Antennas and signal questions

[lawnmowerman]

Current setup:
- Parabolic grid antenna (https://www.amazon.com/Long-range-cellu ... ast_sto_dp)
- Log periodic directional Yagi antenna (https://www.amazon.com/Periodic-Directi ... 075C8FX3S/)
- 25’ LMR240
- MOFI4500_sim7
- 65’ cat6 Ethernet
- ASUS AC1300 router
- Verizon pre-paid unlimited data plan

The antennas are on a 12’ PVC mast and are about 25’ above the ground. The parabolic antenna is on top and the Yagi below it. Both are tilted upward, maybe 15-20 degrees. Until recently, the parabolic antenna was positioned vertically and the Yagi horizontally for cross-polarization (due to the Yagi’s brackets, placing at a 45 degree angle is difficult; and I found as long as they are cross polarized 90 degrees to each other, that worked well enough), with the Yagi a few inches below the bottom of the parabolic antenna’s reflector grid.

The antennas are placed on the west side of my house, with the mast extending from a one story mudroom roof that I have easy access to; after lots of experimenting, I had determined that this was the spot that received the best signal. The antennas are pointed NNE, and I had for a long time assumed the tower was in that direction. But after looking up my signal eNB ID (obtained via the MOFI interface) on cellmapper.net, I found that the tower is actually to the SE. My house is right up against a very steep hill to the south, completely blocking LOS and any direct signal. Below is a terrain map showing my house relative to the tower. Based on this, it seems the signal from the tower on the mountain is coming over the hill behind my house and bouncing off the hillsides to the north of my house, which is where my antennas are pointed. Does this make sense?

signal.PNG

The MOFI is locked onto B4. Whenever I check the signal strength reading via the MOFI interface, there is usually a bit of RSRP and RSRQ variance (RSPR: -109 to -116 dBm; RSRP: -15 to -8 dB), even if there is no wind and the antennas are not swaying at all. My house is surrounded by trees causing signal reflection. I assume reflections, variance, and noise is also increased by picking up the signal bouncing off the hillside, as opposed to coming directly from the tower, yes?

Not long ago, I decided to use the MOFI as a modem only and connect it to an external router. I noticed an immediate uptick in average and max speeds. A week ago, I needed to reroute the Ethernet connecting the MOFI to the router; and in doing so, needed to also move the MOFI to a different location. I took this as an opportunity to take down the antenna mast, inspect the connections, etc. All seemed in good working order but after putting the mast back up and reconnecting the router to the MOFI, I noticed my speed averages seemed down – from 20-25 Mbps to 15-20 Mbps. There’s nothing I did in my reconfiguration that would seemed to have caused this.

When I checked the signal strength reading, the RSRP seemed a little worse than usual, and the signal noisier. But in all honesty, things had been working well enough for a while and I don’t think I had checked the signal strength reading all that often in the last month or so. If anything, I would have thought the signal would be stronger, given the humidity is dropping and leaves falling this time of year. I’ve also never had a problem with tower congestion while on B4 (as far as I can tell), compared to the drastic congestion/deprioritizing I’ve experienced on B13.

During my troubleshooting, I disconnected the parabolic antenna’s cable from the MOFI and switched the Yagi’s cable to the primary port on the MOFI. Surprisingly, I did not get any signal on B4. When I switched to B13, I received a strong signal from the Yagi. I then changed the Yagi position from horizontal polarity to vertical polarity (i.e., rotated it 90 degrees, so that the elements were now pointed vertical instead of horizontal), though not its height or anything else about its position, and was able to pick up B4 (RSRP around -119 to -116 dBm). I am assuming that the antenna is stronger with vertical polarity.

Does that make sense?

Given now that the two antennas have the same polarity, I also then moved the Yagi down the mast so that its elements are about 12-15 inches below the bottom of edge of the parabolic antenna’s reflector grid. Is this spaced out far enough? I want to reduce my signal noise as much as possible. I have checked my signal strength readings and it does not seem to be different – but again, given the usual variance, it's hard to tell. My download speeds seem to be a little higher than before, but not so much that I can tell absolutely for sure. I’m also wondering if I was only getting a signal from the parabolic antenna this entire time, and how much difference the Yagi is or isn’t actually making...

Thoughts?

I’ve also ordered another parabolic antenna and will try having two – in that case, I will angle each 45 degrees to achieve cross-polarity. I am curious to see if there is a big difference or if I should just keep my current setup (the parabolic antenna is not cheap). We’ll see…

As always, thanks all for reading this long post, and all the good advice on the forum!!!

[Dr-BroadBand]

Did having two parabolic antennas help??

[lawnmowerman]

Did having two parabolic antennas help??

Sorry, just seeing this now! Yes, having two parabolic antennas has definitely helped. I also shortened my PVC mast to about 5 ft. (due to the extra weight) and saw no signal loss, and actually more signal consistency since the mast no longer sways in the wind, etc. For whatever reason, I've noticed that once I reached a certain height (basically the height of the porch roof the mast is on), going higher didn't really change anything - and thus allowed having a shorter mast and shorter cable runs.