Generally a omni send signal straight out and a high gain omni might only have 5 to 6 degree vertical beam width. So only 2.5 to 3 deg is aim down. A lower gain antenna will have wider beam width. But then you also have quality antennas with electronic downtilt on them so say a high gain antenna with 7deg beam (typical on a 12dB omni) you have 3 degree electronic downtil (also typical value) only 0.5 degrees of the signal is sent above horizon line.
A 15dB omni might only have about 5 deg beam and if you have no electronic downtilt it becomes useless on taller structures. Unless your clients are only far out (depending on hight might have to be very far out). You can play with my down tilt calculator. http://www.wisp-router.com/calculators/downtilt.php You do not want to have customers closer then the inner -3dB radius and most of them should be close to the sweet spot and of course they should not be outside outer -3dB (with omni generally no risk unless your providing internet to aliens. ;) ) /Eje Sent via BlackBerry from T-Mobile -----Original Message----- From: RickG <[email protected]> Date: Mon, 23 Feb 2009 00:23:55 To: WISPA General List<[email protected]> Subject: Re: [WISPA] tower issue Marlon, I was thinking about what you said about high gain omni antennas sending more signal UP. With respect to direction, what's the difference between between a high gain unit and a lower gain unit? -RickG On Sun, Feb 22, 2009 at 10:34 PM, Marlon K. Schafer <[email protected]>wrote: > Not sure if it's related or not, but high gain omni antennas are usually a > great big no no. They tend to send more signal UP than in the direction of > the customers. > > I'd replace it with an 8 or 9 db unit just on principal. You'll probably > find that most customers will actually get a BETTER signal. > > laters, > marlon > > ----- Original Message ----- > From: "RickG" <[email protected]> > To: "WISPA General List" <[email protected]> > Sent: Sunday, February 22, 2009 7:23 PM > Subject: [WISPA] tower issue > > > > OK, here a good one! (aka, how I spent my weekend in a blizzard!) > > > > One of my towers has a single WARP/StarOS connected to a 5GHz grid for > > backhaul and a 15dBi omni for the local connections. > > On Saturday, after making some small changes, I rebooted it and it would > > not > > allow me to connect via wireless any longer - or my customers :( > > So, I go to the tower, connect up via ethernet and everything is a usual > > but > > I see all associations but only a few client have ip addresses. I can > ping > > the few clients but the packet loss is huge 80-90%. I then reload my > > backup > > but still get the same thing. I try changing channels, but still the > same. > > I > > then systematically begin replacing parts starting with the radio card. > > Eventually, I replaced EVERYTHING but still have the problem. One note: > > occasionally, twice of maybe three times, after a reboot, all came back > > normal. The third time, I left well enough alone for now but of course, > > you > > know what will happen the next time I reboot. > > > > Any ideas??? > > > > -RickG > > > > > > > -------------------------------------------------------------------------------- > > WISPA Wants You! Join today! > > http://signup.wispa.org/ > > > -------------------------------------------------------------------------------- > > > > WISPA Wireless List: [email protected] > > > > Subscribe/Unsubscribe: > > http://lists.wispa.org/mailman/listinfo/wireless > > > > Archives: http://lists.wispa.org/pipermail/wireless/ > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
