Tree Height Loss

I am new with Fixed Wireless. I am extending the school internet to a low income around the school building. the tree height in the needed direction is at the same height as the antenna. i anm going to use the b5 and acx. my maximum range is 2000 feet. The trees are maple and at most two deep. how much loss can i expect or can i get signal on he other side of the trees to permit more back haul and micropops. the tree tops are at 260 and the antenna is about 255. ground is about 195.

Shooting through trees will kill your signal, it’s hard to predict exactly how much though. You can get a bit of prediction from the Mimosa Design tool, there is an option in the PTMP settings to simulate foliage eating up your signal. That said, it’s nearly impossible to give an accurate prediction even with the information that you have supplied already. I would guesstimate 20-30 dB of loss, but depending on location that will vary wildly.

You one advantage is that you are using a fairly hi gain antenna with the B5, the A5x (I am assuming that is what you are using) you will want to use a high gain antenna as well as hi gain antennas on your Customer Premise Equipment. The high gain antennas will help with picking up the weak signals some, but not a lot. Another issue is that alignment will be a massive bugger, the trees can effect the different chains (Horizontal and Vertical or H/V) differently, heck just the difference in the location of where your H/V are on the antenna will mean differences in how the signal is effected. (BTW, H/V chain mismatch will negatively effect the speeds your antenna can Transmit/Recieve at, you mostly want < 5 dB difference between your chains)

Too be honest, I would look for any way you can avoid the trees as much as you can. One option could be 60 GHz equipment. There isn’t a lot of it, but Mikrotik has pretty small access points and CPE equipment that could give you some more flexibility for getting people connected.

if 5Ghz has great loss due to tree blockage wouldnt 60Ghz be worse.

Hi @isaac2,

The higher you go in frequency, the more loss you’ll see with obstructions (like trees). The inverse happens when you go lower in frequency. This is why radio stations and analog TV stations could transmit so well (along with being really high power).

Another example is TVWS and 900MHz being able to transmit through trees so well.

But as you drop down in frequency, the less bandwidth you can transmit. So essentially if you’re doing NLOS links, you’ll have lower throughput than if you were doing LOS links.

I think I might have a podcast talking about this exact topic… it’s been awhile - done a lot of them!

where do i find the podcast. we get some LOS through the openings between trees and NLOS is anticipated. We are going to mount the A5 with N5-360 and make measurements. this is a non profit attempt to provide internet to low income students resdences by the town and school. American Tower waived pole space cost at 70- feet.

Can you see the your target at all or is it completely covered? Maples are not the worst to shoot through but 2000 feet of them would be pushing it. If you can keep your shot under the canopy of the trees and more “in the trunk lower branches”. I have done this successfully with taller Maples and Oaks --but not at 2000 feet. (Not implying I have tried that and failed, just that I have never done it at that range). I have done what you are describing at 1350 feet with C5x (20 dbi dish) and getting -55 to -65 on the low side after rain or its just wet out. Part of the issue on advice is actually ‘seeing’ what you are seeing.

Also keep in mind fresnel zone will be around 9 feet so keep that in mind and keep it out of the dirt if you shoot low.

To Williams5 point the B5 has good gain if you can find a break or thinner gap in the trees you may be able to squeak through with hardwoods under the canopy.

Mind you if there are any pines along the route all bets are off as pine trees just suck RF out of the air with their needles being so close to the wavelength

good luck!

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I meant to use the Mikrotik 60 GHz equipment as a, possibly, more flexible option for connecting up clients. Physically smaller AP/Client device means you can use a smaller mount and have more options available to you for mounting. Instead of trying to shoot through the trees you can go for shooting around the trees when you can. A side benefit of 60 GHz is that the link bandwidth is huge, so you might be able to get creative with bouncing links from building to building. Yes, 60 GHz will get blocked by a wet piece of paper and shooting long distance links isn’t really an option, but for not a ton of money you can get something that can shoot 2000 ft pretty easily and has a tiny frenzel zone to work with.

its only one big maple tree blocking LOS. not 2000 feet.
I will be taking video tomorrow. we intend to install a A5 and measure to start. hopefully we will get more coverage than the Google Earth viewshed. i will record the view and could send the Google Earth neighborhood view.

isaac

thanks William. we are going to test form school roof top with A5 and see what we get. there are lots of maplewood and few high roofs.

william are you a mimosa employee. because until now i never spoke to any.

Nope, just a smuck who hangs out on the forums WAY too much. I was helped out a bit and I figured after I spent so much time fixing my own problems with Mimosa (largely products of my own faults/bad habbits) I would help other people out.

@DustinS is a Mimosa employee though, he is even on their podcast!

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i appreciate your advice and welcome the sharing of experience by other users.

my project is not for profit and to get low income students on line and have what my kids take for granted…

stay safe.

If its just a single big fat maple I think you will be okay. This is the perfect time of year to do your test as the signal result will\should be at the lower end of the curve due to the nature of the tree sucking up water being springtime. Try to keep your strength on your chains to within 2 dbm of each other. So you may have to test and move a few times but it is worth it.
image

This is the actual reading right now of the shot i’m doing through a stand of (tall) maples and oaks around 1300 ftish… Just to be clear these trees are around 80 - 100 feet tall and I mounted the C5x’s on Maxwave rooftop stands in the woods. Height of the radio is at 13 feet on each side. I am mostly going through trunks and minimal foliage as the canopy is much higher up, even with the upper side of the fresenel zone.

In the fall signal will go up to -49 and hold there until this time of year (spring). Unless everything gets coated in ice, then it drops to about the current reading until all the ice\snow evaporates off. Worst i’ve seen is -65 when it rains very heavy but it doesn’t hold long and will float -58 to -60

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@Shannon1, what antennas are you using for your C5x?

n5 x20

isaac fajerman

20 dbi dish. I did buy the 25’s but already had the 20’s on the radios so I used those to test as a start… To which went to going live shortly after.

so if i take the worst case signal minus noise and get better 10db i should be good. look up google earth 274 Boyden Ave, Maplewood, NJ 07040
and pan around the roof top.

I’m assuming the school is the headend? What direction is your destination?