26 dBi ultra wide-band parabolic grid antenna

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xdavidx
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Joined: Tue May 28, 2019 4:04 pm

Re: 26 dBi ultra wide-band parabolic grid antenna

Post by xdavidx » Mon Jun 10, 2019 2:17 pm

I heard back from the manufacturer. I asked them if the antennas support MIMO. I got the following response back:

"Thank you for contacting us.

Yes, you can use 2 of these antennas connecting to a single LTE modem as long as you use the correct connector based on your situation."

I tried again:

"Thanks for the reply. Does the mount allow for turning each antenna to be angled 90 degrees from each other for optimizing MIMO?

And just to be clear, you are saying 2 being used together will support spatial multiplexing in order to double the speed?"

Their response:

"Does the mount allow for turning each antenna to be angled 90 degrees from each other for optimizing MIMO?
- The mountig will allow you to adjust the direction of each antenna - you would to purchase an actual mount to go along with the antenna.

you are saying 2 being used together will support spatial multiplexing in order to double the speed?
- Not certain. Utilizing 2 antennas in our conventional application allow us to pull from 2 different towers into our system. Depending on your application the antennas can dial into the 2.5-5 GHz range and, in theory, allow you to achieve a better connection."

I tried again:

"-- Is there some way to find out this information from someone else at Bolton? If I decide to buy 2 antennas, it would be due to them working for MIMO Spatial Multiplexing on a single LTE modem, with each antenna getting signals from a single tower. I'm working in the 700 to 2300 MHz LTE spectrum space. If they support MIMO Spatial Multiplexing, through 90 degree polarization, then the speed should be X when one is plugged in and about 2X when both are plugged in, when both antennas are near each other and angled 90 degrees relative to each other.

There are other people who are interested in the answer as well who I'm in contact with."

I'll post when I get a response again.

In theory, if they are separated by enough space, then it shouldn't matter. The polarized antennas can be close to each other, because they are polarized. Antennas that aren't polarized differently from each other should be able to get uncorrelated signals if they are far enough apart. tgoodwin's test would seem to show that the one grid antenna is benefiting from spatial multiplexing when paired with an omni antenna. The antennas are spaced far apart.

My personal take is that one or two grid antennas are only cost effective if:

- You are a great distance away from a tower, with LOS, and want to pull in multiple bands (we haven't proven they are equally good for multiple LTE bands yet, only Band 4 has been empirically tested). If you want to lock onto a tower far away on a single band, then you can get Yagi antennas priced more reasonably (see: swwifty's setup). And if you aren't too far away, then there are other, more reasonably priced antennas, that will pull in multiple bands and still give you plenty of increased gain (like the 15 dBi panel antennas).

- You want to lock onto one tower out of multiple that are in a relatively close radius and possibly weed out some of the interference from the other towers too. Going with a single grid antenna as the primary would allow locking onto a specific tower and the secondary antenna, as long as it can hear the tower in question, will tag along. The interference improvement would only help the streams on the primary antenna, not the secondary. Going with 2 grid antennas would allow for both the locking benefit and the interference reduction on both primary and secondary connections.

Whether extra hundreds of dollars is cost effective for X Mbps improvement is also a personal decision.

I *might* consider getting one of these in the future and pairing it with one of the 15 dBi panel antennas that I already purchased. And if I get a 5G modem that supports 4x4 MIMO, I might get another 15 dBi panel antenna, for a total of 4 antennas, with the primary being the grid antenna and the other 3 being the panel antennas.

tgoodwin
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by tgoodwin » Mon Jun 10, 2019 3:31 pm

I have the antenna mounted on a Channel Master CM-3090. It allows adjustment on 2 axes. The antenna itself has the standard U-bolt that clamps around a pole. There is no way to rotate it 45 degrees.
CM-3090-4.jpg
CM-3090-4.jpg (47.61 KiB) Viewed 1740 times

xdavidx
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by xdavidx » Mon Jun 10, 2019 3:35 pm

Ah, I took his statements to mean that it didn't even have the U-bolt with it. I suppose you can tilt the channel master left or right? But maybe that only provides 20 degrees or so of tilt in those directions?

tgoodwin
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by tgoodwin » Mon Jun 10, 2019 6:52 pm

Yeah. The tilt is enough to level it from the roof pitch. The bracket is to wide for the fascia to mount it level. So I mounted it parallel then rotated it.

I should have looked earlier. See what you were looking for in the instructions? It's a pro tip.
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xdavidx
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by xdavidx » Mon Jun 10, 2019 11:37 pm

Pro tip!! Good find! :D

For anyone who doesn't see it, it says to use 2 grids for MIMO.

I was thinking of the left to right adjustment grooves on the J-Mount, rather than the ones that allow you to adjust the mast forward and backward.

I'm not able to visualize the parallel/rotated fascia mount.

Thanks for posting that document for the antenna. Am I correct that you can only tilt the antenna up or down by changing which hole one of the u-bolts goes into in their bracket? I guess with an adjustable J-mount, you could move the mast forward and backward to do that too, but it won't necessarily be in line with the tower, so would cause side tilt of the antenna too. Maybe that side to side adjustment on the J-mount could be used to compensate for that. Not an easy adjustment for aiming the antenna up/down. It would be nice if the antenna bracket had a slot instead of just a fixed number of holes.

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JimHelms
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by JimHelms » Tue Jun 11, 2019 5:21 pm

Here is a diagram that we prepared for a customer showing the two separate MIMO configurations for our Grid antennas.


Grid MIMO.jpg
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xdavidx
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by xdavidx » Tue Jun 11, 2019 5:43 pm

Very nice. We still aren't clear on whether the Bolton antennas are polarized correctly and whether they can be that close together and still get uncorrelated signals for spacial multiplexing MIMO. They are too darn expensive to buy and test! :roll: Good to know the LTEFix antennas are polarized properly.

I wasn't even aware LTEFix had grid antennas. That looks like a nice solution for anyone needing that frequency range. And this is the proper way to supply an LTE mount (quoted from the LTEFix website): "The antenna is supplied with a 60 degree tilt and swivel mast mount kit which allows installation at various degrees of incline for easy alignment. It can be adjusted up or down from 0 to 60deg."

The link to that antenna: https://ltefix.com/shop/antennas/wifi-a ... -n-female/

xdavidx
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by xdavidx » Wed Jun 12, 2019 1:06 pm

Final reply from Bolton, in response to these previous replies:
"-- Is there some way to find out this information from someone else at Bolton? If I decide to buy 2 antennas, it would be due to them working for MIMO Spatial Multiplexing on a single LTE modem, with each antenna getting signals from a single tower. I'm working in the 700 to 2300 MHz LTE spectrum space. If they support MIMO Spatial Multiplexing, through 90 degree polarization, then the speed should be X when one is plugged in and about 2X when both are plugged in, when both antennas are near each other and angled 90 degrees relative to each other.

There are other people who are interested in the answer as well who I'm in contact with."
"We checked with the RF engineer from the manufacturer and he said yes if set up correctly."

coldknob
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Re: 26 dBi ultra wide-band parabolic grid antenna

Post by coldknob » Mon Jul 08, 2019 10:00 am

Sorry to be so late to this party but I believe I have found the ultimate "need for speed" solution.
Time won't allow me to go into all of the details of my journey, but needless to say I have amassed quite a collection of antennas, amplifiers, cables etc.

My home is in the mountains, closest towers 6 mi. away. Predominately band 12, 5mhz. but 2 towers with band 2, 15mhz which provide much better speeds. Trouble is I couldn't pick up the band 2 signal at all.

Fast forward several months and I settled on a parabolic grid wifi antenna which gave me consistent speeds of 25 down on band 2 and effectively blocked the band 12 signal. A few months of tinkering with the cables, antenna placement, etc. got my top speed up to 45 down, 15 up which is more than I need.

However, I always wondered what I could get if I had a mimo setup but 2 grid antennas at 45 degree angles is a larger footprint than I wanted and I was satisfied...until I came across the existence of a mimo feed horn that replaces the one on your present antenna. Found a Chinese supplier on eBay and 1 month and $55 later got it and bolted it on.
MVIMG_20190708_101435541.jpg
MVIMG_20190708_101435541.jpg (50.32 KiB) Viewed 1171 times
The results were pretty amazing. 70 down 25 up consistently, 85+ down frequently. This is from a tower more than 7 miles away. $40 for 2.4mhz parabolic grid antenna, $55 for 1710-2710mhz feed horn = 24X2 gain for less than $100.
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swwifty
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Location: NE GA Mountains

Re: 26 dBi ultra wide-band parabolic grid antenna

Post by swwifty » Mon Jul 08, 2019 7:44 pm

nice setup! Based on the bands you're using it sounds like you're using AT&T?

Mind sharing links to the antenna and feed horn you got?

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