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Mobile Phone Yagi Antenna...

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buloi123

New Member
Hello,

Did anybody knows how to make a yagi anenna for mobile phones?
And if posible please include the computations.... Thanks
 

Klaus

New Member
Why would you want to do that? A Yagi antenna is a directional antenna, more useful for fixed locations. Mobile phones move about, a directional antenna would be a nuisance, IMO.
Besides, with the very high frequencies involved a Yagi would be tiny and rather tricky to make, perhaps etch it on a PCB board?
 

buloi123

New Member
Klaus said:
Why would you want to do that? A Yagi antenna is a directional antenna, more useful for fixed locations. Mobile phones move about, a directional antenna would be a nuisance, IMO.
Besides, with the very high frequencies involved a Yagi would be tiny and rather tricky to make, perhaps etch it on a PCB board?

Because in our province, I can't pick any signal from my mobile phone. So I think of building a directional antenna to point it to the cellular site location to get some signal..
 

john1

Active Member
good idea,
but at those frequencies a dish
made from expanded metal might be more effective
and easier to make ...

And of course would make no direct connection to
the phone itself.

see what others say,
Regards, John :)
 

Klaus

New Member
john1 said:
good idea,
but at those frequencies a dish
made from expanded metal might be more effective
and easier to make ...

And of course would make no direct connection to
the phone itself.

see what others say,
Regards, John :)

Very clever idea. The only difficulty would be holding the mobile phone's antenna precisely at the focal plane of the dish as you talk :wink:
 

john1

Active Member
Hi Klaus,

i was thinking of something about maybe ten inches in dia,
very light-weight, sort of a clip-on thing that would
be maybe a fold-up assembly, like those camera flash units.

I don't know the frequencies involved, but i guess that a
ten inch dish would give a reasonable capture.

Also i'm not sure that the Yagi arrangement would act as
a transmitter, it's primarily for reception.
I'm not that well up on RF propagation, but i don't think
the Yagi reflectors would operate in reverse, ie: sending.
But i could be wrong there.

However dishes do work both ways.

Regards, John :)
 

Nigel Goodwin

Super Moderator
Most Helpful Member
john1 said:
Hi Klaus,

i was thinking of something about maybe ten inches in dia,
very light-weight, sort of a clip-on thing that would
be maybe a fold-up assembly, like those camera flash units.

I don't know the frequencies involved, but i guess that a
ten inch dish would give a reasonable capture.

Also i'm not sure that the Yagi arrangement would act as
a transmitter, it's primarily for reception.
I'm not that well up on RF propagation, but i don't think
the Yagi reflectors would operate in reverse, ie: sending.
But i could be wrong there.

Yagi's work fine both ways, it's commonly used as a transmitting aerial.

Problems with dishes is the accuracy required, you're essentially focusing to a point - the dish needs to be accurately built to do so.

One very easy thing he could try, standing the phone on a car roof - see if that helps, it provides a proper ground plane for the whip in the phone. I often used to do that with an old 2M rig to improve reception.
 

buloi123

New Member
Yagi's work fine both ways, it's commonly used as a transmitting aerial.

Problems with dishes is the accuracy required, you're essentially focusing to a point - the dish needs to be accurately built to do so.

One very easy thing he could try, standing the phone on a car roof - see if that helps, it provides a proper ground plane for the whip in the phone. I often used to do that with an old 2M rig to improve reception.

Yah, one of the problem of dishes are accuracy to point to a certain focus.. it's hard to build, that's why I'm thinking of yagi instead of using dish.

What are the materials needed for building such antenna and the computation of each element to match to a certain frequency? I think mobile phones have a frequency of 800Mhz and 1600Mhz.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
buloi123 said:
Yah, one of the problem of dishes are accuracy to point to a certain focus.. it's hard to build, that's why I'm thinking of yagi instead of using dish.

What are the materials needed for building such antenna and the computation of each element to match to a certain frequency? I think mobile phones have a frequency of 800Mhz and 1600Mhz.

A simple google search finds lots about yagi's. Try this page, which includes a java applet . Bear in mind though, yagi's are essentially narrow band.
 

Klaus

New Member
You could also look up log periodic antenna's. They look like yagi's but have usually more elements and all are connected to the feed line, crossed over alternately. The multi channel TV antenna's are often log periodic to get the wider band width.
For the very high frequencies for your mobile, building such a tiny antenna from wires and bits of rod would be a challenge. You could try etching one on a PCB board, once you have calculated the exact dimensions.
Good luck with that one 8)
 

buloi123

New Member
Thanks for the info. Do anybody knows the formula or how to compute the leghts of the elements with respect to the operating frequency?
 

leosedf

New Member
Mobile phone frequencies are:
European: GSM900 (around 961.2MHz) and DCS1800 (from 1800 to 1890MHz)
USA uses also GSM1900 that's why Triple band mobile phones exist.
A Yagi is commonly used on these problems.
Let me find the link:p
You can also use a BiDirectional amplifier to amplify the outcoming and the incoming signal.
And the best: It really works!!
 
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