Cross Polarization on 3G using Poynting LPDA 92

[Intell1gence]

Hi Guys,

It seems as though my post in the Poynting discussion thread is going to get lost, so i thought i might start a new thread for my question.

Currently i have a Poynting LPDA 92 antenna that im using on a Huawei E3131 usb modem on a rual location (no line of sight) and its giving me between 6-25% signal strength on Cellc/Vodacom roaming (WCDMA/UMTS/HSPA+).

As far as i understand one can greatly improve your LTE signal strength by using 2 antennas cross polarized.

1) I would like to know if i can get/expect an improvement on my 3G signal by using 2 antennas, cross polarized on a lte 3G compatible router (lets say the B315, as i think it supports 3G as well) or would i be wasting my money on the extra antenna and router (+-R2500)?

2) Does anyone have an idea of the time frame on when the sub 800mHz bands will be allocated for LTE, as that will surley benefit us in the rural areas!?

Thanks a lot!

 

[sajunky]

Check specs whether B315 maximum transmiting power is higher than E3131, then B315 will help. If not, in some conditions you can expect increasing of connection stability, but not a signal strenght, read more, not sure about it would help in your case.

Lets look what can happen when using dual antenna on 3G.

Tower can use MIMO in 3G. Standard allow it, but not it is not frequent locally. It would help doubling a speed in ideal condition, but not in your case (low signal condition).

With no MIMO a modem can still process a single stream independently in two channels, reducing number of dropped frames and retransmissions in that way. Would B315 do it? I don't remember whether any discussion in the past brought a resolution to this. There are also some techniques the towers use to improve reception that would reduce eventual improvements of dual modem. It is called beam forming. In short, a tower is adjusting transmitting patern individually for each client based on information coming from the modem. On the other side towers can deploy spatial diversity, then dual (not neccesary a single crosspolarised) antenna help. To which level? I don't know. It is more effective in urban areas.

You will be better of getting a dish (30dBi) antenna in remote areas. It may be illegal.

 

[Intell1gence]

Thank you so much for your detailed and insightful reply @sajunky !

Where can i start my search for a dish antenna?
Ive seen parabolic yagis online with better dBi but their frequency range is very limited, thats why i went with an LPDA.

Edit: Also what modem/brand of modem would you rather suggest i look into if i want to maximize my transmitting power? What is a good ballpark (i assume its rated in Watts?) to aim for?

Thank you again!

 

[sajunky]

I looked at spces it only says it is accordance to the 3GPP class 3, in both cases. It is a different on 2G though. Even it is the same, spec only says that device conforms to the given maximum power levels (meaning - not exceeding a maximum). What is a maximum power applied, we don't know, it could be lower for some devices due to the internal thermal issues. Small dongles had such problems in the past.

I think you should borrow B315 and test it in remote area where signal is weak before making purchasing decision.

 

[Intell1gence]

I looked at spces it only says it is accordance to the 3GPP class 3, in both cases. It is a different on 2G though. Even it is the same, spec only says that device conforms to the given maximum power levels (meaning - not exceeding a maximum). What is a maximum power applied, we don't know, it could be lower for some devices due to the internal thermal issues. Small dongles had such problems in the past.

I think you should borrow B315 and test it in remote area where signal is weak before making purchasing decision.

Thank you again @sajunky for your time and effort to help me.

I will see if i can maybe rent one from someone on the forum as i dont think i know someone close to me who has such a modem on hand.

I was thinking about your dish antenna proposal. What if i mount the LPDA on a dish (maybe a DSTV dish or probably a better suited purpose built dish like an Ubiquiti rocket dish, or a even a wok ) would this improve my reception?