antenna - Cable length vs obstructions

tl;dr For minimal signal loss: a longer cable is better than solid obstructions. Right?

I would like to enhance (the non-existing) phone signal indoors and have been thinking of connecting an external antenna to one inside. Basically:

cell phone <-> whip antenna <-> RG-58 cable <-> aerial

So I was thinking where to place the indoors antenna. Should I try to minimize cable length or obstructions? I might have found a conclusion by researching for this question, but I would still like to verify my thinking.

As RG-58 has about a loss of 0.3 dB/m at 960 MHz (GSM), and a 15m cable run would mean about 4.8 db loss according to this online calculator, or about 1/3 (1W in gives 0.3W).

On the other hand, solid wood dampens the signal by 5-12 db. That means even a 2m stretch of cable to minimize loss would be for nothing if I had an additional timber frame or door for the signal to pass through.

Is my thinking correct?

P.S. Follow-up question on using 75 ohm vs 50 ohm cable here

Answer

Your observation seems correct but choice of cable is poor. Except doors are dry wood and that makes a big difference.

Use SAT or CATV coax with satellite dish but LNA removed but located above chimney.

You need a high gain direction rooftop antenna in order to act as a passive repeater to be much stronger than the direct phone signal levels, otherwise, it will be worse by adding another multipath fading error.

Old cheap sat. DTV dishes were only 5dB gain. Bigger ones , more precise ($) could get more dB gain. But this shows the ideal diversity ( beamwidth) vs antenna gain tradeoff. A whip is almost isotropic but not down the end of the conductor, so close to 1dB gain. It assumes direct line of site, so the miles is theoretical.

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This is like an ascii drawing of a house, ideal antenna aimed at tower above trees, with moot point about 75 vs 50 ohms considering coupling impedance between phone and whip antenna. SO I suggest you will need to wrap a few turns of spring telephone coil around mobile phone to couple energy to phone patch antenna.