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Wireless Communications/data link range L/S or C band


Hello Jerry,

My question is for a data link (Line of Sight). Say we are proposing to use a directional antenna in ground and omni antenna in aircraft. For this case if we use a C band or L/S band system the range will be same for same conditions (data rate antenna size vs..) C band hs more free space loss but the gain of same size antenna in C band is larger to compansate the free space loss exactly.

In theory ıf we use omni antenna both in ground and air L/S band will have less freespace loos (10 dB). So L/S band system will go 3 times higher than C band?. Can we say for omni antenna both side lower frequencies go higher distance. what is the situation in pratic?

kind regards

Hello Salim,

You are correct, the free-space propagation loss rises as the square of wavelength.  

This means for equal gain antennas the path loss will be higher for higher frequencies.  

It is possible to make up some or all of this with higher gain antennas at one or both ends of the path but higher gain means directional and the antennas must be aimed correctly.


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Jerry Hinshaw


RF and microwave engineering, hardware and systems applications. Avionics, satellite, and terrestrial communications. Space communications and navigation, geo-location services via satellite and ground-based wireless systems. Systems integration of RF and wireless services. Electric Utility RF Smart Meter (SmartMeter) and Smart Grid wireless devices and networks. Utility Distribution Automation.


30 years experience in microwave and RF systems engineering, radio hardware design and development.

about 20 articles, 2 patents

BSEE MSEE Communications Systems

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