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help, antenna for RF application in 868MHz

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Junior Member level 2
Feb 8, 2006
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hi, everyone,

i am working on the antenna design for a RF application in 868MHz. the read range is about 1 to 2 meters and the recived power needed to power the RF chip is around 100 microwalt.

which geometry is suitable for such antenna? i am considering the dipole, meander line and so on.

could somebody give me the suggestion? urgent!!!

thank you very much.

More information is required. Do you want 360degree coverage around the reader, 180degree coverage from a wall mounted unit or turnstyle, 2m in line with the reader?

what is the difference between 360degree coverage around the reader and 180degree coverage ? do you refer to the directional or omnidirectional antenna?

what is the difference between 360degree coverage around the reader and 180degree coverage
it's depends about the porpuse of your antenna, It will be used for?? 360º = Ommnidirectional. 180º = an specific direction you want to target.

the antenna is used in a RF smart sensor in 868MHz, which is similar with the RFID system.

the sleeve antenna also can be used~
the length is just 12 cm~

Hi Natalie,I'm also designing an antenna in this frecuency range.I had thought maybe meanderline could be a good option. But I'm not sure at all because i've read that printed antennas are not too efficient. Maybe an helix...

hi, Javirulo,

what is your project?

in my project, i was asked to design a uhf antenna for a rf smart sensor using sonnet software. i also consider to use meander line or dipole antenna. but i am definitely new in antenna design. i hope to get useful information in this forum.

keep in touch, maybe we can share the knowledge.

If you would like a printed small antenna try the koch dipole. It can achieve gain up to 7 dBi.
It is much smaller than the dipole antenna while having the same properties of it.

You can definately go forward with the microstrip antenna. It is very easy to control and fab. The common rectangular shape will work for you since the bandwidth requirement is very low (I assume that you work with the same bandwidth requirement as RFID).

there are lots of product you can reference. For instance TI's stuff is good

Try the koch dipole

Which type of the following is a better (small and high gain) printed RECEIVE-ANTENNA (line of sight, 20cm-50cm, 1.8GHz):
2) YAGI or Quasi-Yagi
3) printed dipoles or koch dipoles
3) printed log periodic

Thank you so much for your reply which will help me to limite my search on google.

Thanks for so many good comments. I think I got some idea now and can make decision . Thanks a gain.

nataliezhang said:
the antenna is used in a RF smart sensor in 868MHz, which is similar with the RFID system.
I have worked in RFID antenna design. The design of the antenna for RFID
is a little different in what the antenna is usually attached to the surface.
Having this in mind, the antenna could change dramatically depending of
the surface which it is attached. If your antenna for your smart sensor will
be isolated of any material and surface then I would say you have a lot of
freedom to choose. But if the antenna will be attached to any surface and cannot
be protruded then you have the same constraint than an RFID antenna.

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