Omnidirectional and Directional Antennas

04-01-2002

Hi there,

here in Europe we are restricted to 100 mW (=20 dBm) ERP. So I have the following question.

When I combine two 15 dBm cards with 7 dBm omnis, do I get the same range as with two 7 dBm directional antennas (if we neglect the higher noise floor I get with the omnis)?

04-01-2002

im not sure exactly what your tring to do, but
you cant simply just use more then 1 antenna on the
same system because of phaze.

04-01-2002

No, I am not trying to add 2 antennas to one system. The setup is the following:

1 card (15 dBm) with one external antenna (7 dB) sending to another card (15 dBm) with nother antenna (7 dB).

The question:

Does it make a difference for the reachable distance wether I use omnidorectional antennas of directional antennas?

04-01-2002

That will work very well! You should see a big jump in signal.

Cheers,
Thorn

04-01-2002

In theory, the antennas will give you the same gain. Yes there will be more noise recieved with the omni's due to the 360 deg pattern. One note however: vertical beam on the 7dbm omni will be around 10-15 degrees (or less!). On the directional it should be 30-50 degrees. This will make it harder to align the narrower beam on the omni's. They will have to be at the same height, or if at differing heights, they will have to be tilted to get their narrow beams to line up. I would choose the directional antennas over the omni's.

04-02-2002

Thanks, that was exactly the information I was looking for.

04-01-2002	#1 (permalink)
Posts: n/a	Omnidirectional and Directional Antennas Hi there, here in Europe we are restricted to 100 mW (=20 dBm) ERP. So I have the following question. When I combine two 15 dBm cards with 7 dBm omnis, do I get the same range as with two 7 dBm directional antennas (if we neglect the higher noise floor I get with the omnis)?

04-01-2002	#5 (permalink)
Posts: n/a	7dbm omni vs directional In theory, the antennas will give you the same gain. Yes there will be more noise recieved with the omni's due to the 360 deg pattern. One note however: vertical beam on the 7dbm omni will be around 10-15 degrees (or less!). On the directional it should be 30-50 degrees. This will make it harder to align the narrower beam on the omni's. They will have to be at the same height, or if at differing heights, they will have to be tilted to get their narrow beams to line up. I would choose the directional antennas over the omni's.

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04-01-2002	#2 (permalink)
Posts: n/a	im not sure exactly what your tring to do, but you cant simply just use more then 1 antenna on the same system because of phaze.

04-01-2002	#3 (permalink)
Posts: n/a	No, I am not trying to add 2 antennas to one system. The setup is the following: 1 card (15 dBm) with one external antenna (7 dB) sending to another card (15 dBm) with nother antenna (7 dB). The question: Does it make a difference for the reachable distance wether I use omnidorectional antennas of directional antennas?

04-01-2002	#4 (permalink)
Posts: n/a	That will work very well! You should see a big jump in signal. Cheers, Thorn

04-02-2002	#6 (permalink)
Posts: n/a	Thanks, that was exactly the information I was looking for.