Why do I need MIMO for Internet on the Boat?

MIMO means multiple input, multiple output, or basically two antennas. Now there are a lot of nice solutions out there, single packet solutions, but we actually found a lot of success and positive feedback from customers using the Alfa AOA-M4G Marine Omni, or basically just that one but in a single packet times two.
So you take the same antenna, put two of them somewhere on a boat, and that creates a MIMO system. And you can actually control and manipulate the level of MIMO or diversity that you want for your system. Now why would I say that? MIMO means you get two signals into your receiver. Me, as an antenna engineer, I don't always know or don't always have to know what exactly the system designer, the radio, those designers, are doing with the two signals. I need to know how can I get a clean signal and a different signal to the radio, that's my biggest focus.
That's what I must do because sometimes it's minor diversity, sometimes it's MIMO and there's all sorts of techniques that can be used. But if they don't have a good signal, they mean in the software radios, software guys, software engineers, then they can't do much with it. So what we basically want to do is get two signals into the radio that are unique but still from the same source and clean and well behaved. That antenna, the AOA-M4G, the Alfa Marine Army basically, is just a simple classic good antenna. It works from 650 megahertz, so well below the 4G band for Australia and it actually works really well up to 4.5 gigahertz. So, it really covers everything beautifully through the whole 5G band in Australia as well which is what we want to do.
Now, what you can do with this antenna, you have one antenna in one end, you have one antenna on another end, and I'm here, I travel to San Francisco. I'm not going to take 10 antennas with me as props just for video. Hopefully you can appreciate that. If you put them side by side but you space them out, you get spatial diversity. That is a good thing because basically the path length between you and the source is different. And if there's a reflection from the water, it will behave different from one source that's closer than the one that's further away. However, if say you are the source, you being the camera, there is a point where when I turn everything is going to be exactly the same, so exactly the same distance. So that's not always going to work ideal.
You can control that, you can now go higher. So you have two antenna rather than just going like this you can also go up and down down a little bit. So now you have two levels of spatial diversity that you can play with. Don't take an Omni antenna and I'll make a separate video on that in a few days time as well. Don't turn the Omni by 45 degrees 'cause you're going to muck up the whole working off the Omni by itself. So that's, let's not do that. Let's just take your Omni antenna, two separate Omni antennas, space them, one higher than the other one. You have quite a good diversity system going. Two of those antennas on our website. If you have any questions, let us know. There is significant positive customer feedback on that antenna in a marine application and also in stationary in land situations as well because it just works well. But in land situations often you can't go for stationary so you go for a fixed direction antenna.
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[@michaelsimpson9779]

I'm guessing, because I'm in holiday mode and it's not my speciality, that the wildly different radiation patterns of the omni as compared to the directional antennas is why the cross polarisation is a bad idea. At an angle with the omnis, you'd have a massive null zone at times in mobile applications.

[@RFShop]

Hi Michael. The reason why MIMO / 45dgr is messy for an omni is quite difficult to explain via a typed response. I recorded a response and will upload my first TH-cam QA session this coming weekend. Please look at that response and see if it makes sense :)