Hi Carlos
Its more than likely that your mobile has a superior CAT rating than your router, and it is also aggregating when its close to the mast, possibly with one of the higher frequency bands that you can't receive 2km away at your home, hence why u see greater speeds closer to the cell? You would need to do some more research on this to determine what your mobile is doing exactly. Your mobile also has no coax loss so its radio is able to receive more of the received power. If practicable, take your router and antenna for a drive and see how that performs closer to the cell?
IMO comparing your signal stats, they are almost identical to my stats, and I have seen 71 Mbps/30 Mbps, on my B535-232 on Three, CA (4G+) with B3 and B20, at 4am when nobody is online, so I would be inclined to say that the radio connection you currently have, is capable of faster speeds without being improved upon with an external antenna. (assuming you currently get CA on B3 and B20 at home? (your router maybe only reporting the primary band 3, but you could well be CA with B20 already and not realize it!).
To answer your question though, my first impression is that trying to improve your radio connection stats by adding the directional 3G 1.8Ghz yagis you have asked about, would be unlikely to improve your thru-put. It would also limit you to band 3 only, as these yagis dont cover band 20. Your fall back option would be limited to 3G, (but only if there was a 3G cell in the direction of the antennas!) These yagis are also quite long boomed, so the radiation pattern will be quite narrow, and will also have narrow side lobes, so aligning them could be a pain. IMO a more suitable application for these yagi's would be if you were quite distant from the cell, and could currently only get B20, but wanted to try and get B3 for better thru-put.
One of the other guys could probably help here, as I'm not that clued up on cell types, but as far as I understand, the type and model of cell you are connected too will also determine if you can achieve 2x2 MIMO on B3 or not?
IMO Given that you are only a few KM away from the cell, there maybe a fair chance that you could achieve CA by using a directional multi-band panel antenna like the Pyonting XPOL-A0002, which I have also found to be very good also compared to many of the other off the shelf solutions that plague the market, but they are expensive. These have a rather wide horizontal radiation pattern of around 30 degrees so they are not difficult to align, and would give you a fall back onto B20 if that was supported by your connected cell. They also have enough gain over the bands to overcome any coax losses, and other system influences (see below).
I would however not guarantee that adding any external antenna, would definitely improve anyone's signal or thru-put though, as there are simply far too many factors that are unique to every situation to consider, to do so with any confidence, so as suggested if you do take the plunge having a returns policy is a definite benefit.
Whilst I am here, I think it is worth pointing out one very challenging aspect of trying to add an antenna onto a device on this mobile broadband system, is that the entire system is designed to control the emissions on every connected device, by adjusting the device's transmitted power based on the signal metrics it receives when negotiating and maintaining a connection.
It has to do this to adhere to strict public health emission standards due to the proximity of mobile phones to peoples bodies, but also to manage the amount of noise and interference it has on other services and spectrum users, and ensure that a connection is maintained as a device moves away from the connected cell, like in a moving vehicle etc. When out of range of the cell, or in the case of a cell losing service, the connected device is handed over to an alternative cell where available. The entire process is seamless and this applies to static installations like routers as equally as it does mobile phones.
It is worth bearing in mind that a voice call requires far less bandwidth than a data call, and these tend to work as well at greater distances from the cell as being near to it (note:- that if the radio power was fixed on your mobile, your device would be emitting a signal far in excess of what was required for the connection when u were close to a cell, and you would be exposed to more RF radiation !).
As data calls require much more bandwidth than voice calls, when a data call is initiated, the device radio power is stepped up to provide a stable connection for the data call to be initiated and maintained (e.g. Watch your mobile signal bars when you turn on data mode, and open a web browser! Depending on how good your signal is to begin with, it will often jump up a bar or two. The system has just increased the power on your device to accommodate your data call!) Another point worth considering is that the more bandwidth required for the connection the more noise the device will have to contend with.
The system is infinitely more complicated than I have described above, but this dynamic nature presents its own set of issues when trying to add an external antenna to a device, as the system can reduce the radio power as the signal metrics are improved upon when adding an external antenna. The biggest benefit of an external antenna by far, is that you can position it outside, where less of the received signal is being absorbed and reflected by structures, curtains, windows, walls etc etc.
IMO This power management aspect (system influence) is mostly overlooked when considering an antenna by the majority of people, however it largely provides an explanation as to why so many people add antennas and do not see the huge improvements they had hoped for....Another reason is that many cheaper antennas with fixed coax cables, that are flexible and long enough to be useful for the end user, carry quite poor attenuation losses for the frequencies used in mobile applications.
In general, the thicker the coax the less the losses will be. For example, look at how thick the cables are that run into cell sector antennas are, some are near 2" diameter. (The radios are usually located at the base of the cell tower btw).
By comparing the EIRP (Effective Isotropic Radiated Power) on a few randomly selected antennas, we can see how much the effect that power levels and coax losses have on the effective radiated power levels....
Ref :-
EIRP Calculator
I am not sure of the actual limits or standards that the GSM/3G and 4G systems have to comply with, so l have made some assumptions for the purpose of this illustration. I have assumed that a mobile/router device can operate at between 3 mW (6.7 dBm) and 1 W (30 dBm) power output. For simplicity, I have also assumed that we are only talking only about band 3 (1800Mhz), as the losses and antenna gains will vary on each part of the spectrum.
Case 1 - Router with internal antenna. (Set to the lowest power output by cell)
Router Power - 6.7dBm
Coax Loss - 0
Antenna Gain - 2dBi
EIRP - 8.7 dBm
Case 2 - Router with Pyonting XPOL-A0001 external antenna (Set to the lowest power output by cell)
Router Power - 6.7 dBm
Coax Loss - 5m HDF195 (0.58dB/m @ 1.8Ghz) - 2.82dB
Antenna Gain - 4dBi
EIRP - 7.88 dBm
Case 3 - Router with Pyonting XPOL-A0002 external Antenna (Set to the lowest power output by cell)
Router Power - 6.7 dBm
Coax Loss - 5m HDF195 (0.58dB/m @ 1.8Ghz) - 2.82dB
Antenna Gain - 9dBi
EIRP - 12.88dBm
Case 4 - Router with 7.5dbi Omni Directional external Antenna (Set to the lowest power output by cell)
Router Power - 6.7 dBm
Coax Loss - 5m HDF400 (0.2dB/m @ 1.8Ghz) - 1dB
EIRP - 13.2dBm
Case 5 - Router with internal antenna. (set at max power output by cell)
Router Power - 30 dbm
Coax Loss - 0
Antenna Gain - 2dBi
EIRP - 32dBm
Case 6 - Router with Pyonting XPOL-A0001 external antenna (set at max power output by cell)
Router Power - 30dBm
Coax Loss - 5m HDF195 (0.58dB/m @ 1.8Ghz) - 2.82dB
Antenna Gain - 4dBi
EIRP - 31.18dBm
Case 7 - Router with Pyonting XPOL-A0002 external Antenna (set at max power output by cell)
Router Power - 30dBm
Coax Loss - 5m HDF195 (0.58dB/m @ 1.8Ghz) - 2.82dB
Antenna Gain - 9dBi
EIRP - 36.18dBm
Case 8 - Router with 7.5dbi Omni Directional external Antenna (set at max power output by cell)
Router Power - 30dBm
Coax Loss - 5m HDF400 (0.2dB/m @ 1.8Ghz) - 1dB
Antenna Gain - 7.5dBi
EIRP - 36.5dBm
As we can see from these examples, the power level has a massive effect on the amount of RF that is radiated from an antenna, which in turn will directly influence the ability of the device to establish a connection.
As we the end users have no control over this power level on our devices, you can see why adding an external antenna can be so challenging !
This article for the British Medical Journal, I found to be very good to explain the basic operation of the system, but also how the power levels effect the emissions. It is well worth a read, even if its just a quick one.
https://oem.bmj.com/content/61/9/769
Hope someone finds this useful.
