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Elevation angle with sectors, maximum range

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Elevation angle with sectors, maximum range

I'm curious what those deploying sectors have found their effective distances are?

Consider a deployment site 3,000 ft up with a clear LoS to a valley below, 80 miles wide (aka, San Joaquin Central Valley), using a Rocket M5 and one of these 90 degree 20dbi sector antenna:

If you aim the sector at the middle of the valley, and the elevation angle say 40 miles out from the deployment site, how far "closer" and "further" from 40 miles is expected to get coverage?  5, 10, 15, 20 miles?  Are their any websites which model this information?  Sites such as airLink or HeyWhatsThat are great to check LoS, or in the later's case to plot "viewsheds," but they ask for assumptions, such as "range" which I've no idea.  I'm sure range will be determined some by the elevation angle which is used.

Jason de KG6H

What you want to know is

What you want to know is called a "downtilt coverage radius calculator"

I use Radio Mobile (computer installed version)  some use Radio Mobile Online (Easier to use, but less flexible IMHO) one of the values it reports is the angle to (based on real altitude and curvature of the earth) to/from the transmitter site, if im outside the desired beam angle then i'm too close/far or too low/high an altitude.

Of course if you take the time to put the real antenna characteristics in the model will just plain show you where you will have coverage and where you will not and one can tweak the design.

It can also be solved (at a basic level) with some trig calculating sides and angles but here are a couple calculators that do what you want at the very basic level.

Throwing in your antenna is 3000 feet above the rest of the ground, assuming a 6db vertical bandwidth (I didn't read your spec sheets)  and a downtilt of 3 degrees the first 5 miles will be shadowed, and after that the signal will reach out to the horizon so once you get 5 miles away in theory you should be able to cover anyone who can see the site that has the mesh node.and doesn't have excessive RF loss. It is possible within 5 miles you may have enough RF power and gain to makeup for the antenna loss but you also may not depending how far you are into the nulls of the antenna.

I don't  belive either of these take curvature of the earth into calculation so there are some points (horizon curves) where the signal may be able to travel from the transmitter further but the receiver may be in the blind just as if it were blocked by a hill that you would need to model with real world coverage.

Subnote: 80 miles while it could be "visable" with enough height to get over curvature of the earth is going to be a long and VERY weak link is my guess, one or both side will have to have a high gain dish on it to make a connection. This is where REAL RF Signal level modeling is needed as the down tilt calculators only say if your in the sector beamwidth range, not if you have enough power to get to it after losses.

Ultimately if your going to be planning a deployment you should do a TRUE RF model with RadioMobile or similar, it will take time (forum threads exist on doing this IIRC) but its going to give you much more meaningful results. 

I basically kept a copy of RM open with a copy of the entire mesh network for San Diego County when I first started looking at sites, I would throw a node down, run a coverage map, and repeat as needed. When I really wanted to know how good a site was I would have it do progressively more precise coverage maps untill I got to my 'final' high quality map that could take a couple hours to run but would be saved to show me every intricate valley and bush blocked area.

K6AH's picture
Ubiquiti Antenna Patterns

Ubiquiti has published antenna patterns compatible with Radio Mobile available for download:

Simply download the corresponding model's ".ant" file and then upload it to Radio Mobile... There's a function on the menu for this.


Great info

Great info, folks.  RF Elements has antenna specs available as well:

Playing with Radio Mobile Online now.

Help with Radio Mobile Online

I can't seem to get it to show proper maps.  I imported both Ubiquiti and RF Elements 20db 90deg sectors antennas (V & H).  When I try to plot a map, it asks for azimuth, so which I'm setting to 60deg.  I shouldn't be seeing any signal anything north of 15degrees and below 105degrees, yet I am.  Even selecting a yagi, I am seeing this same pattern.  It's as if it is ignoring the antenna selection and just using the built-in omni antenna, or I am just flubbing the settings.  The RocketM5 specs shows max TX power at 27dBm, which the charts show is 500mW, or .5W in the notation Radio Mobile Online is expecting.

Here are the coverage settings I'm using:
Antenna Height 15m
Type: AM-5G20-90-Hpol
Azimuth: 60
Tilt: 3
Gain 20dBi

Mobile Antenna Height: 10m
Gain: 16dBI

Frequency: 5850
Tx power (Watts): 0.5
Tx line loss (dB): 0.5
Rx line loss (dB): 0.5
Rx threshold (muV): 0.5
Requires reliability (%): 70

Strong Signal Margin (dB): 10
Maximum range (km): 150

Even if I use the NSM5 antenna (60 degree sector) and change the gain to matching matching 16dBi, I am seeing about 50% more coverage outside of the sector than I think I should be seeing.

Just because it's a sector

Just because it's a sector doesn't mean coverage disappears instantly at the 90 degree mark, that is just the point (with Ubiquiti) that the antenna has 6dbm less gain than the peak gain at center.  Depending on antenna signal can continue for a while to the sides and back. I know of a nanostation that made a (unreliable and poor quality) link 20 miles off the back to a dual polarity omni (this is the exception not the rule for coverage)

After that it looks like sensitive is much too low (.5 uv is -113dbm). Try something closer to 3.5-4uv. That alone should take off some significant distance.

K6AH's picture

Positive tilt is above the horizon, negative is below. 

WL7COO's picture
Try leaving the Azimuth at 0 degrees - when Radio Mobile

Online calculates a link I *think* I saw that  it uses the direction(s) between the the two identified sites as the azimuth and correctly shows the bearings in whatever it's default coordinate system is.  (Wonder which coordinate system that is and if/where we can change it?)

My next bits of Radio Mobile Online familiarization are  to learn whether RM Online will permit:
1.) Modifying the permitted Amateur Freq ranges to be 'Nationalized' to coincide with US Part 97 Authorizations.
2.) Modifying one of the existing 'Antenna Types' to match any specific Antenna or support input of new Antenna Types.

I ordered a pair each of the NSM2 and NSM2 Locos.  Next step is reaching out to Ebay sellers to see who will confirm their Rocket M5s are XM and locating a pair of Rocket M3 (3.4 - 3.7 variety).  

For test, site eval, demo and future deployment use I'm hoping MAARO can assemble and test pairs of Rockets with a sector and an Omni in each Freq Band to ground truth the RM Online & other prediction apps.  Real World data on useful link distances and quality in Urban - Rural interfaces areas probably varies dramatically with micro-RF climates.  While Rocket level power may be more than we actually need initially for our 6 to 8 mile hops,  deploying broader Sector anntenas and having available a variety of deployable higher power gear feels like the way to proceed.

Also, & this definitely needs to be confirmed - I *think* I saw advice on that we should use 0.07muV vs 0.05 for RX Threshold.  I hate when I 'sort of' remember details I wasn't paying close enough attention to when first encountering them.

In your somewhat unique situation, what is your thinking on effecting backbone links with vlans through some 'bigger' Microwave pt to pt links using Amateur Freqs to overcome marginal link quality on longer hops available w/AREDN supported radios?  So long as there are sufficient traditional fault tolerant links between MESH islands we might do well to free ourselves from a 'One Big MESH' paradigm. Wonder if 'Gateways' to 44net only Internet routes is possible and would effect some measure of additional AREDN utility?  I don't understand the Internet Gateway <-> AREDN relationship well enough yet to know if an additional Gateway 'feature' approval by the cognoscenti will be required for this.  Ditto the AREDN<->OpenWRT relationship.

In our efforts in Mariposa County, using DC from a stand by 'floating' AGM  or Deep Cycle battery (bank?),  a Mobile's vehicle or solar source, or a stand alone mast mounted small solar will be strongly encouraged.   I don't believe our budget sees any large scale solar or Propane or Diesel backup Generators anyplace in the mix.   With this in mind, I do have 1 ea,  prototypes for potted 3 amp and a 10 amp  LifePo4 chargers on the way.  I'm predicting that we'll see a reasonably sharp decline in pricing for LifePo4 batteries over the next year or two.    While you can't use Lead Acid or AGM charging protocols safely on LiFePo4 batteries I am now reasonably confident you can safely and reasonably go the other way and use LifePo4 charging protocols on Lead Acid/AGM batteries.

Will you be planning to use any solar  (or other non AC inverted) DC sourced passive POE injectors?

Too busy to do too much research for a couple of weeks but it is great seeing your progress. 

pax & 73
...dan wl7coo

K6AH's picture
A non-mesh'd backbone

As part of a 3-tiered architecture (backbone, mid-mile, deployed) I intend to implement a TDMA, layer-2, switched backbone in San Diego which I may extend down to mid-mile nodes.  The idea is to provide as much control over the RF congestion as possible... particularly at higher-ground sites, leaving the CSMA for the lowest, ground-level tier.   I have a diagram of this posted in another forum:

You experienced comments are appreciated.

No image

The link you provided doesn't have a diagram there (anymore).  It just looks like gibberish text.  Other posters below your post have images, but not yours dated "Thu, 08/27/2015 - 15:38."  Ah, I see the next poster fixed or somehow put your picture up.  Perhaps you could edit your original post to clarify.

So, basically for 3ghz you're using AirOS on GPS units for timing and just bridging between nodes.  AREDN just sees these links are L2 directly connected, eh?  Not exactly the best for OLSR calculations.  It would be nice if somehow one could "pad" links, so that OLSR could have more info.

Thank you for the info.  Once we get our original "island" meshes installed, we'll surely look at 3ghz-gps units for backbone between our islands.  If I can make it to a SJ node, I'd be interested in linking up for SAREDN access.  Might have to go via a Tracy - Livermore - SJ path, however, as my site is located to cover SJV, not to get over to SJ.

K6AH's picture
Ubiquiti quit making the

Ubiquiti quit making the Rocket M3 GPS, so the backbone is built on standard M3s. We've talked about creating a separate cost metric for L2 RF bridged links, and may still do so after we see what issues surface.  In the current release the link is treated as DTD-connected and assigned an OLSR routing cost of "0.1".

k1ky's picture
Effective Distance - 5Ghz Panel

I have a 120 Degree 19dBi panel at 2200 feet MSL (110' AGL) with a Rocket M5 and can "barely" make a 36 mile path to an AirGrid 28dbi (horizontally polarized - TX 23dbm on a site 880 ft MSL + 132' AGL) and I'm getting about 8 - 12 db s/n at 10 Mhz bandwidth.  Not using it as a primary path, but is usable for control if I lose my primary link.

This is a "clear" path with antennas high on the towers at each end.


K6AH's picture
Not far off

It does seem a little low... perhaps 2-3 dB.  Could be a pointing issue.  I learned a trick from a local ham who owns a WISP company.  Once you establish a marginal link, connect via the link to the remote node and peak your local link antenna using the signal strength as seen from the remote node.  I gained 2-3 dB on a 48-mile link that way.  You probably don't want to do this during weird inversion conditions.

You will also see improvement by using MIMO devices on both ends. Ideally, SNR in the 15-20 dB range should yield reliable 100% LQ results. Of course, you can achieve this through higher power or high-gain antennas.  Generally the higher SNR the higher the data throughput you will achieve across the lnk.

You don't mention if there are commercial 5GHz on the hills, but if so, then you'll need to add RF Arrmor (

Lastly, Ubiquitii devices don't know absolute signal strength, so AREDN SNR and chart functions will baseline the actual noise floor at -95dBm, so a rise in commercial 5GHz interference will be appear as a reduction in signal strength and therefore a lower SNR.

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