diversity antennas

[esteban]

We are using Cisco Aironet 350 for our WISP. My question is about the ability of this AP to handle 2 antennas.

Does the 100mw power is divided for each one of the antennas or does each one have 100mw output power ?

Can you use repeater mode using only one antenna ?

Can I use a Patch panel antenna on each conector pointing to a diferent direction to get a better coverage ?

Can I use a convination of patch panel and parabolic grid antennas to repeat a far a way signal into a specific area ?

What's the difference between parabolic and yaggy antennas ? Can I use a big parabolic antennas to cover a wide area like with a patch panel antenna ?

What are the best quality antennas in the market ? The best patch panel one ?

How can an amplifier provide a better coverage if my clients still only have very limited power at their side ?

Thankx for your help, hope you get some usefull ideas from this post, :p

Esteban

[wirelessboy]

hey esteban

u are asking for the whole cwne syllabus boy!

WISP Hmmm, are u talking about WLAN(inside a room) or MetroLAN(campus coverage or even higher distances).
please clarify, what are the hop distances, and what BW are u looking at.

okay but first the answer to first question, the POWER is NOT DIVIDED equally between two antennas, the primary antenna transmits a power of 10 to 100 Mw power, the secondary antenna is tradionally for RECEIVING only, but please check up with your particular Vendor and Brand.

BIG Parabolic Antennas give u a very SMALL COVERAGE!!!, they are used to drive signals to long distances, SO beware, for WLAN Patch or Panel are always better.

more inputs from u , i can give u a detailed answer.

wirelessboy

[esteban]

:D It started as one simple question but then I made the whole list !!! Thank you a lot for your answer, I guess many people didn't reply because they found so many questions i!

The AP's are rugged cisco 350. I'm providing a small town with Internet service.


Regards,

Esteban

[oshea85]

Wirelessboy is right, the power is not divided. However, the AP listens on both antennae; when it hears a device, it then switches to the receiving antenna that is getting the best signal; this helps greatly with multipath and nulls. When transmitting, the AP will send with the antenna it heard the client with the best signal.

You can use repeater mode with one antenna.

You cannot use two patches pointing in different directions. If the AP TX or RX on one antenna (east, for instance), it cannot detect transmissions to the west. You will get lots of RF collisions and very poor performance. You could, if you found you needed to, put two patches pointing the same way.

Do not mix antenna types.

Look for amps that are TX/RX. They increase the receive gain as well. Otherwise you would need a TX amp on both sides.

[wirelessboy]

hey esteban

Aironet is a very good RF modem, 350 can have varying power levels upto 20 DBm .

Without Amplifier u can get 2 Mbps upto 12 Kms normally. so better do not use a power amplifier.

Proper cable terminations, connectorisation and antenna alignment will do the trick.

If the clients are not visible from naked eye, better to use semi-parabolic antennas, and please do not use AUTO-CHANNEL for cisco aironet.

anymore questions, please reply in Troubleshooting section, all the best.


all the best.

[esteban]

Hello Wirelessboy

yeah, I had a very bad time when I used the auto channel option. Things are much better with the new firmware. I can go much farther away and disconections are gone now. They use to happen very often with prior firmware. I hope they some how make IOS work in the 350. I know the new aironets run IOS.

I never heard of this semi-parabolic antennas, can you point me to a good one ?

Esteban

[rodelcava]

I have 5 Cisco Aironet 350 bridges and I know the diversity no work very good!.

First I installed a 15 dbi omnidirectional on the primary connnector and a 24 dbi grid on the other. I pointed my 24 dbi grid to my cisco repeter 4 miles far. The performance of the network was poor :(.
After that I install a 500 mw amplifier on each connector, and kabum signal excellent!! No more clients down!. So I know that the AP 350 diversity is not like a water comunication system. You imagine the levels will be the same in both sides, but AP are funy, If you have two pannel antennas and you associate a client in the left antenna your right antenna clients lost signal, and viceversa!

You will have the signal strenght something like this:

strenght **************** 50%

strenght **** 21%

strenght ************* 43%

All the time with many variation :( . After you install a bidirectional amplifier on each connector, you'll have a stable strenght and quality.

I use hyperlinktech amplifier and they work really good :). I ask me: why Hyperlink or ydi sale 100 mw ampliffier?, -It's stupid because many AP has 100 mw output power, but not. If you'll want to use 2, 3 or 4 antenna, you will need a signal splitter and a 100 mw amp. with each antenna!!

Remember this: AP connector not are like a balance!

links

www.hyperlinktech.com
www.ydi.com