Indoor TBeam; Outdoor Antenna; Lots of Cable

Somewhere I read that x feet of “RF cable” causes worse loss than x*100 miles of air.

Is anyone running a node “in their house” with an antenna “on a roof / mast” (Thinking one like for a residential TV antenna) connected by some cable?

I’m thinking about putting a 915mhz tuned antenna above(?) my aerial TV antenna on the pole attached to my house. I’m thinking about running some SMA cable from that antenna to a TBeam in my basement plugged into my mini-data-rack where all of my ethernet / coax connections terminate.

Is this idea bad because of the length of cable I’d need?

Might be better off running a 12v 2 wire 18awg cable out there into a weatherproof box. The signal loss in the antenna would be noticeable. I say 12v because I have a DLink camera powered by a 5V barrel jack and used a POE injector. The camera wouldnt power up with my original run, I had to shorten the cable for it to power up. Could be a combination of the 24awg wire and long cable run, but my similar cameras that use 12V work fine. Any voltage drop on the 12V will be fine for the 5V USB. I just run the 12V into something like this and a short USB cable for power.

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You can use this calculator to give you the estimate of your loss over different types of RF cable:

3db is 2x the power. It takes 6db (4x power) to get twice the range.

Another way to look at it is a 6db loss is half your range lost.

@satkiwii Suggested mounting the radio on your roof and running power to that location, that’s a good option.

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This is how I power remote devices that need 5v, then I can use a 12 or 24v brick and the cable loss will be negligible by the time it gets to the device.

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Hi All and hello from a new member :smiley:

This might be an old topic but in regards to the cable question I could not resist to reply, the cable is a very important part of any antenna setup as well, as coax cable has the unfortunate property of having loss of (Db) in regards of length en frequency, this is called the skin effect, every coax cable has it’s own attenuation properties so you cannot connect any length of cable to an antenna setup as this can result in to much loss resulting the receiver not being as sensitive as you wish so: for 50 ohm RG58C/U Coax Cable the loss on frequency 806-960 MHz and a length of 30.5 meters (100ft) will be 18.2 Db if you take a length of 3.5 meter of the same cable the loss will be 1.82 Db and a length of 0.35 meter will be 0.182 Db I hope this helps for those who are playing with Antennas etc
a nice reference sheet for various coax cable see link below:
http://rfelektronik.se/manuals/Datasheets/Coaxial_Cable_Attenuation_Chart.pdf

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Thanks @mark

Welcome to the project.

Thanks for the welcome,

I am still going through the firmware setup guide on github, hoping to load the firmware for my TTGO T3_V1.6 20180606 very soon to start testing and playing with Meshtastic :smiley: