What is the stepper motor used for in RET?

[wolverine]

Hi guys,

I am not really a HW guy, hence the question..

As I understand Electrical tilt adjusts the phase of the dipole elements within the antenna to direct the beam.

When reading about RET (Remote Electrical Tilt) there is mention of a stepper motor. If Electrical tilt does not physically move the antenna what is this stepper motor used for? :confused:

thanks

[dimooon11]

Antenna with adjustable electrical tilt has a positioning rod which you can adjust manualy (get to the antennas, remove protection cap beneath antenna and turn the rod in desired position=el.tilt) or use remote control.
RET system consist of control device and unit with stepped motor connected to positioning rod. For purpose to physically turn this rod you need stepped motor.

RET usually used during optimization project when excessive repetitive antenna tilting may be needed to meet requirements.

[salmeterol]

in the bottom of antenna, you can see two adjustable rods, one mechanical tilt aparatus other electrical tilt aparatus.
There are numbers on those rods.
if you want to give downtilt from 6e to 8e, you will take the rod from 6 to 8 value. thats all.
stepper motors are doing same job remotely.....

:-)

[wolverine]

So the "electrical" part of RET actually means physically tilting the whole antenna remotely, and it is not the same as "electrical tilt" which refers to phase adjustment of the dipoles within the antenna?

[dimooon11]

So the "electrical" part of RET actually means physically tilting the whole antenna

No.
Electrical tilt really means phase adjustment of the dipoles.
But how antenna knows that you need phase adjustment? :lol
There is an adjustment mechanisms at antenna (adjustment
rod or wheel) that you need physically adjust and then dipoles make phase shifting.

Refer to the picture below. Hope it'll help you to understand better.

http://img7.imagevenue.com/loc11/th_704779934_tilt_122_11lo.JPG (http://img7.imagevenue.com/img.php?image=704779934_tilt_122_11lo.JPG)

[ritgail]

Wolverine,

the stepper motor is a special type or rather i should say a precise motor. This motor does not rotate like regular motor where you have +ve and -ve, connect it and it will run, disadvantage you cannot control the speed and the exact position. With stepper motor, this is possible--where the rotor rotates at precise angles when given a pulse, you will find upto 8 input wire...this kind of stuff is used in printer, scanners, plotters, robots you name it.

see this Stepper motor - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Stepper_motor)
a project with any 8051, search google..
I found a RET product
Powerwave Technologies | Remote Electrical Tilt (RET) Products | RET Modules (http://www.powerwave.com/remote-electrical-tilt-modules.asp)
they are saying its configurable, i doubt they are using the 9600 serial port of bts which is in turn go the E1 and you can monitor or do anything...

(E******* expert pls give a light on the 9600 baud rate port of BTS)


the electrical tilt, as you know you have to move the rod mechanically to achieve the desired rf lobe to cater coverage, which has to be done by a person, you need to engage manpower, means cost..and this is not fast..
by employing the stepper motor mechanism attached to the electrical tilt rod, you can precisely make the angle.....if you can do it remotely then you are making very fast optimisation... :D