For those people who are suffering from low signal strength resulting for making ur day worst. haha
Please note that "do this at your own risk". This may result undesirable result if u fail to follow what i did.
This actual pics are taken during my applications.
What i did here i opened my ZTE MF627 dongle & disassembled it.
**i also tried to open my other(huawei and telkomsel) 2 dongle i check it and they look the same manner..
Stuff you need before dissecting ur dongle.
1. Precision flat screw driver or small flat driver that would do. *I prefer sharp flat screw driver.
2. Precision philip screw driver.
3. cutter knife & other basic electronic stuff *too many to mention.
4. wimax outdoor antenna with male & female coaxial cord.
5. initiative!
6. Large amount of Guts!! *hehe 
so after unwinding all screws, slowly opened the kit & separating all the parts.
This is what i got.

i remove the built-in antenna..take it off..
*where is the built-in antenna?? --the arrow is pointing at it..
[IMG]http://4.bp.blogspot.com/_hiYJA40GV3o/S_kUoWs72UI/AAAAAAAABDY/fF4NCFC1D9Q*******DSC02467.JPG[/IMG]

after i remove the built-in antenna and i solder coaxial cord of the wimax antenna..
why use the wimax antenna?? why cant use tv antenna in cdrking, BALUN antenna, BARON Antenna or any other antenna??

**wimax antenna operates at 2.4ghz with 14dbi its design to harness this kind of frequency
for WCDMA, HSDPA, UMTS & even 4G. This antennas are also known as hi-gain antennas.
so if you try make your own antenna that would make undesirable result due to the impedance of your antenna aren't match to the input impedance of your kit a.k.a mismatching impedance & may lead to bounce-back the signal sent of ur dongle causing overheat of ur usb kit or even worst.
--in short making or using other antenna ain't a good idea.

palit pud mo ani sa electronics shop.. kani dapat gamitun..click here to know more about coax wires.
pra nice pd tan.awun inu work. coaxial cord header male and female..
then dara final outcome akoa binuhat.. naa pigtail hehe pro ako nani g.pa.muboan ug maau pra dli samok tan.awun.
**yes!! sakto ka---, ako g.bangagan akng kit pra adto nko ipalusot ang coaxial cord..
**tarunga lng pd ug bangag ninu na angayan pud tan.awun..

then i installed the outdoor antenna.
[img]http://4.bp.blogspot.com/-f0qobJbYDIs/Tb3muYw5CFI/AAAAAAAAAD8/lHykpytgq3Y*******near_line_of_site.jpg[/img]
**For better results if there is a cellsite tower u can see on ur rooftop upon installing ur antenna.
Face ur antenna to the cellsite if possible make it line of sight to cellsite tower & ground ur pc to earth..
And here is my result #char haha.
NOTE: It's must to remove the built-in if you want to install another antenna to your dongle to prevent mismatching of impedance.
Unlike some other dongles it has already CRC09 female connector where you can directly plug its antenna and automatically disable its built-in antenna.
*
UPDATE: There are hi-gain antenna same specs of wmax antenna at cdrking. That antenna intended for wifi antenna & i think that would do for this applications.
dont use the antenna during lightning.
Gudluck guys..
ps: actually this dongle were already sold because of its feature haha..
its openlined and you may use antenna if u want to..its firmware were reflash to 7.2mbps 3G.
no guts no glory..
sharing is caring..