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Recent content by ElCap

  1. ElCap

    180 degree Hybrid Coupler for rfid application

    yeh thats cool Thanx everyone for your help with this!! 1 problem done, plenty to go!
  2. ElCap

    Rf Power Amplifier

    oem - original equipment manufacturer? well the company were buying the tags from is gonna give us a demo of their system. They sposedly get an EIRP of 36dBm, 4W, which is the power limit in aus for 915mhz. so ill find out what type of amp their using cos i cant seem to find a amp chip and we...
  3. ElCap

    Rf Power Amplifier

    also we are using passive tags so it doesnt have a power source, so therefore needs power from the reader to work.
  4. ElCap

    180 degree Hybrid Coupler for rfid application

    i havent actually heard of a 0db coupler. and cant seem to find one thru googling either
  5. ElCap

    180 degree Hybrid Coupler for rfid application

    so how is power split up between the ports with a zero db coupler? i spose the transmitted power will go straight thru to the antenna, but will the received power get to the receiver?
  6. ElCap

    Rf Power Amplifier

    well the transmitter puts out 5.5dBm (-24.5dB) and the our tag sensitivity is .5mW (-3dBm) and we have a path loss of approx 35dB. so we approx need about 30dB gain to reach the tag. i see what ur saying bout the total output, ve1bll, i sorta wondered why that was on the datasheet lol! as for...
  7. ElCap

    Rf Power Amplifier

    hey im designing a rfid system for a project at 915MHz im getting 5.5dbm out of the transmitter and need approximately 35dbm out of the antenna to compensate for the free space loss and to reach the tag 2m away. Therefore i basically need a 30db amplifier. the only thing is i cant find a 30db...
  8. ElCap

    RFID Patch antenna

    are u talking bout a 1/4 wave microstrip patch? cos i know how to make those (sort of). i was sorta asking bout a 1/8 wave one. is that possible?
  9. ElCap

    180 degree Hybrid Coupler for rfid application

    so am i thinking too complicated about this? so just a normal coupler will work? will the coupler be able to pick up the received signal and couple it to the Rx even thou its alot smaller than the transmitted signal?
  10. ElCap

    180 degree Hybrid Coupler for rfid application

    well i found out that the coupler works in both directions (duh), which makes more sense. our system is half duplex which i thought works with the transmitter and receiver operated at different times to each other, but in fact the transmitter is on all the time. it sends a carrier wave whens it...
  11. ElCap

    RFID Patch antenna

    yeh i was including the ground plane as well in my calculations but yeh i was exaggerating a bit. how would i go about making a shorted patch? what changes would have to be made to the design with respect to the basic 1/4 wave microstrip patch design? any specific websites or material you can...
  12. ElCap

    180 degree Hybrid Coupler for rfid application

    the rfid systems that operate on different freqs are the ones that use inductive coupling as there means of "talking" to the tag and the return signal is double the freq of the transmitted. but for 915mhz inductive coupling cannot be used and backscatter coupling has to be used.
  13. ElCap

    180 degree Hybrid Coupler for rfid application

    Hey guys, im designing and creating a rfid system as a project with a few friends. i have the task of designing the reader antenna. the antenna part of this proj is being discussed further but the point of this post is to get some info on directional couplers. ive been informed that we will...
  14. ElCap

    RFID Patch antenna

    yeah its for a reader antenna. and yes we do have access to a network analyzer and antenna test equipment. been doing a few calculatuions for it and it seems that for a patch antenna at 915mhz that it would be about 30cm X 30cm, which is a bit big for our application. ive heard about a...
  15. ElCap

    RFID Patch antenna

    Hey guys, im designing and creating a rfid system as a project with a few friends. i have the task of designing the reader antenna. were operating at 915MHz and i was gonna design a patch antenna on a pcb as its simpler. What software is there to design this kind of antenna? (freeware would be...
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