Closest two JRMA0-680-10/11 antenna can be for B11-L + B11-H


#1

I am planning to deploy a B11-H and B11-L on the same pole with a Jirous JRMA0-680-10/11 for each. How much separation do I need between the antenna?

Link distance is only 1.5mi/2.5km. I will have the full spectrum available to me on both and plan to use the widest channel possible for the highest rate point-to-point.

Thanks – lee


#2

How much frequency and angular separation do you have between these two links?


#3

I would like to mount 2 radios on a single 10ft pole, both on 11GHz, both using the dual-beam 80MHz.

If I’m understanding this all correctly (and that’s highly doubtful) I can get one radio on the low end of 11GHz and the other radio on the high end of 11GHz so they don’t interfere with each other.

So I guess the angular separation is that they are in parallel?


#4

Just trying to get an understanding on what you’re attempting to do, so you want two B11 radio and antenna sets on the same path? Ie. they are both going to the same location? I think the problem that you’ll run into is with the licensing and coordination of the frequencies. In the 11Ghz band(at least in the US, which I’m just assuming, may be different where you are, you’ll have to check with your local agency), there is a frequency coordination and licensing process that will more or less determine which frequencies you can use and finding the amount of bandwidth to license for two B11’s at 80Mhz on the same path may prove difficult.


#5

Yes, sorry for my lack of correct terminology. Yes I want 2 radios on the same path, so I can OSPF load balance over them for performance and redundancy (that’s the easy bit).
I have no competition for this, licensing wise. I’m in a valley in a very rural area. I have the entire spectrum available.


#6

There’s no real reason why it shouldn’t work, just inform your frequency coordinator(Liz at Intelpath is great to work with) what you are doing and they’ll find the frequencies to assign to you for both paths. Email her with your design plans, heights and path coordinates and they’ll provide a quote for handling the licensing and checking frequency availability.


#7

I would also be concerned over what size diameter pole (and pole thickness) that you will be using to mount these dishes on? Especially if you are in an area that you might have heavy winds in?

I would at least go with a 4 inch diameter pole, very heavy thickness. If you can attach something to the outside of the dishes that can go to some other support structure to help eliminate wind sway, that would also help your stability !


#8

Is there a reason you insist on 11ghz for such a short link? 18 or 23ghz would be a better fit for licensed. A 24ghz(unlicensed)product would be a good fit for your second set of radios. An E-band product would give you better throughput. If we knew more about your application of the products we could give you better advice.


#9

We’re planning on using a short Rohn 55G tower.


#10

My reasons for going with 11GHz?

Rain & Fog – I’ve been told 24GHz will have trouble with the environment by my local WISP. My limited research indicates the higher the frequency the worse the attenuation gets. Last I looked the 70GHz+ range had very limited distance capabilities, although the bandwidth was higher. Fog can get under 3ft visibility, rain probably worst case is 1-2inch/hr. Winds max about 85mph.

Other frequencies – I’m avoiding anything unlicensed because I’ve had problems in the past with interference.

Application – I want to get a full gigabit bidirectionally (ie 2gb/s aggregate), with redundancy (so two radios)


#11

Even though you are going to use a tower, I would put 2 horizontal poles across the tower, using “Cross” brackets. About 5 feet height between the upper and lower one. Then install a 4 inch pipe vertical on the 2 poles using “cross” brackets. Mount the dish to this 4 inch pipe.

This puts the wind load and torque on the tower across 2 tower legs, instead of it trying to twist one of them.

I would then run a small pipe/piece of electrical conduit from the outer edge of the dish (Usually bolt holes there), back to the third leg of the tower. This will then eliminate any wind twist of the dish (But will not eliminate any twist of the actual tower)

We have had medium size dishes actually twist off a tower leg, when they were mounted on just one leg !


#12

I’m going to instruct the engineer to align two legs to point roughly toward the other side, so we can keep the angle close to 90 degrees, although I doubt that matters much,

Would you use schedule 40 or 80 for the vertical piece?

That was my fear with using a 2 inch pole, that it would twist the pole rather than snap it.

We’ll also be rigging the tower itself to reduce/prevent twist.


#13

Schedule 40 at 4 inch diameter would be fine!