Author Topic: Passive longwire cellphone antenna to inside dead area?  (Read 1086 times)

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Online Circlotron

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Passive longwire cellphone antenna to inside dead area?
« on: June 20, 2018, 10:30:08 am »
At work I am stuck inside one of those portable site office buildings that is all aluminium clad, and this in side a concrete walled factory. Phone reception is zero inside my little Faraday cage, but reasonable in the factory area. Might there be some improvement if I strung a length of wire outside in the factory area and passed it through the window to my work area? Not expecting amazing results, just something better than zero.
 

Offline Yansi

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #1 on: June 20, 2018, 10:46:01 am »
Strongly doubt it would help anything, apart from catching few thunderstorms.  :)

Get a proper external phone antenna, if you phone supports connecting it.
 

Online Marco

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #2 on: June 20, 2018, 11:04:13 am »
I doubt many modern smartphones have external antenna inputs any more, but older ones did (google tells me Samsung S4 had it for instance).

You might be able to get a cradle for your phone with an external antenna port though which I assume just puts another antenna right next to the phone antenna to couple the signal. Which you can then connect to an antenna in the factory hall.
 

Offline rx8pilot

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #3 on: June 20, 2018, 11:17:36 am »
This is a task for an active amplifier. A number of years ago, I purchased a system from a company called Wilson. It was pricey, difficult to install, and did not do much to help signal strength.

Maybe modern options are better and lower cost.
Factory400 - the worlds smallest factory. http://www.youtube.com/c/Factory400
 

Offline thermistor-guy

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #4 on: June 20, 2018, 01:00:45 pm »
At work I am stuck inside one of those portable site office buildings that is all aluminium clad, and this in side a concrete walled factory. Phone reception is zero inside my little Faraday cage, but reasonable in the factory area. Might there be some improvement if I strung a length of wire outside in the factory area and passed it through the window to my work area? Not expecting amazing results, just something better than zero.

Good question. RF isn't my area, but your post did bring to mind these concepts:

https://en.wikipedia.org/wiki/Leaky_feeder
https://en.wikipedia.org/wiki/Passive_repeater

I'm keen to read what RF experts here advise.
 

Offline babysitter

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #5 on: June 20, 2018, 04:43:37 pm »
Either you use the already recommended leaky line (Preferrably directional antenna outside, inside the leaky), or you use a path which i think is even easier to DIY in my opinion but obscure technology from days gone.

Gubau line:

This consists of a single wire, preferrably isolated, wire strung to to the "dead" area. Coupling from coax is done by a kind of trumpet like this:

<------------------------------------------------------------------------------

at the small opening of the trumpet you attach the coax to the outside antenna. The trumpet shape shall actually be trumpet-like, not like a funnel.


I'm not a feature, I'm a bug! ARC DG3HDA
 
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Online Circlotron

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #6 on: June 20, 2018, 04:52:18 pm »
Looked at using a waveguide but the crosssection needs to be about 12x6 inches for 950MHz.  No good.
 

Offline thermistor-guy

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #7 on: June 21, 2018, 10:40:50 am »
Either you use the already recommended leaky line (Preferrably directional antenna outside, inside the leaky), or you use a path which i think is even easier to DIY in my opinion but obscure technology from days gone.

Gubau line:

This consists of a single wire, preferrably isolated, wire strung to to the "dead" area. Coupling from coax is done by a kind of trumpet like this:

<------------------------------------------------------------------------------

at the small opening of the trumpet you attach the coax to the outside antenna. The trumpet shape shall actually be trumpet-like, not like a funnel.

Fascinating concept. Thanks.

https://en.wikipedia.org/wiki/Goubau_line
https://en.wikipedia.org/wiki/Single-wire_transmission_line
« Last Edit: June 21, 2018, 10:47:24 am by thermistor-guy »
 

Offline CopperCone

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #8 on: June 21, 2018, 11:07:34 am »
how do those amplifiers work since their bidirectional antennas? Do you have a active circulator or something (to keep size down at 900MHz?)
 

Online jmelson

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #9 on: June 22, 2018, 07:02:18 am »
There's a thing called a passive repeater.  It has a Yagi antenna on the roof pointed at a cell tower.  They run heliax down inside the building, and then have a small antenna in the area where people need cell connection.  I sometimes am in a building where they have this, and it does work.  Both antennas are tuned for the cell frequencies.  A piece of wire is not going to do the job.

Somewhat more sophisticated systems have directional couplers on the heliax and multiple small antennas in different areas inside.

Jon
 

Offline David Hess

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #10 on: June 22, 2018, 07:39:22 am »
Install a passive repeater.  Place a phone band antenna on the roof and connect it to another phone band antenna inside the room through coaxial cable.
 

Online jmelson

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #11 on: June 22, 2018, 08:25:31 am »
Install a passive repeater.  Place a phone band antenna on the roof and connect it to another phone band antenna inside the room through coaxial cable.
But, that's the rub.  900 MHz, or even worse, 2.4 GHz requires some really GOOD coax!  The system I saw had some roughly 1" diameter semi-rigid coax that was likely pretty expensive.  But, it DID work!

Jon
 

Offline CopperCone

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #12 on: June 22, 2018, 08:26:25 am »
a directional to omni converter is new to me, it reminds me of a disco ball stimulated by a laser, or those high end solar panel optics
 

Offline thermistor-guy

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #13 on: June 22, 2018, 10:35:14 am »
Install a passive repeater.  Place a phone band antenna on the roof and connect it to another phone band antenna inside the room through coaxial cable.
But, that's the rub.  900 MHz, or even worse, 2.4 GHz requires some really GOOD coax!...

Jon

or a G-Line (single-wire transmission line), which apparently has lower loss than coax.
 

Offline David Hess

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #14 on: June 22, 2018, 10:36:14 am »
Install a passive repeater.  Place a phone band antenna on the roof and connect it to another phone band antenna inside the room through coaxial cable.

But, that's the rub.  900 MHz, or even worse, 2.4 GHz requires some really GOOD coax!  The system I saw had some roughly 1" diameter semi-rigid coax that was likely pretty expensive.  But, it DID work!

If a directional antenna is used on the roof, then its gain makes up for some of the coaxial cable loss.  An RG-8 sized cable like LMR400 is not too large for convenience or too lossy.
 

Offline Lord of nothing

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #15 on: June 30, 2018, 08:15:45 am »
Call your Operator and order an Active Repeater!
Why is that legal? Thats simple because the amply fie only your Operator Frequency.
Made in Japan, destroyed in Sulz im Wienerwald.
 

Offline Karlo_Moharic

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #16 on: June 30, 2018, 09:54:49 am »
Buy GSM amplifier , it's around 30$ on ebay and comes with receiving antenna that can be put on the outside
 

Offline NiHaoMike

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #17 on: June 30, 2018, 02:01:30 pm »
Do they provide Wifi that allows the connection of personal devices?
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Online Circlotron

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #18 on: June 30, 2018, 03:16:05 pm »
Do they provide Wifi that allows the connection of personal devices?
Yes, and iMessage and FaceTime is usually quite okay. Sending SMS to Android users is a problem. And normal phone calls to them also.
 

Offline johnkenyon

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #19 on: June 30, 2018, 08:13:42 pm »
If this is having an impact on your ability to do your job, then speak to/lean on your employer and get them to speak to their mobile service provider and get a femtocell installed.

Of course this only works if you are permanent staff.

Otherwise speak to your mobile provider and see if they have some kind of "Home zone" femtocell offering that you can plug into a network somewhere in your cage (rather than at home...)

/john
 

Offline Lord of nothing

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #20 on: June 30, 2018, 11:06:51 pm »
Quote
Buy GSM amplifier , it's around 30$ on ebay and comes with receiving antenna that can be put on the outside
Its illegal in the most country.
Quote
Otherwise speak to your mobile provider and see if they have some kind of "Home zone" femtocell offering
never heard that any European Company give it to customer. I head in Germany one was offer then for a very hight Price.  :scared:
Made in Japan, destroyed in Sulz im Wienerwald.
 

Offline NiHaoMike

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #21 on: July 01, 2018, 08:57:07 am »
Do they provide Wifi that allows the connection of personal devices?
Yes, and iMessage and FaceTime is usually quite okay. Sending SMS to Android users is a problem. And normal phone calls to them also.
Google Hangouts handles texts and voice calls over IP.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline CopperCone

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #22 on: July 01, 2018, 11:35:56 am »
How much signal will a wire carry?

I am asking because I own a USB isolator that does not isolate the power (it uses fiber link), so I can drill out the power wires with a fine drill, but there will be still a wire in the vicinity. How much energy can something like that couple from a computer to a SDR or other USB device?

I would drill it out on both ends so its just a floating bit of conductor between the two USB ports. or I might sell the thing because it irritates me now that I got this thread in my head.
 

Offline FlyingHacker

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #23 on: July 02, 2018, 02:10:05 pm »
Sounds like you have an iPhone. Did you try enabling WiFi Calling? Don’t know if that works where you are, but here I can make and receive normal cell calls that are actually us8ngmy WiFi instead of the cellular connection.
--73
 

Offline wolferl1210

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Re: Passive longwire cellphone antenna to inside dead area?
« Reply #24 on: July 02, 2018, 03:57:32 pm »
A wire will do nothing at all for mobile phones. Stories about 'reflectors' or two
antennas, one inside, one outside, connected by a cable are wasting money.

The only solution - and I did several installation of this - will be a GSM repeater.
But before you invest you have to check two things:

- what system you want to extend: GSM, UMTS, LTE ? You need a repeater that
will handle the transmision mode & frequency of your mobile phone provider.

You did not say in what country you live. Yes, you find some on ebay, but:

- A GSM repeater (or UMTS, LTE) is a receiver with an antenna outside and an
transmitter + antenna inside. And in most countries 'transmitter' need a license
or an approval. Or, in some countries, they simply don't care...

Good luck!
 
 


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