Band 71 antennas

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DogTho
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Band 71 antennas

Post by DogTho » Fri Sep 04, 2020 10:13 am

New here. Got a MoFi SIM7 locked to TMobile band 71. Got the MoFi and monthly service from wcminternet.com. So far so good but I've been playing with antennas. I'm 11 miles from the tower, supposedly LOS but not visible because of trees. Tried the LPDA the guy loaned me, supposedly made for 600MHz up. I didn't run an SWR curve on it, should have. Tried the Bolton 'super antenna' also. They only get me about -108 signal strength at best. 2 bars what ever they mean. SWR curve on the Bolton is typical of an LPDA, big peaks and troughs from 600MHz up. RSRQ varies from -10 to -17 or so, but I'm getting anywhere from 5 to 20Mbps down. Good enough to stream HD netflix which is secondary to internet usage, but I'm not downloading files.

Long story short, I made a simple Moxon antenna cut for 650MHz on a BNC connector, I have an antenna analyzer and the SWR on it is very good from about 590 way past 700MHz, less than 1.5:1. It is the best working antenna I've used so far. Only using one port on the MoFI, the primary. I did make a wideband 9 el yagi, that also measures a nice swr from 608-690 2:1 SWR BW but with a hump in the high side. I just put it out to try it and I'm getting about -106. I can get generally -102 with 3 bars with the Moxon but it varies from -99 to -106. I've got about 30' of 50ohm cable and a short piece of RG11 for an end jumper.

I'm thinking that at the height I'm trying these antennas, about 20', that's all the signal that is there. Unless I go way up, no antenna I put out there is going to do much past the Moxon. Seems the good SWR curve of the Moxon is what is producing the good results, but I'm not done trying yet. I am still amazed that so far the Moxon has beat the pants off every other antenna I've tried.

Comments?

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Didneywhorl
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Re: Band 71 antennas

Post by Didneywhorl » Thu Sep 10, 2020 9:00 pm

You've gone way overhead on the antenna knowledge :) It would be super cool if you gave us a tutorial in the antenna section on how to run an SWR curve/test on antennas and why you would do so.

Have you tried a high gain flat panel (or even a 2x MIMO) antenna?
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DogTho
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Re: Band 71 antennas

Post by DogTho » Fri Sep 11, 2020 9:24 am

I have a RigExpert AA-600 antenna analyzer. It runs R±jX curves from 0 to 600MHz standalone. I use it mostly for ham radio stuff. I found using the software and computer with it it will work up past 1000MHz. You can look up Moxon antenna. It's simply a 2 element folded element yagi to shorten the width of the antenna. It's dead simple to make with a female N panel mount and a piece of #10 copper house wire. I attach the director to the driven element with 3 pieces of increasing size short shrink tubing. I get the feeling it is working better than the LP or Bolton is because the beamwidth is very wide about 90° for 3dB and the bandwidth is right at 100MHz wide for a 1.5:1 SWR. Non much gain, maybe 6dBi (theoretical)so it will receive fringing at different angles easily. So it's strictly a single band antenna, I'm sure one would probably work on the 700MHz band also.

I've only tried the LPDA and the Bolton antenna, I'm not into spending big bucks on some of these things that sometimes are dead simple to make. Not so much the LPDA if made right. I'm not sure about that Bolton antenna, the price is right up there, but I just didn't see the gain, at least on B71. I'm pretty sure the gain numbers on some of these antennas is way inflated.

But this is not for everyone, my MoFi is locked to B71 TMobile, it's about all that works here in a very rural place.

I finally used 2 of them, set at 45°, tops away from each other, and separated maybe 15'. The signal strength hasn't changed, I typically get -102 RSRP and the RSRQ will vary from -10 to -15, but with the 2 antennas I get downloads speeds of about 16Mbps. When I used just one antenna it would usually run around 5 to 10. So it looks like there is something to the MIMO. This morning I'm only getting -105, but the speed is still at about 17Mb.

I've been working around antennas since the 70's, I worked at an antenna company then run by the guy that actually invented the LPDA back in '52. But I'm no expert, I just have enough knowledge to be dangerous.

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Re: Band 71 antennas

Post by toddw » Mon Sep 14, 2020 2:37 pm

@DogTho: Nice to see you on here. I've been meaning to reach out to you about the Moxon you have.

I do have two RSRF MIMO panel antennas on order, ETA is this Thursday (as you know, you are welcome to try any piece of gear I have in inventory). Not a lot of options for antennas in this space, you tried the one for Bolton and the Yagis I gave you from RSRF. Though once Wilson releases their 5G boosters which use this frequency and others, I would imagine the antenna manufacturers will step up to meet the demand.

I'm going to test the new panels with with a WG1608 router that I loaded Goldenorb on with a Telit LM960. My goal is to determine if our local towers support CA on band 71 to increase our throughput. I also am attempting to determine the majority of the possible combinations we can get with CA on AT&T and T-Mobile. I know the majority the towers will do 2xCA out here, but curious if 3XCA or more is possible.

Also, if you do a band scan on that Mofi SIM7, can you tell me if you can see Band 2 or 12 on it. If so, you may be a candidate for carrier aggregation (CA). I have successfully done 2xCA with Band 2 and 12 on T-mobile and gotten peaks of 40mbps.

@all: I've been lurking here all year, absolutely love the site. It has lead me to testing and development with EC25AF, EC06, and a few low/mid grade Sierra's. It's also lead me to OpenWRT with MM and Goldenorb, I prefer the later.

DogTho
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Re: Band 71 antennas

Post by DogTho » Tue Sep 15, 2020 1:54 pm

I'd like to try some of those other antennas when you get a chance Todd. I doubt a band scan would do much good with my single band antennas, they really only work between 590-700. There's a couple other things I'm thinking about, but as long as I can stream HD, it's not big on the radar. I know there's a band 12 AT&T tower on Fiery Run Road. I think that's where my AT&T phone used to link to. I moved to VZW with the new tower and now I have nothing.

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