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 Post subject: Cell Phone Antenna Question
PostPosted: Dec Wed 06, 2017 8:20 am 
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Our relatives on a remote lake get Verizon just fine, but our ATT is spotty. I have to go stand on the dock to check my messages and I still get connected only 50% of the time.

We visit only occasionally so I'm thinking of building a Yagi on the cheap and making a passive coupler. It's for LTE, but how do I know whether to build a 850-900 MHz or 1900 MHz antenna? I know where the tower is (8 miles away). How does one determine which frequencies are used?


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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Thu 07, 2017 4:47 am 
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Joined: Jul Thu 29, 2010 5:35 am
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Location: Simonton, Texas
I wrapped a wire around my phone and connected it to my frequency counter and made a call.

I think it came up in 900 mHz range. It worked on my EIP frequency counter but not on my HP unit.

It is not unusual for different services to be spotty in different paces. In East texas Verizon works

better than ATT but at my house ATT works and Verizon doesn't. There was a company that made cell

a phone booster which was inductively coupled to the cell phone. You installed it in your car.

I think it was Wilson.

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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Thu 07, 2017 7:12 am 
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Excellent, thanks. I was reminded that my frequency counter has a high impedance setting that will display RF at short ranges. I made a call and it registered 826 MHz.


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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Fri 08, 2017 5:41 am 
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It works.

I made an 11 element Yagi calculated at 12.5 dB gain. The driven element is a folded dipole so it's connected to 300 ohm twin lead. At the other end of the twin lead is a duplicate folded dipole.

The cellphone antenna is on the bottom of the phone. When I position it in the second dipole perpendicular to the plane of the dipole, the meter moves up 5 -10 dB. I need to do more testing, as the fluctuations may be due to the nature of cell communications. But it does improve the signal noticeably, which was my goal. Thanks for your input.


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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Fri 08, 2017 6:02 am 
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Joined: Jul Thu 29, 2010 5:35 am
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Location: Simonton, Texas
I am glad I could be helpful as most of the time it is me receiving the help.

I am interested in your Yagi could you post a picture or a diagram?

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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Fri 08, 2017 7:15 am 
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Koby wrote:
I am glad I could be helpful as most of the time it is me receiving the help.

I am interested in your Yagi could you post a picture or a diagram?


It looks very much like the one pictured below, but with 11 thicker elements not 14 thin ones. The picture's complete article is here: http://bcbj.org/antennae/lte_yagi_diy.htm

I used 1/4 in aluminum rod for the parasitic elements, 3/4 in aluminum tubing for the boom. 1/8" copper grounding wire for the driven element folded dipole.

The design came from here: http://www.k7mem.com/Electronic_Noteboo ... i_vhf.html

Image


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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Fri 08, 2017 7:38 am 
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Location: Waterloo, Iowa
OK, this is gonna sound strange, but maybe not to you guys. Some years ago camping in the desert southwest in a remote area was having real trouble connecting to a cell tower at the location. On a hunch I took off my shoes and went barefoot on the slickrock. Got through OK then. Is I was or was I not antenna/ground plane, or just a coincidence? It seemed to work a couple times.


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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Fri 08, 2017 5:52 pm 
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Joined: Jul Thu 29, 2010 5:35 am
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Location: Simonton, Texas
I don't know what you were but that is why antenna stuff is as much art and mystery as it is science.

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 Post subject: Re: Cell Phone Antenna Question
PostPosted: Dec Fri 08, 2017 10:58 pm 
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Koby wrote:
I am interested in your Yagi could you post a picture or a diagram?


Video here: https://www.youtube.com/watch?v=U1Fqzs6 ... e=youtu.be

This example shows 8 dB gain. So far, in the house, typical gain is 5-10 dB. Not bad for passive coupling.


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