ICE, 900 omni and sector antennas, surge suppressors, 5.8

Hi all hope you’re doing well. I thought I would give my 2 cent’s on a few things and maybe save some of you some trouble.

900AP’s with omni antenna. We don’t have many choices when it comes to Horizontal polerized omni antennas, but here are a few things to consider.

1. Make sure the antenna circuit is grounded properly. Some manufactures ground them internally to the metel housing if not you should do it externally. An ungrounded omni antenna under proper conditions can act as a large capacitor, build up a charge and discharge into the AP damaging the radio. You will see the AP’s performance degrade over time. We have been installing a small gas discharge surge supressor between the AP and antenna for protection. You can ground the unit to the tower.

2. If you think that the possability of you’re 900AP having more then about 50 SM’s on it Don’t use an omni unless you are in an extremely low noise environment. It’s understandable if you can’t afford to at first. The omni will catch interfearance from every direction. With a low number of sm’s you won’t see an issue, but when it get’s loaded you will start to see issues. re-reg’s will start to climb.

Example: Over the past year or two I have watched several 900 POP’s. Some in and around Roswell (yes I know alians), and EL Paso, TX. EL Paso is an extremely noisy environment with Juarez, Mexico accross the river and virtually no FCC regulations on that side. Switching to 3 120 deg or 4 90 deg antenna’s increased performance, and re-reg’s dropped. 6 integrated AP’s would be ideal, but if you only have the possability of 200 or 300 customers on that POP you might not want to do that. If you don’t have to rub the site at full power due to distance you can use 3 120 deg antennas, and a 3 port power divider with a single AP. When the site gets up to about 50 SM’s you can simply just remove the divider and add an AP or two. The power divider will induce loss in the system so find one with as little loss as you can.

3. We have been using some 120 deg 900 horizontal pol antennas from MTI. They work well but two things to think about. They have a metel housing and back plate. Make sure you use a surge supressor between the AP and the antenna. If the tower gets hit by lightning with no supressor not only will you loose the antenna but you will also loose the AP, and if you don’t have a data line supressor between the AP and CMM you will loose it too. Keep in mind that a direct hit will take out all equipment regardless.

4. ICE. I have 3 900 POP’s at 10,000 ft or above. For the last 2 years I have used integrated 900 AP’s and the sites have SM counts from 10 to 50. between the sites if I could use connectorized AP’s I could recover several for new sites so this summer I made the move. Wrong move. Those sites get snowed in all winter. The integrated unit’s produce enough heat to keep ice from building up on the antenna. We have already had several snow storms this winter at those sites and the ice on the 120 deg antennas has decreased performance enough for me to switch back.

5. MTI produces the dual polerized 5.8ghz antennas that come on the 30, 60, 150, 300 ofdm Orthogon/Motorola radios. We just got some in from Teletronics. The regular antenna comes with a mount identical to the original 1st generation mount on the ofdm radios, and it has 2 N female connector’s. You can also get it with a housing similar to the ofdm’s. This antenna has 2 SMA female conn this is the version on the ofdm units. I had a spare set of conn 150’s but needed integrated ones. Pulled the cover off and installed the antenna. The reason I ordered the unit’s with housing is I can fit 2 5.7 bh’s inside. one horizontal and one vertical for a redundant link. Testing now and will let you know how it goes.

That’s enouph for now. Excuse the spelling.