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Help me design a very small 2MHz antenna

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acbalbason

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hi!

i'm trying to make a transceiver with everything as small as possible. i'll be implementing it in 0.35 um 2P4M process. any antenna suggestions? my friend told me to look up for directional antennas. any suggestions? i was aiming first for rfid but 2MHz is quite low for rfid he says. any help?

- al
 

Re: 2MHz antenna

At 2 MHz, you can use a ferrite antenna. It is a small bar of high frequency ferrite material around which copper wire is wound. A capacitor is used to resonate it, so you can make a tradeoff of efficiency vs size (ie make the ferrite bar small but more lossy).

**broken link removed**
 

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    acbalbason

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Re: 2MHz antenna

hi!

thanks for the help! i don't know how i can possibly do layout with ferrite. i'm just using standard cmos pocess for fab. any structures you can suggest? Ü

- al
 

Re: 2MHz antenna

Hi
I think 2MHz IC transmit antenna will be not effective
Size is needed to transmit effectively
 

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    acbalbason

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Re: 2MHz antenna

hi!

really? it is a challenge though. i only know of rfid ics because the smaller the chip usually it operates at higher frequencies. i need mine small by operates at a low frequency. i really need help in this. i'm implementing it first with discrete components. at least any suggestions on that one. i'll work out the ic part after successful implementation with discrete components.

- al
 

2MHz antenna

some rfid according to iso18000 operates even lower .. in 125khz, they are using coil antenna but with very small range.
 

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    acbalbason

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Re: 2MHz antenna

Hi, you can see if helix, spiral or fractal antennas which usually can save some space for you with acceptable performace especially for rfid antenna at 900 MHz, although a modified dipole can also save that purpose.
 

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    acbalbason

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Re: 2MHz antenna

As you increase your frequency of operation, you will be able to widen the range of transmission, and that would be somehow better (it depends of course on your application)
 

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    acbalbason

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Re: 2MHz antenna

hi guys!

thanks for all the help! i'm sorry if i ask too much. i am a microelectronics major but not well versed in antennas, transceivers, etc. range is not a major factor. i just need a foot or two. i'm developing an implantable transceiver. i plan to make it a passive rfid tag so battery space is scrapped to make it more compact. is it possbile for me to make a chip transceiver? considering it's soc. i have a dsp planned to be incorporated with the transceiver.

- al
 

Re: 2MHz antenna

Well, 2 mhz might be a good frequency if it is actually implanted inside of a body. About the highest I might go with such a system is 8 MHz. Much higher and the salty flesh of the body will stop signals from penetrating out.

You will have a lot of trouble radiating from an antenna, since a quarterwave at 2 MHz is thousands of times too big for your application. I would print an on-chip inductive loop around the periphery of your IC chip, and drive it with a current source transmitter. Properly done, the current source transmitter might run off of a very low voltage supply, like maybe 1.2V dc. The transmitter loop would NOT be resonated at 2 MHz.

Then I would use a much larger receiver loop antenna, with lots of turns and tuned to that 2 MHz frequency. Maybe a 2 foot by 2 foot receiver loop? That should get you a few feet of transmission range.
 

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    acbalbason

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Re: 2MHz antenna

hi!

2 foot by 2 foot loop? quite big. i was planning also on making a similar transceiver outside the body. to scan the data given by the chip inside. quite a challenge huh? hehe.

- al
 

Re: 2MHz antenna

hi!

hehe. yup, a ferrari is cool. if i make an antenna smaller, like ic size can i shrink the transmission distace to a few mm? i only need a small distance to transmit and receive.

- al
 

Re: 2MHz antenna

check out fractus.com for some very small miniature antennas. This is word of mouth. I haven't seen it myself but have heard that they have very small chip antennas.
 

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    acbalbason

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