MIMO antenna vs two separate antenna's?

[Smitty77]

I posted a similar question on the Escapees too, but trying to increase exposure to get more help!

We just got the ATT Unite Explore Hotspot, which is MIMO, and has two ports to provide MIMO external antenna support.

As I looked at the offerings of a few companies that provide either dedicated Cellular MIMO or combo Cellular/GPS/WiFi antennas - I was surprised to see from 2.5-4db values.

I've read a few RV and boating forums where individuals are going with two separate antennas, and then hoping them into the two separate ports. But they don't go into any details as far as physical setup type info.

1) Do the two separate antennas need to be XX amount of separation? And what is a good range for XX value?

2) Will to full spectrum 3/4G LTE ranged antennas with higher db gain values, work better then a purpose built (Usually with built in ground plane.) MIMO antenna?

3) (On edit - I left this question out at first!) I see some comments about opposite polarization when looking at MIMO units, but it does not seem to be consistent(?).

(Due to the lost of db for each connection to get a signal down and converted to the Unite Explore's ports, I thought having higher db gain to start would yield better performance(?).)

I was considering:
-Wilson 4" stubby antenna (Will need ground plane's.)
-Maximum Signals 13" magnetic mount (Ground plane's too.) (Have one of these with our Max Signal amp, and it performs surprisingly well.)
-BoatAnt (Non MIMO, as the MIMO unit has had some teething problems.)
-Wilson Trucker antenna
-Other's to consider? (Please.)

And other then my question about separation, which I'm assuming does not need to be too far(?), as the all in one MIMO antennas are usually in a pretty small package. I'm also assuming that it would be 'plug & play' into the Unite Explore's ports? No setup configuration options for antenna's that I can see while looking at their device.

Why two external antennas in MIMO vs just using the Max Signal amp? We've found that with all of the amp's we've ever had, and of course many have reported this too, that sometimes when in a good to moderate signal area, the add noise of an amp can actually slow data speeds. (Stronger amplified signals with potential added 'noise', do not always yield faster data speeds.). So many reports of MIMO antenna only devices having faster download speeds then when amplified. Adding external antennas, should improve this possibility of increased download speeds.

But I admit I'm posting this here because too many times in life I need to quote the old Dennis Miller HBO show line 'I could be wrong!' (Wife would nod her head to that comment..)

TIA for any suggestions. (And note, I'm not opposed to a all in one MIMO antenna, it was just the lower db values that had me concerned.) Best,
Smitty

[RKins]

What makes MIMO work is one antenna is horizontal polarized and the other vertical and they both are usually in the same housing. Not sure of you can "make your own" using two separate antennas.

[Smitty77]

Originally Posted by RKins

What makes MIMO work is one antenna is horizontal polarized and the other vertical and they both are usually in the same housing. Not sure of you can "make your own" using two separate antennas.

Thanks for the response. And either am I! But I'll see if I can re-find what forum I was on where someone was trying with two stubbies... (Either boating cruisersforum or Technomadi's RVmobileinternet. (Don't think it was the sailing community forum.)) And, it's possible I miss read what they were going to experiment with.)

Most of the cellular band width MIMO's have such low db gain... (At least that I could find.) that is why I was hoping to use two individual higher gain units. But, if the tech don't work that way, I sure won't be able to do it!

Thanks again, and best,
Smitty