KG4RUL

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Re: Which band is best for very short distance communication (low power)?
« Reply #1 on: November 10, 2019, 04:52:11 AM »
An excellent way to predict coverage on any particular frequency is the Radio Mobile Online program https://www.ve2dbe.com/rmonline_s.asp

Basically, you input the frequency and details about the two stations and it creates a map of expected coverage.
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KH6AQ

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Re: Which band is best for very short distance communication (low power)?
« Reply #2 on: November 13, 2019, 12:56:07 PM »
Is this for mobile or fixed stations? The reason I ask is that 160 or 80 meters are good choices but an 80 meter mobile antenna has relatively low radiation efficiency and would require more transmitter power. Vertical polarization would be best.


https://www.electronics-notes.com/articles/antennas-propagation/ground-wave/basics-tutorial.php

http://www.arrl.org/files/file/Technology/tis/info/pdf/8501031.pdf
« Last Edit: November 13, 2019, 12:59:41 PM by KH6AQ »
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KC0MYW

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Re: Which band is best for very short distance communication (low power)?
« Reply #3 on: November 13, 2019, 02:27:29 PM »
It would depend on just how big the "small hills" are, and what exactly you are trying to accomplish, but for that distance, I would think that 2m or maybe even 70cm would be viable options. I've easily covered more than that distance simplex between two mobile stations (antennas on the vehicle roof) but don't recall what power settings were in use likely 5, 20, or 50 watts.
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W0CKI

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Re: Which band is best for very short distance communication (low power)?
« Reply #4 on: November 13, 2019, 02:36:42 PM »
HT and a repeater.
Gary W0CKI
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K0UA

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Re: Which band is best for very short distance communication (low power)?
« Reply #5 on: November 13, 2019, 05:44:14 PM »
How low are the hills, 5KM is just over 3 miles, how low is the power?  What antennas..  If the country is fairly open two walkies on 146 mhz with rubber duckies and 5 watts each can make 3 miles easy enough.  Two mobile units at 20 watts each could make the 3 miles easily in hilly terrain.
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73  James K0UA
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