Advice for 54km using c5c

Hello. I need some advice,

This is my first time to use this kind of tech, i did some research also about ptp.

Here’s my situation.
The distance is 54km from A to B. Design Tool recommends the c5c, i’d like to send 300mbps to point B. What is the best dish antenna for me?

Please move my topic if im on the wrong section.

Welcome, hope your able to get the information you are looking for.

So first off, it looks like you have found some sort of bug in the Mimosa Design tool, it seems to be saying you have a link that does not have LOS (Line of Sight). You will definitely need towers that are tall enough to see each other.

The raw distance isn’t much of a problem, but 5 GHz (the frequency that most Mimosa gear works on) really does need LOS. You will want as big of an antenna as you can afford though, +36 dB would be where I would start. Parabolic antenna JRC-38DD DuplEX Precision : Antennas for 5/6 GHz parabolic : Wi-fi antennas would be where I would start looking. (Note, these things get expensive quickly) That said, Jirous is going to be on the higher end price wise and there probably are others that would be cheaper. I have a link lower to a Mimosa Blog post about shooting over water where they have pretty reasonably priced antenna.

Lastly, I wouldn’t recommend this link without some conversations with a real RF planner. You are going to be shooting over water and there are some really significant issues that happen when shooting over water. (Called Thermal Inversion, basically your signal hit’s a mirage and gets deflected just like light and that plays hell with your link). If you are bound and determined though, Mimosa does have some documentation on how they “can” get around the issue somewhat (it does require that you use an A5c radio on one side of your link and that you use another antenna. Deploying a Diversity Link | Mimosa by Airspan

Thank you, very important info.

I have both GREEN line for B5c and c5c, and looking for B5c is much better than c5c? Also I adjusted my pole height to 20meters. LOS says YES, and the line is GREEN I supposed i don’t have problem with B5c?

Sadly Parabolic antenna JRC-38DD DuplEX Precision are not available in the Philippines. And I cannot find any 36+dbi dish antenna here.
Anyway, can I partner this to B5c? It has 30dbi.

and this one has 34dbi※In-Stock!※-Ubiquiti-AirFiber-5GHz-34dBi-Slant-45-Antenna-(AF-5G34-S45-I-AF-5G34-S45)-I-PTP-Antenna-i.561674214.12741846255?sp_atk=d229fbc0-2939-4071-93d2-17cda1555adb

You said you don’t recommend c5c, what link do you recommend?

Yes, the design tool seems to be broken, at 58 km you are looking at a fresnel zone size of 3000 m, which at 20 m pole height just isn’t going to work. It seems that Mimosa’s design tool doesn’t account for water at all which you need to avoid interacting with for a reasonable and steady signal. The tool is saying you have LOS, but Line of Sight also requires area around where your signal is traveling to be unobstructed as well. FYI, the Mimosa design tool, while a very useful and good tool, is not a replacement for a real RF Engineer for long links like this. Also you can look at the picture and see that there is water in the path of your link.

This is what you should be looking for:

Playing around with the tool you will not have a clear Fresnel zone until you have a tower that is +75 meters tall, on both sides. Even at that height you will have issues with thermal ducting/inversion which will plague your link with signal fluctuations.

There are several different options for dealing with that issue, one is to build a diversity link which will utilize multiple antennas to keep signal strength good when the signal gets bent and reflected. (I linked to Mimosa’s Blog post about it in my last post) Another is to use an antenna with a very wide beamwidth, but that only works over short distances. You can also attempt to go over the reflections, my understanding is that with really large structures you can avoid thermal inversion/ducting altogether, but you have to be really high up. Finally, the solution taken by major telco’s in the USA was to go around large bodies of water. (Basically they would have relays of towers and short links to get around the issue.

None of these options are cheap and the first two require that you have a real RF Engineer work with you on the link.

I have never asked Mimosa support for RF Engineering help, but you might contact them and see if they have anyone who could help. But I have never heard of that, so I don’t know.

To put it simply, you need a much taller structure to mount to on each side at a dead minimum. But you will have all sorts of issues unless you deal with the thermal ducting/inversion issues I have been talking about. To be straight with you, I would not build this link period, you will have lots of problems and erratic behavior.

Per your antenna questions. If you were to use the C5c then yes both antennas will work with those radios, the B5c will need adaptor cables because it has N Type connectors and both of those antennas use SMA type connectors (which the C5c has).