indoor mobile signal improvement

[kripacharya]

My indoor signal strenght drops to zero at some places inside my house.

So i'm thinking - what if I make a resonant Quad antenna and stick it on the roof, and another resonant quad and place it indoors, and connect the two with a good co-ax with maybe a matching (passive) network.

Would that help getting better signal indoors ?

 

[vfone]

What you are trying to do is a Passive Repeater.

Generally in WiFi passive repeaters are used Patch Antennas or Helical.
Quad antennas (or loop antennas) are not the best option for high frequencies. They are fine for frequencies below 50MHz.

Search the net and you can find a lot of ideas related to this topic:

http://www2.elo.utfsm.cl/~ipd465/Papers y apuntes varios/passiverepeater.pdf
http://www.microwavejournal.com/art...overy-of-microwave-cellular-signals?v=preview

 

[kripacharya]

Yes of course ... a passive (hence simplistic) bidirectional repeater.
This is not for WiFi (~2.4Ghz) but for the 900Mhz GSM band which would yield a quad of ~3.3" square, and hence quite compact & sturdy in itself.
I didn't realise that quads were only good at below 50Mhz !!?

Thanks for the url's, they helped. Anything further advise of a practical nature would be great !

 

[E Kafeman]

Some simplified math. Roof antenna gain +10 dB, cable loss 5 dB, indoor antenna gain +10 dB, total gain +15 dB. Transmission loss between indoor antenna and cellphone antenna ~20 dB at 1 meter distance. Remaining gain -5 dB.
Yes it will work with quad antennas, but a bit small indoor coverage.

 

[kripacharya]

The issue here is to somehow get some signal into the indoor space, which otherwise has virtually no signal - or at least too weak for the 'phone to use.

Now I am assuming that the signal loss is due to masonry/ concrete/ steel /etc whose attenuation is definitely greater than a co-ax. Hence anything which can help the signal get in/out would be useful.

The trick is in finding a viable & practical solution.

So as Kafeman calculated, if I can get a signal indoors which is only 5dB down, then even that would be better than a signal which is otherwise possibly (say) 20 dB down ?
Thats a gain of +15dBindoor

you see what I'm saying ?

 

[E Kafeman]

Yes it is correct, the signal would in my calculation be 5 dB below the outdoor signal. It is a somewhat optimistic calculation as a gain also is assumed for the indoor antenna, but at 1 meter distance would directive gain just a few dB as it is near field.
It also assumes that the antennas are very well tuned and matched for a gain of 10 dBi. Cable loss, including connectors, was assumed.
Losses in indoor antenna can be reduced by connecting phone directly to the coaxial cable or connect by a passive coupler and let a Bluetooth headset handle the indoor coverage.

 

[kripacharya]

So if i make a folded-dipole Yagi, or maybe a dipole-fed parabolic with a matched cable (RG58 ?) using a 1/2 wave phase shifter co-ax or a 1:4 balun (for the folded dipole that is, not the simple dipole).

I'm thinking a 11- 12 element yagi giving a gain of (hopefully) 12- 14dbd, and an aperture of around 30deg.
haven't done the calcs for the parabolic, tho' that will be much more compact at least.

Then i take this rg58 down & inside, and connect it to a low gain monopole above a virtual ground-plane - a large blank pcb basically.

would that do the job of a nice passive repeater ? all dimensions of course tailored to 900MHz GSM band which is the most popular used here.

Or am i missing something ?

 

[davenn]

Losses in indoor antenna can be reduced by connecting phone directly to the coaxial cable or connect by a passive coupler and let a Bluetooth headset handle the indoor coverage

That there alone is by far the best suggestion!!

Dave

 

[kripacharya]

That there alone is by far the best suggestion!!

Dave

only if you actually use a bluetooth.

So no one has ANY experience, or any practical advise about such a setup ?