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View Full Version : which is better-electrical tilt or mechanical tilt ?



coursekec
2010-07-02, 01:14 PM
I am new to the RF world..can anyone explain me the difference between electrical tilt and mechanical tilt and it's advantages and disadvantages ? which is better if both options are available ?

EJAY
2010-07-02, 02:17 PM
Hi,
For young professionals you can read this simple handouts.
handouts attached for your reference.
No password.
just dont forget reps

Regards,
Ejay

pvbabu79
2010-07-02, 02:41 PM
hi

to my know ledge , electrical tilt is better than mechanical tilt

EJAY
2010-07-02, 02:48 PM
hi

to my know ledge , electrical tilt is better than mechanical tilt
no not really. it depends on the scenario!!!

striker
2010-07-02, 02:55 PM
no not really. it depends on the scenario!!!

i agree with you it's based on scenario..

banisha
2010-07-02, 10:57 PM
Depends of the situation, you can use even both!

adnansid
2010-07-03, 02:26 AM
I am new to the RF world..can anyone explain me the difference between electrical tilt and mechanical tilt and it's advantages and disadvantages ? which is better if both options are available ?

Mechanical Tilt:
Advantage: Decrease coverage and Does not add Interference as in case of Electrical tilts.
Dis advantage: Sector overlaps are increased.
Recommeded for sites which are very high.

Electrical Tilt:
Advantage: Decrease coverage and does not increase overlap in sectors.
Dis advantage: Increases interference, as portion of energy based on electrical tilts is trasmitted in the upper side lobe reducing the energy in lobe facing towards ground hence reducing coverage.

Recommeded for sites which are not very high.

onlygod
2010-07-03, 02:37 AM
Mechanical tilt will decrease coverage lengthwise from the sector, but in width, the coverage will stay the same.

Whereas electrical tilt decreases both length and width, like a circle on the ground which is getting smaller and smaller, but stays a circle. Whereas mechanical tilt results in elipse shape type coverage on the ground.

Mechanical tilt is used on tall sites, typically on top of hills, because electrical tilt is not enough.

Don't forget that mechanical tilt will lift up the backlobe of the antenna, so go easy with mechanical tilt.

Typically, in a city with a tall site, we might use 2 or 4 degree mechanical tilt with probably 4 or more degrees electrical tilt.

firstmaxim
2010-07-03, 04:53 AM
Electrical tilt is better for small amount of tilting, since it helps maintain pattern integrity and also curtail the backlobe. Mechanical tilting on the other hand has a larger range, but can induce beam splitting.

Regards.

Al_G9
2010-07-05, 04:48 PM
Hi:
Also M-Tilt increase the back loop which making interference in the back direction , we already using electrical at first then mechanical to reduce the cell coverage.:):)

gsm_forumer
2010-07-06, 03:38 PM
just wanna add my personal experience:
Electrical tilt also increase the VSWR value, Return to Loss, and Insertion Loss

so for equipment installation, I always test he VSWR before set the electrical tilt.

onlygod
2010-07-07, 12:52 AM
just wanna add my personal experience:
Electrical tilt also increase the VSWR value, Return to Loss, and Insertion Loss

so for equipment installation, I always test he VSWR before set the electrical tilt.

Can you explain with more information why does VSWR change with electrical tilt? I never heard of this before.

aosan
2010-07-07, 03:14 AM
Can you explain with more information why does VSWR change with electrical tilt? I never heard of this before.


me either....!! Can you please Explain. Thanks

firstmaxim
2010-07-07, 03:32 AM
Because the feed length is varied for the different dipole elements, it affects the characteristic impedence, and hence the higher mismatch, reflection and VSWR.

Regards

gsm_forumer
2010-07-07, 08:43 PM
don't know how to explain this, but this happened

year 2002, after finishing feeder cable + antenna installation, testing VSWR with result below 1.2
then, requested to set electrical tilt from 0 to 2
re-check VSWR, result become 1.3. troubleshoot resolve nothing.
replace antenna. set electrical tilt. check vswr over 1.3
set electrical tilt to 0, slightly above 1.2
re-set electrical tilt to 2, vswr again become over 1.3
by then my BSS Supervisor also confused, unable to explain why

leteo
2010-07-07, 10:21 PM
don't know how to explain this, but this happened

year 2002, after finishing feeder cable + antenna installation, testing VSWR with result below 1.2
then, requested to set electrical tilt from 0 to 2
re-check VSWR, result become 1.3. troubleshoot resolve nothing.
replace antenna. set electrical tilt. check vswr over 1.3
set electrical tilt to 0, slightly above 1.2
re-set electrical tilt to 2, vswr again become over 1.3
by then my BSS Supervisor also confused, unable to explain why

Hi Bros,

Anyone can clarify this acadamically ? :confused:

vinnybushkov
2010-07-08, 06:06 PM
Thanks for sharing.

vinnybushkov
2010-07-08, 06:29 PM
M-tilt: The antenna is tilted as a whole meaning all its segments are tilted.

E-tilt: Single segments of the antenna surface are virtually shifted against each other. It is realized by adjusting the phase of the control signals to the different segments electrically. The result is the virtual distance between the antenna back plate and each single segment varies so that an apparently tilted surface of the antenna front plate is resulting. Consequently, the antenna characteristic changes slightly if the electrical way of adjusting the antenna down-tilt is chosen. Since the virtual distance of the separate antenna segments to each other vary depending on the electrical down-tilt angle, the fading caused by destructive interference of electro-magnetic waves originating from the single segments is also shifted. Such an effect causes the antenna characteristic to vary depending on the chosen angle. Unlike the electrical down-tilt adaptation, the antenna characteristic is not affected if the down-tilt is varied in a mechanical way.

firstmaxim
2010-07-09, 01:00 AM
So, in effect we are tampering with the phase with which the signal is fed to the several dipoles, and also with the inter dipole gaps => resulting in altering the beam tilt.

Regards

iwanelits
2010-07-09, 01:52 AM
I am new to the RF world..can anyone explain me the difference between electrical tilt and mechanical tilt and it's advantages and disadvantages ? which is better if both options are available ?

Hi, I share to you how to describe differences between Me-tilt & E-tilt, you compile what the other said with the pictures....

Welcome to RFWorld :L

adeel
2010-07-09, 08:47 AM
Three kinds of methods and their combinations are usually used for antenna beam downtilt: Mechanical downtilt, preset electricity downtilt and electrically controlled downtilt (for electrically controlled antennas). During adjustment of the electrically controlled antenna downtilt angle, the antenna itself will not move, but the phase of the antenna dipole is adjusted through electricity signals to change the field intensity so that the antenna emission energy deviates from the zero-degree direction. The filed intensity of the antenna is increased or decreased in each direction so that there will be little change in the antenna pattern after the downtilt angle is changed. The horizontal semi-power width is unrelated with the downtilt angle. However, during mechanical adjustment of the downtilt angle, the antenna itself will be moved. It is necessary to change the downtilt angle by adjusting the location of the back support of the antenna. When the downtilt angle is very large, although the coverage distance in the main lobe direction changes obviously, yet signals in the direction perpendicular to the main lobe almost keep not change, the antenna pattern deforms seriously, and the horizontal beam width becomes greater as the downtilt angle is increased. A preset downtilt antenna is similar to an electrically controlled antenna in working principle, but a preset angle can not be adjusted.

kevin_h811
2010-07-09, 12:09 PM
I believe it's much better to isolate feeder cable from antenna so that we will not confuse which is which contributes low VWSR...

gsm_forumer
2010-07-09, 12:32 PM
I did..
try to measure the feeder cable with Dummy Load, resulting 1.1

perhaps need to check the antenna using Network Analyzer
but dont have both of them now (antenna nor NA), though I'm so curious.

ANTRF
2010-07-11, 07:31 PM
Hi Friends....

A document useful to understand ..

Analysis of Antenna Beam-tilt and Broadcast Coverage

By Myron D. Fanton, PE

Antenna beam tilt affects areas covered by strong signals. Improvements greater than 10dB are realized using greater beamtilts offered in end-fed arrays.

http://www.eriinc.com/pubs/WP22025.pdf

B.R.

ANTRF

d0000h
2010-07-14, 07:49 AM
don't know how to explain this, but this happened

year 2002, after finishing feeder cable + antenna installation, testing VSWR with result below 1.2
then, requested to set electrical tilt from 0 to 2
re-check VSWR, result become 1.3. troubleshoot resolve nothing.
replace antenna. set electrical tilt. check vswr over 1.3
set electrical tilt to 0, slightly above 1.2
re-set electrical tilt to 2, vswr again become over 1.3
by then my BSS Supervisor also confused, unable to explain why

Sure I suppose it is possible. However both VSWR are still acceptable and the difference between 1.2 and 1.3 is only 1.58% of your ERP (or 1/50th of 1dB) it doesn't seem like much of a problem to me. (someone want to verify my math?)

gsm_forumer
2010-07-14, 08:04 AM
technically acceptable

depend on customer, some of them requested VSWR below 1.2, so 1.3 won't get your work accepted

d0000h
2010-07-15, 02:22 AM
technically acceptable

depend on customer, some of them requested VSWR below 1.2, so 1.3 won't get your work accepted

Then I guess you would have to MDT the 2 deg. And if every antenna in his network reacts the same way to EDT, then you will no longer be able to use EDT.

So customer gets to choose:
1) Replace all antennas with ones that are still <=1.2 with EDT
2) Only use MDT and accept any QOS degradation
3) Live with 1/50th of 1dB of power loss.

Not a hard decision IMO.

-Deuce-

tremalnike
2010-07-15, 03:23 AM
Briefly, electrical tilt is better in all cases :time:
For details see Kathrein link above. If you need details see other document.
http://www.kathrein-scala.com/tech_bulletins/MEdowntilt.pdf

http://www.comnets.rwth-aachen.de/typo3conf/ext/cn_download/pi1/passdownload.php?downloaddata=70 - ps. download this *. htm file and open with pdf reader

BR

firstmaxim
2010-07-15, 03:57 AM
I am new to the RF world..can anyone explain me the difference between electrical tilt and mechanical tilt and it's advantages and disadvantages ? which is better if both options are available ?

Please find attached a paper on: THE EFFECT OF ELECTRICAL AND MECHANICAL ANTENNA DOWN-TILTING IN UMTS NETWORKS by Forkel and others.


Mechanical and electrical settings of the Node B’s antenna down-tilt in a single site scenario with three sectors are discussed. Concerning the %age of covered area under certain circumstances, the electrical adjustment of the down-tilt angle performs slightly better.


Regards

slavun
2010-07-15, 05:19 AM
And a variant without taking credits . Just Google it and it appears on 1st position. :)

http://www.eriinc.com/pubs/WP22025.pdf

P.S>
Nothing personal but I prefer to attach things which are hard to find in the WWW. The other way just post the link.

ANTRF
2010-07-15, 07:11 AM
@ slavun


You did not see that I had just posted the same link on this page?

B.R.

ANTRF

slavun
2010-07-15, 05:00 PM
Ooops, my mistake. Sorry.
The moderator can erase my posts.

mike
2010-07-19, 07:17 AM
Don´t worry,Thak you both for this useful link

indranil
2011-01-31, 05:26 AM
Hi,
For young professionals you can read this simple handouts.
handouts attached for your reference.
No password.
just dont forget reps

Regards,
Ejay


Hi Ejay,

Can u pls send the doc in my mail-id:indranilghosh83@gmail.com.
I am unable to download the attachment.
Pls share it , I 'll add the reputation.

BR//
Indranil.