What kind of antenna is this.

[mrpackethead]

Can any one tell me what kind of antennas these are?   They are for 900Mhz..   

[T3sl4co1l]

Probably https://en.wikipedia.org/wiki/Collinear_antenna_array

[bjcuizon]

Probably https://en.wikipedia.org/wiki/Collinear_antenna_array

Yup, probably for gsm/mobile com antenna arrays.

[hcglitte]

To me they look like end fed half wave dipole antennas.

[LukeW]

Are the wider cylindrical pieces 80mm long, or so?

It just looks like a good old half-wave dipole.

[cdev]

I think it may be a collinear but because the gaps between the wider sleeves, are not 100% consistent with what I would expect, its hard for me to say 100% unless you can give us images with more detail.

The closer images look more like sleeve dipoles, the ones in the upper rear part of the picture are more likely collinear. Its probably collinear.

[mrpackethead]

Im guessing i'm going to have to pull apart the antennas i have to find out for real! these pics are taken from a factory in china...

[PA0PBZ]

Looks like stacked dipoles, the bigger parts do seem to have a hole or even a circle around them in the middle.

[cdev]

This is a coaxial collinear antenna, you can see the difference-
http://www.nodomainname.co.uk/Omnicolinear/2-4collinear.htm

Its likely possible to make one with sleeves, but its not so clear to me yet how they'd handle phasing...

does anybody know?