Antenna for rural broadband

[deanfourie]

Hi there, im on a One NZ mobile 4g broadband, which is not too bad but can be huge with latencies at times.

My SINR generally sits between 3 and 7db but fluctuates hugely. I will often get huge lag spikes from time to time. I am trying to reduce that.

I am looking at getting one of these LPDA MiMo antennas, just wanted a second opinion before spending the 300 on it.

https://www.trademe.co.nz/a/marketplace/...52dd79-009

Appreciate the feedback/

Thanks

   

[Seán]

If those readings are from router's internal antennas, your signal strength is actually pretty good, but just suffering from interference such as from a mast operating in another direction. In this case I suggest getting a MIMO panel antenna, which are generally much cheaper and easier to install as they just need a basic TV antenna mounting bracket instead of a long pole for 2 LPDAs. Just make sure the panel antenna covers the 1800MHz band as some are band specific, e.g. 700-900MHz for 4G bands 8, 20 and 28.

Generally I would recommend LPDAs when the signal is very weak (e.g. worse than -100dBm RSRP) or where the interfering site / mast is within 45 degrees of the one you are connecting on.

[deanfourie]

Thanks for the reply.

Can you confirm one of these is what im looking for.

https://www.trademe.co.nz/a/listing/4554...f=LQkXek2G

https://www.trademe.co.nz/a/listing/4557...f=LQkXek2G

https://www.trademe.co.nz/a/listing/4554...f=LQkXek2G

Thanks again!

[Seán]

At a first glance the first antenna looked ideal as it covers the high frequency 4G bands such as 1, 3 and 7 and I think it is one I suggested before.  However, after having a closer look, I noticed it is using F connectors and what appears to be RG-6M 75Ω cable, which are for receive only communication such as Terrestrial and Satellite TV.  This probably explains the very low price as satellite coax is very cheap compared to proper 50Ω cable.  A pair of 5m+ leads can cost more than the antenna itself, particularly for quality LMR-195, LMR-240, etc. cable.

The problem with using 75Ω cable and connections with transmitting signals (e.g. uploading) is that the impedance mismatch between the modem's 50Ω connection / circuit will lead to some of the transmitted signal being reflected back.  This may cause problems with 2 way communication (e.g. voice / video calls) where the modem radio gets swamped with noise from the reflected transmitted signals as it tries receiving signals at the same time. 

The second antenna is 4x4 MIMO intended for routers with 4 antenna connections such as some 5G routers.  You would need to modify your router to properly use that antenna and would only be worth it if you know your 4G site is 4x4 MIMO capable and has good backhaul to deliver the additional throughput, otherwise it may be perform no better than an equivalent spec 2x2 MIMO antenna.

The third antenna gain seems quite low, likely due to it being a compact antenna (15.5 x 15.5cm), however, I reckon it is sufficient to improve your SINR reading and performance, especially as it will be picking up the signal outdoors.

From a quick look at other listings on that Trade Me store, the following is a higher gain model of that third antenna which I suggest going for.  You will need to get a pair of TS9 to SMA adapters to attach the SMA ends to your Huawei B818 router as this larger antenna doesn't mention about including them:

https://www.trademe.co.nz/a/marketplace/...4564654009

[deanfourie]

Thank you Seán for your very informative answer.

And thanks for your tips on what to purchase, I have gone ahead and will try the one you suggested.

One more question, what do I need to look out for when extending the coax? Obviously, this will introduce some loss but I want to try and obviously eliminate as much loss as possible.

Thanks again.

[Seán]

There are a few things to check on extension coaxial leads:

First check that the ends are SMA and not the similar RP-SMA (Reverse Polarity SMA), which Wi-Fi uses. If the listing shows close-ups of the connectors, there should be a centre pin in the SMA female connector.

For the cable itself, try going for LMR-195, H-155 or LMR-240 cable. These have a loss of around 0.53dB, 0.4dB and 0.36dB per metre on band 3, respectively. As your RSRP signal strength is quite good, even the cheaper RG-58 with a loss of around 0.8dB per metre will also work well. The main one I would avoid would be RG174 (which looks thin like headphone wires) as it is very lossy cable at around 2dB per metre on band 3, i.e. a 5m extension would drop the RSRP by about 10dB.

The only listing I came across on that Trade Me store is the following and you would need a pair cables. It would be worth checking other stores to see if they carry SMA extension leads:
https://www.trademe.co.nz/a/marketplace/...4566625231

I would not be too concerned about getting the highest grade coax other than making sure it is 50 Ohm cable. Basically, antenna gain and cable loss are not directly comparable. The higher the antenna gain, the better it performs at rejecting interference from outside its beamwidth, improving the important SINR reading. Cable loss on the other hand just weakens the signal, it generally does not affect the SINR or download performance as long as the signal strength is kept within -100dBm RSRP and the upload performance within around -90dBm RSRP.

[deanfourie]

Thanks again Seán.

Hopefully I can pick your brains on this one. I used to have a connection with a different provider, was getting much better speeds then what I am now with my current provider, however the usage plans were different being one was limited and one was unlimited.

Both appears to be using the same tower, and the same band.

I have measured my distance from the tower, I am 3.1kms from the current tower I am connected to. I also noticed there was another tower literally across the road from me 500m away. (using maps to measure). I did some investigation on these tower and it appears that both towers offer the same bands.

Tower @ 3.1km
   

Tower @ 500m
   

When I look at the close towers Polarization, I can see that it appears to broadcast at a very specific direction as per the image below.
   

Now, I know I can force bands one the Huawei routers using huactl, my questions is can I, or is there any point trying to connect to this closer tower, or will I even be able too?

It is strange how I used to, on a different provider, get speeds of up to 100mpbs, averaging 30mbps, now I seem to be averaging just 10mbps, different provider, same band, same tower.

My other thought was to try force band B28 (700mhz) at this range from the 3.1km tower?

Appreciate your thoughts,

Thanks again!

[Seán]

With the directional antenna, you can try aiming for the nearby mast. The main issue I see with being directly in-between the two sectors (191 and 191) is that the SINR will likely be very poor and probably perform no better than the further out mast where you are within its sector's beam angle.

Congestion and backhaul capacity is another factor that affects the speed, particularly with limited / capped plans. A provider that charges more or has capped plans will usually have higher speed as users are more likely to choose the network with unlimited data or at least be more careful with their data usage with a capped plan. Likewise, each operator will have different backhaul links, some which could go across several congested microwave hops before reaching a core fibre backhaul link.

[deanfourie]

Hi Seán,

I purchased and today installed the WMM8G-7-38-5SP antenna on the roof,

However, I did notice any change in the SINR or speed/signal strength at all.
Are these antennas directional or Omni? I did change the router settings to use the External antenna and not the internal.

Little confused.

Thanks

[Seán]

There should be a change in the signal readings when you attach the antennas leads. Try placing your router flat on the ground temporarily to see if it affects the signal readings . If the signal readings drop, then the router is still using its internal antennas.

The outdoor antenna will need to be aimed towards the mast, possibly 10 to 20 degrees either side depending if it is picking up interference from another mast. You should see the RSRP and SINR readings raise / fall as you turn the antenna.

[deanfourie]

There should be a change in the signal readings when you attach the antennas leads.  Try placing your router flat on the ground temporarily to see if it affects the signal readings .  If the signal readings drop, then the router is still using its internal antennas.

The outdoor antenna will need to be aimed towards the mast, possibly 10 to 20 degrees either side depending if it is picking up interference from another mast.  You should see the RSRP and SINR readings raise / fall as you turn the antenna.

Yea that's weird, there is definitely no increase in SINR, and as far as I know, the external antennas are working....

One thing I did notice is I now appear to be connected to a different tower, not much further away. Still floats between 9 and 14db.

[deanfourie]

Another weird thing is, I cannot find this radio.

I can find 454657 and 454659 but cannot find 454658 anywhere?

   

   

[deanfourie]

Ok here is a weird update.

I started playing around with the antennas on the back of the router, I was getting around 30 down and 0.8 - 1 up. So I switched the antennas around and did another test, this time I was getting the best speeds for a long time 30 up and 50 down.

Now, the weird thing is that if I unplug the antenna from the port labelled DIV, I get the exact same results. Almost like the MiMo is not working.

So, i've just left one antenna wire plugged into the MAIN antenna port.

Any idea why this could be?

[Seán]

The huge difference in upload speed by swapping the antennas leads indicates a problem with either the antenna, coaxial lead/connector or the TS9 to SMA pigtail that you moved to the DIV port.

Try swapping the two TS9 to SMA pigtails around with the current antenna lead that you have connected. If the speed drops, then this TS9 to SMA pigtail is faulty. Otherwise the problem is with the other antenna or its coaxial lead/connector. In this case, check the pin in the SMA connector is not bent or loose.

With the missing cell ID on CellMapper it is probably has not been mapped yet, particularly if you seen the missing cell ID appear on your phone or router. CellMapper mainly gets its cell information from users running the CellMapper App in the background while travelling. Whenever it discovers new cell IDs, it adds these to the map based on the phone's GPS coordinates, eNB ID, signal readings, etc. Another possibility is that the mast only operates band 3 on the affected sector.