Basic 5G 4x4 MIMO outdoor antenna selection/spacing/orientation Qs  - Page 1
Forum section: electronics / rf-microwave

author: pipe2null
author_rank: Regular Contributor
timestamp: June 17, 2023, 07:16:59 pm
content: I'm debating between a 4x4 MIMO Panel and 4x4 LPDA's (both advertised at 11dBi gain for 600-6000MHz) for external outdoor antennas for my 5G cellular router (sub-6GHz bands), and what optimal alignment and spacing would apply to the LPDA array if it makes sense to go that direction.Please forgive my newbness on the subject, I've looked around the web but only found rather vague answers. "Generally", if there's trees, supposedly you should go with a Panel, and otherwise go with LPDA when targetting only a single tower (single specific direction), but what counts as "trees" is exceptionally vague regarding density. As far as 4x4 LPDAs go, the only info I've seen is that for modern 5G tower use they're supposed to be cross/X-oriented at 90 deg from each other/45 deg from HO or VO. But I have found nothing on the optimal spacing of the antenna pairs for optimal isolation/coupling/diversity/etc. For the LPDAs, I saw a comment on a site that implied that separating the antenna pairs by a couple meters improves overall performance, I am guessing due to better MIMO diversity/etc, but no real idea on the subject and I may have misread.I am 4.31 km to the tower, and topographically there is nothing between me and the tower other than a few regions of trees but no dirt hills/rocky bits blocking line of sight. Somewhat dense smallish patches trees, the RSRP has gotten worse by something like -5 to -10dBm compared to a few months ago, wintertime lack of tree leaves to current summer time, which is irritating since everything else is just flat farmland. But those numbers fluctuate too much to gauge accurately, so I'll just say "anecdotally", speed has decreased a bit since the trees grew more leaves. My current router allows direct AT commands to the modem, so I've been able to scan for cell tower info (for all ISPs within range plus cell towers used by electric utility for IoT meter reading, love that feature) and know the precise location of my tower thanks tohttps://ispdesign.ui.com/andhttps://www.cellmapper.net/, drove by to verify.So:Should I "automatically" opt for the Panel or should I play with the LPDAs?If LPDA's have a reasonable chance at performing better than Panel with the presence of a vague unknown density of trees, what should I expect the optimal spacing/positioning/orientations to be for the individual LPDAs relative to each other and the tower in the 4x4 MIMO configuration?Thanks

author: pipe2null
author_rank: Regular Contributor
timestamp: July 09, 2023, 07:16:06 pm
content: Revised Q's:1) Spacing and orientation guidelines for using Parabolic Antennas in a 4x4 MIMO configuration?I'm currently trying out 2x "2x2 MIMO" parabolic antennas for an overall 4x4 config. They are cheaply built and from a "psuedo-brand" off amazon, but they are also the only parabolic antennas I have heard of that have both a horizontally and vertically oriented antenna on the same horn (that you assemble at 45 deg) of the same dish for an overall 2x2 per dish. Thought I'd give them a try, only need 2 dishes for a full 4x4 MIMO. The advertised "30dBi per antenna" is BS of course, but previous SINR was an average of ~5-7dB using 9dBi paddle-omnis, now with parabolic is typically better than 20dB even with signal loss from the included 15meter cables.2) Is there such a thing as adding a LNA (or something similar) between my 5G cellular modem/router and the TRANSmitting antennas, or other way to boost upload?- My current average download rate is appx at least ~10x but usually ~40x my upload speed, so I suspect I may have issues with transmission power from the M.2 cellular modem. I'd just try it, but the FCC frowns upon such tinkering without a license, and I have little idea what Im doing in this subject area.I'd appreciate any comments, thoughts, advice on the subject. Getting ok-ish internet service at my location has been a massive PITA and I do not live way out in the country. I need to get/verify my setup to be at least as optimal as reasonably feasible to finally call this epically long project as DONE.Thanks