External Antenna

[torex]

Bros, could anyone explain why sometimes we need to use external antenna for DT..? what impact for real customer experience?

TIA

[gprastomo]

Bros, could anyone explain why sometimes we need to use external antenna for DT..? what impact for real customer experience?

TIA

Hi,
as i know, the use of the external antenna to measure outdoor coverage and usually it will be compared with coverage prediction which is predict the outdoor coverage so the use of external antenna is mandatory to compare with coverage prediction.

If there is no external antenna so there will be body loss or car loss etc which will be added to path loss

br

[rikoto000]

Bros, could anyone explain why sometimes we need to use external antenna for DT..? what impact for real customer experience?

TIA

In a drive test scenario using the ordinary phone antenna it is considered as an indoor or inside the car testing (with losses)... By using the external antenna we can test the Radio Interface outside the car and producing a much more reliable outdoor testing experience.

[da_manole]

Bros, could anyone explain why sometimes we need to use external antenna for DT..? what impact for real customer experience?

TIA

The omni antenna has no directivity.When you keep the phone in the car you have directivity. If you have the site in front of you ,you will have a level and if is behind you the difference will be 7-10 db.

[torex]

Thanks bro, but in real situation, the customer is inside the car!, could you explain that?
TIA


In a drive test scenario using the ordinary phone antenna it is considered as an indoor or inside the car testing (with losses)... By using the external antenna we can test the Radio Interface outside the car and producing a much more reliable outdoor testing experience.

[naga30]

Dear torex

Yeh sometime customer needs external antenna reason of site is overshooting anther far area or they like to reach rf remote area.

BR
Naga30

[hassen]

Bros, could anyone explain why sometimes we need to use external antenna for DT..? what impact for real customer experience?

TIA
Hi
external antenna mean the ability of the transmitter to pass energy from its antenna to free space,similarly the same is true of a receiver.
about your question..
If the phone still works lying on the table - so what happens?
As you know In theory a horizontal receiving antenna will receive no energy from a vertical transmitter antenna it means the signal from the transmitter strikes many objects along its way and is reflected from them, these reflections are often twisted because of the irregular nature of the reflecting object
By the time the signal reaches you it has lost much of its initial polarisation and become scattered.
However it will usually still be the case that most of the signal will maintain its original polarisation and the more vertical you keep the antenna the better your chances of a good signal.

br hassen

[parto_tegal]

Hi
Usually, the external antenna to be used on Drive Test measurement is having 0dbi gain (omni antenna), to reflect the measurement result as purely "outdoor" (not affected by car body absorption, etc).

Unfortunatelly, some vendor uses some +3dBi antenna to cheat the operator of better measured performance compared with the real condition.... So what?

Regards,
parto_tegal

[mirza]

Bros, could anyone explain why sometimes we need to use external antenna for DT..? what impact for real customer experience?

TIA

Hello all

I think one reason for using the external antenna with scanner is to measure of RSSI / Ec totally as Transmitted by antenna.Because in UE the measured power is considered with the Device antenna losses.

and with the help of this we can accurately find out the sc's, Ec, Io, RSCP with respect to ideal conditions. which can allow us to have an idea about device losses.

Thanks

Mirza

[elche]

when you do a drive test you want consistent results, for example we have a vehicle with tinted windows, for some reason if you measure inside you will notice a 10-15 db difference. Meanwhile we have a car with untinted windows and we measure around 4-6 db difference if compared to the outdoor signal. I'm also sure that you will have a different signal strength loss inside a hummer than inside a golf cart. So what happens if you swap vehicles? two areas with exactly the same signal levels or a second drive test with a different car could show a dramatic difference and could mislead you to think there is a problem with the cell coverage. Also , unless you use a car holder there is no guarantee the phone will always be in the same exact position making the measurements even less reliable, and again the car swapping problem also applies since unless they are installed in the same exact position the will be differences in the readings. So to make the results consistent we take measurements using standarized methods (0 dbi antenna) and then apply average or "typical" losses , such as indoor penetration, car penetration loss to a single number that will give us better idea of the expected coverage in different situations. BR

[torex]

Bro, if you mean to get "pure outdoor" with 0 dbi antenna gain, could we get it? as i know we will have cable and connector loss. Am i right?


Hi
Usually, the external antenna to be used on Drive Test measurement is having 0dbi gain (omni antenna), to reflect the measurement result as purely "outdoor" (not affected by car body absorption, etc).

Unfortunatelly, some vendor uses some +3dBi antenna to cheat the operator of better measured performance compared with the real condition.... So what?

Regards,
parto_tegal

[elche]

0 dbd are special purpose antenna and are calibrated to have a total gain of 0 dbd including cable/connector loss. so the tip will have a small gain to compensate the cable losses. If you need more technical info you can search for Smarteq minimag 1140.26 and 1140.27

as always reputation is welcome if it helped
BR

[da_manole]

Hi
Usually, the external antenna to be used on Drive Test measurement is having 0dbi gain (omni antenna), to reflect the measurement result as purely "outdoor" (not affected by car body absorption, etc).

Unfortunatelly, some vendor uses some +3dBi antenna to cheat the operator of better measured performance compared with the real condition.... So what?

Regards,
parto_tegal

The drive test it's done for tunning or testing the network.If you know the Outdoor level(means what you will measure with an omni antenna ) you will know what level of service will be in that area .for example if is -88 you can say that it's outdoor if you have -82dBm incar ...-70dbm indoor....These levels depends on technology ,frequency ,margins...
If your antenna it's with 3 dBi gain you should use the value when you calculate the link budget.A good antenna phone it's -2dbi.a wrong one can be -10.

[ozcank]

thank you so much your useful sharing ;)

BRs,

[gigel]

so many ideas, let's have mine too :)

1.The base line - predicted/simulated network coverage, that usually is referring to Outdoor coverage
2.Network/coverage check - drive test, normally is measured also in Outdoor conditions

Why to cheat the Operator?! This is wrong! On the contrary the Vendor need to reserve a margin as a guard for him self, otherwise the Operator Marketing/Sales department will perform Bad Sale action and will end up with customer complaint in low signal :) and judge Vendor for this!

Drive test with Omni-Directional magnetically/car Antenna on top of the car (as normal way)
- 0dBi with feeder and connector (can have -dBi is the terminal mini RF Jumper or terminal to antenna adaptation is not so good)
- if is improper used you can get more or less a directional characteristic. Ex. if the antenna is placed in the middle of the car rooftop is not the same if is on the edge of the car rooftop more to back or to the front of the car; check the manufacturer specifications. There are rules about how to place more antennas on one car rooftop for a very rigid test scenario.
- you will get an image of the signal level in Outdoor, compare with simulated/predicted coverage and compute easily the type of coverage in that place as Indoor, Incar or else
- use identical drive test kit and car setup for all drive test teams

Drive test with test terminals placed Incar (terminal antenna)
When the drive test with outdoor omni antenna is not possible it can be done with test terminals placed Incar, but you need to take care about some things:
- use identical drive test kit and car setup for all drive test teams (place terminals in same position and fix them in a phone holder)
Pay attention because will not be the same signal inside the car if:
- if you have a open (one which side) is not the same with all windows closed
- how many persons are in the car and where they are in the car
- if your direction is to the site is not the same if you go away from the site
- take in the account also the car penetration loss and perform some test to get the real value for your particular case (same place, Incar vs. outdoor measurements for few minutes). In order not to have on the same location some measured points with really different values, in post-processing use location binning and benefit form the location aggregation.




thanks you,

[dexterhaba]

simply because you want to measure signal more accurately ,, rather than inside the car that can have various effects due to car penetration loss....