Cell site question

Hi everyone!!

I'm courios about some cell site towers where net-like flat sheets can
be seen to the sides of some antennas (panels). Anybody know what is
the purpose of this sheets surrounding a panel?

I'm writing from Colombia (South America), any comment will be really
appreciated.

Maybe it works like a reflector to make the antenna more directional or
like a screen to limit the radiation to the rear or side.

webcar2001@hotmail.com wrote:
> Hi everyone!!
>
> I'm courios about some cell site towers where net-like flat sheets can
> be seen to the sides of some antennas (panels). Anybody know what is
> the purpose of this sheets surrounding a panel?
>
> I'm writing from Colombia (South America), any comment will be really
> appreciated.
>

--
Frank Harris in San Francisco with an A680

They are sheilds to make the antenna more directional.

<webcar2001@hotmail.com> wrote in message
news:1119830446.358203.163650@o13g2000cwo.googlegroups.com...
> Hi everyone!!
>
> I'm courios about some cell site towers where net-like flat sheets can
> be seen to the sides of some antennas (panels). Anybody know what is
> the purpose of this sheets surrounding a panel?
>
> I'm writing from Colombia (South America), any comment will be really
> appreciated.
>

"Frank Harris" <frankbhX@XcompuserveX.com> wrote in message
news:OL4we.510$j04.256@newssvr21.news.prodigy.com...
> Maybe it works like a reflector to make the antenna more directional or
> like a screen to limit the radiation to the rear or side.

Exactly!

>
> webcar2001@hotmail.com wrote:
>> Hi everyone!!
>>
>> I'm courios about some cell site towers where net-like flat sheets can
>> be seen to the sides of some antennas (panels). Anybody know what is
>> the purpose of this sheets surrounding a panel?
>>
>> I'm writing from Colombia (South America), any comment will be really
>> appreciated.
>>
>
> --
> Frank Harris in San Francisco with an A680

"John S." wrote:
>
> They are sheilds to make the antenna more directional.

Why would you want a directional antenna?

Notan

Notan wrote:
> "John S." wrote:
>
>>They are sheilds to make the antenna more directional.
>
> Why would you want a directional antenna?

They want a given cell site to cover a particular area, to maximize call
capacity. With GSM systems, the issue is frequency re-use. With CDMA
systems, everyone is on the same frequency, so you want to minimize the
noise (that is, calls other than your own) in a particular location, but
not have holes with no coverage.

CharlesH wrote:
>
> Notan wrote:
> > "John S." wrote:
> >
> >>They are sheilds to make the antenna more directional.
> >
> > Why would you want a directional antenna?
>
> They want a given cell site to cover a particular area, to maximize call
> capacity. With GSM systems, the issue is frequency re-use. With CDMA
> systems, everyone is on the same frequency, so you want to minimize the
> noise (that is, calls other than your own) in a particular location, but
> not have holes with no coverage.

Wouldn't "not have holes with no coverage" suggest an omni-directional
antenna?

Notan

Notan wrote:
> CharlesH wrote:
>
>>Notan wrote:
>>
>>>"John S." wrote:
>>>
>>>>They are sheilds to make the antenna more directional.
>>>
>>>Why would you want a directional antenna?
>>
>>They want a given cell site to cover a particular area, to maximize call
>>capacity. With GSM systems, the issue is frequency re-use. With CDMA
>>systems, everyone is on the same frequency, so you want to minimize the
>>noise (that is, calls other than your own) in a particular location, but
>>not have holes with no coverage.
>
> Wouldn't "not have holes with no coverage" suggest an omni-directional
> antenna?

A lot of times they are trying to fill in specific gaps caused by hills,
valleys, large buildings, and so on. If the coverage area were just a
nice big perfectly flat area, it would be easy.

"Notan" <notan@ddress.com> wrote in message
news:42C7EC0C.5C808619@ddress.com...
> "John S." wrote:
>>
>> They are sheilds to make the antenna more directional.
>
> Why would you want a directional antenna?

Cellular is a "directional" type of service. In order to re-use the same
frequency in a nother cell the antennas are directional. That is why you
will typically see 6 antennas (2 per sector/3 sectors) on a cell site. At
thimes you will see 3 per sector and occasionally more.

More than 3 per sector typically means that they still have TDMA and AMPS
which they have moved to another antenna.

CDMA usually has 2 antennas per sector.

"Notan" <notan@ddress.com> wrote in message
news:42C87816.234E391E@ddress.com...
> CharlesH wrote:

>> They want a given cell site to cover a particular area, to maximize call
>> capacity. With GSM systems, the issue is frequency re-use. With CDMA
>> systems, everyone is on the same frequency, so you want to minimize the
>> noise (that is, calls other than your own) in a particular location, but
>> not have holes with no coverage.
>
> Wouldn't "not have holes with no coverage" suggest an omni-directional
> antenna?

But then the Omni wouldn't allow re-use of that fequency at adjacent cells.
Cellular was designed with directional antennas in mind.