Hi there,

As detailed here, I set up a BLACKHAWK LPDA ANTENNA 698-4000MHZ 12/14DBI antenna. I was originally going to get two and put them into MIMO configuration, but as I was hitting the max throughput allowed by Vodafone at the time, I didn't bother. 

Two things have happened since then. Vodafone have changed their data restrictions, which has allowed ISPs to sell far more generous plans for a much better price. And it seems in the process, the speed limits were removed. Rather than being capped at 30 mbit/s, I was on occasion hitting around 42. 

The other thing that's changed is in the past few weeks, the speed has plummeted. Often it's around 8 mbit/s, and seems to peak around 20 at best. Also, I get dropouts every every 5 to 10 mins (at a guess). I was having either of these issues previously.

It might be an influx of people to the Coromandel for summer, although that's usually in late Dec.

Anyway ... I am going to get a second antenna and set them up in MIMO.

HERE'S MY QUESTIONS

1. Until recently I understood in a MIMO config the antennas are relatively close to each other. The one-piece brackets sold for such have perhaps 10 to 20 cm max between the antennas.

But then I came across this article, https://www.evdodepotusa.com/get-the-highest-speed-possible-from-your-yagi-directional-antenna/ , which says to have them at least three feet apart. I asked the authors about that (since the photos on that article shows them less than 1 foot apart), and their response was that those are pictures from the manufacturers, and they don't represent the best set up. They sent me this photo as an example of what works better: https://v2uploads.zopim.io/5/D/c/5DcyCYIG19wrZ0vLefAsE08c84AykYRM/2ff269d7cd0d7cf595e2c33043f4cb4b791e3639.jpeg

I reached out to telcoantennas.com.au in Australia (since they do installs and sell the related equipment) and asked what they thought about that. Their response was ...

"If you have two separate Antenna elements it is best to keep them at least 300mm apart to limit the potential interference between the two, at 900mm separation the interaction is negligible.
This is purely to avoid the Antennas patterns skewing each other, the effect is similar to putting two magnets of the same orientation together."

Can anyone shed some light on what the story is here? Do I need to set them up with a 600mm or more apart, in order to get better signal?

2. Also, a related question. in some MIMO config images I see the antennas at single 90 degree angel to each other (creating somewhat of a cross config).... like this: 

... and in others they are at a 45 + 45 (which is also 90 deg, but achieved through a 45 on each, creating more of a wedge configuration), like this:

Does it make any difference how the 90 deg. offset is achieved? 

Thanks very much ...

Jonathan

@coffeebarron, I figure you'll know the answer to this, if you have the time to chime in. I'll also PM you for a price on a BLACKHAWK LPDA ANTENNA 698-4000MHZ 12/14DBI.