Hi all,
I am currently running mikrotik in a routed network configuration with my radios located on the towers with 4-10' runs of lmr400 to the antennas. I have a couple of these systems at 600' on one tower and 2 more systems at 280' and 180' on 2 more towers. Tower climbs here are quite expensive not to mention that not many tower crews know anything about wireless radios.

I would like to be able to put my radios on the ground and leave the antennas where they are using heliax or some form of waveguide so the loss wont be so great.

The 600' may have to stay like it is but does anyone have any experience with heliax or any transmission cable with low loss that we could use atleast on the shorter towers. Most of our new installations will be 300' or less.

We have the following wireless configurations:

180' - 3 120 sectors at 2.4, 2-180 sectors at 900, 2 panels at 5.8 for backhaul. 2.4 and 900 serves customers. There is 1 5.8 in the 900 radio on a 532a and 1 5.8 in the 2.4 532a.

280' - 2 180 900 served from different 532a's and 1 5.8 for backhaul.

600' - 2 180 2.4 served from its own 532a, 2- 180 5.8 served from its 532a and soon to be 3 120 900 sectors served from their own 532a. There is approximtely 20' of seperation on each of these systems.

I realize I could put amps at the radios to overcome the loss issue but they create their own problems.

My other question is by using heliax, could I then put the 3 900mhz sectors into a combiner into the heliax and run only 1 frequency to achieve 360 degree coverage without affecting service.

Any help would be greatly appreciated.

thank you
Kenny

kenny,

如何are your 600ft installs set up now? I'm assuming 48v PoE? 600ft is a LONG run.

in case ur not aware, according to timesmicrowave.com:


Not pretty for a long run like that... how are you 600ft up btw?? thats highest tower in south US i've heard of..[/quote]

I put a a/c power box at the 600' level and am running 48v poe to the 532's that are up there now from that power box. That creates a problem in itself meaning that if I have to power cycle 1 532 then they all have to get power cycled. Not good, fortunately that does not happen very often.

Coverage at 2.4 is about 4 miles wifi from a laptop with external antenna. Of course there are dead spots in some parts of town.

Ptmp links we have some at 10 miles that are 4-6mb one direction. This is all from cm9 cards with 180 sectors.

I was looking at the lmr600 and 1200 but the loss at 5.8 is prohibitave for the 600' run.

I was thinking more along the lines of 1/2 or 7/8 heliax. I was playing with link calculations on a site that was recommended on this board and it looks like the 7/8 might be the way to go on the 600' but I dont know what the 2 antennas on the same freq will do. If I seperate them vertically by about 20' it may do ok but not real sure yet.

That 600' is the highest in my area but there is a guy about 100 miles west of me at 1200. But he has an elevator on his tower so he does all his work himself.

The bad part about the heliax is the material and the cost of hanging it is going to be 2-3 times in cost of what the radio and antennas cost. However one radio replacement could be as much as 1000 dollars in my area not to mention just getting a tower crew to get to it. That could take a couple days.

Looks like I can either pay up front with the expense of heliax or on the back side with tower climbing costs. Just looking at the options to see if it will be worth it.

with 7/8 helix you will still be looking at 20db of loss @ 5ghz for 600ft run...just for cable run

is this still do-able?

sorry to get off topic, but are you splicing 3 RB532s into one 48V PoE feed?? what kind of Power supply is it?

无论如何它年代真正的昂贵的y good coax run

tks

20db is pushing it. The 5.8 may have to be left alone.

As for the power supplies, the ac runs to a power strip on the tower and individual power supplies are plugged in. Not ideal but it has worked for 2 years with the occasional power cycle.

We were using locustworld mesh up there so it was not a problem but with 3 different systems it could get messy.

We do run redundant wireless links so we should always have a path to our internet feed.

I am going to do more research on the cable question and more calculations to see if it will work. So far the 5.8 does not look promising.

kenny

I was thinking more along the lines of 1/2 or 7/8 heliax. I was playing with link calculations on a site that was recommended on this board and it looks like the 7/8 might be the way to go on the 600' but I dont know what the 2 antennas on the same freq will do. If I seperate them vertically by about 20' it may do ok but not real sure yet.

A couple of thoughts...

7/8 Heliax isn't rated up to 6GHz, IIRC. Really strange RF things happen on perfectly good LDF5-50 and larger heliax feeders. One would have to understand the physics of it to really explain well, but it just doesn't work. 2.4GHz is just fine on large Heliax though.

600' isn't something that I'd try without a bidirectional masthead amp.

Ever thought of using something like this:

http://www.infomicro.ca/login/detail.asp?idnum=321

So you'll need to do this right once
I have six 100-200m towers working and if setup is made correctly there's no need to change anything.

Never use an amp, unless you dont like the customers (hehe) but umm whichever way you look at it your gonna spend a good deal if you intend on running coax up 600ft. And also your gonna have to have a REALLY BIG ANTENNA to make up for the signal lost.

In any situation its always best to place the ap near the antenna. So I would recommend getting a high guage wire and run about 60 V at 120 Watts and use a "mini switch" at the 300ft mark and run poe up the remaing 300ft to your routerboard.

The aformentioned power might be a bit low, but you can improvise.

Of course its more work as opposed to just running the coax up, but hey it would prove itself as being 800% better as you wont sacrifice signal quality, etc.

Regards.