Author Topic: Long antenna cable possible?  (Read 465 times)

MrGlasspoole

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Long antenna cable possible?
« on: January 16, 2017, 08:16:06 PM »
I have the problem that i need the main microcontroller in the basement in the central heading room.
But i want the antenna in the middle of the ground floor to have signal around the house.

One way solving that would be using a small microcontroller with the RFM69 connected to the one in the basement via RS485.
But that makes coding complicated and i have to do code changes every time on two devices.

Is 6-8 meters antenna cable possible? Are there antenna amplifiers like for radio/TV?

captcha

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Re: Long antenna cable possible?
« Reply #1 on: January 17, 2017, 04:41:34 AM »
Anything is possible..

If you had a decently matched antenna (<1.5:1 SWR) and fed it with decent cable you could lose up to 30% of your power with 6m of RG-8X @ 868MHz. LMR-400 will hold up better with about 17% loss. Just for fun, RG-58 will cut your power in half and RG-174 takes a whopping 75% away.
http://kv5r.com/ham-radio/coax-loss-calculator/

SWR higher than that and you might as well use a flashlight for your signaling protocol.. :)

My suggestion would be to extend your sensors from the basement to the ground floor.