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Type: Posts; User: davenn

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  1. Replies
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    Closed: Re: Question about RF power meter

    That is incorrect

    you have been told you need a Geiger tube for gamma rays as you are dealing with particles, NOT a RF or EMF emission
    X-ray detection is difficult, I am not sure a Geiger tube...
  2. Closed: Re: Where can I get my transmitter/microwave link tested

    You seem to have completely misunderstood the OP

    A 150W FM transmitter is not micropower by any stretch of the imagination

    The OP is trying to get his highly illegal, hence PIRATE,...
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    Closed: Re: RF Detector not detecting cellular phones

    They don't

    3G cellular uses spread spectrum, so it's quite difficult to pick up a signal from it as the TX signal aka RF power is spread over a wide bandwidth
    4G uses OFDMA multi-carrier...
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    [SOLVED]Closed: Re: 915Mhz Antenna design

    You say it is for transmission for 1 metre or less so there is no need for anything complex. A wire or a track on a PCB would be all that is required


    Dave
  5. Closed: Re: Monopole antenna is single ended or two terminal?

    have a look at all the examples here …….

    https://www.bing.com/images/search?q=monopole+antenna+on+groundplane&FORM=HDRSC2

    one example


    148355

    so the coax core goes through the ground...
  6. Closed: Re: Transmitter antenna for a particular frequency

    There is NO considerable amount of voltage received.
    The voltage induced into the harvesting antenna is uV (microvolts)

    it isn't useful for any practical purposes
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    Closed: Re: Design a Yagi with 4 to 1 Balun

    Yes, that is correct, but when put into a Yagi, as the OP is doing, its impedance drops significantly

    the 200 Ohm figure is quite a common figure used and a 4 : 1 balun to get to 50 Ohms

    That...
  8. Closed: Re: RF for Wireless Camera Flash Trigger

    do you really want to reinvent the wheel ??

    there are already many 2.4GHz remote flash units available out there and most of them would be much cheaper and better looking in smaller housing than...
  9. Closed: Re: Need clarification whether given project is low level or high level transmitter

    you haven't given any info with which to give a meaningful answer to your question
    do you have schematics for this planned transmitter and receiver ?
    what sort of power levels were you planning ?...
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    Closed: Re: questions to SATCOM antennas

    because that is how you get the required gain

    the higher in freq you go, the smaller the antenna needs to be to get the same amount of gain


    not sure ion the second question
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    Closed: Re: Would this transmitter work in reality ?

    that would probably be highly illegal and upset a lot of people !!
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    Closed: Re: Help need with simple FM antenna design

    if all you want to do is transmit the signal around the house, then you just want a 1/4 wave wire whip soldered onto the Antenna pad on the output of the transmitter

    a 1/4 wave at 108 MHz = 300 /...
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    Closed: Re: Multiple Access Techniqies

    google CDMA ( Code Division Multiple Access)
    this may help as your exact query is a bit unclear


    Dave
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    Closed: Re: sleeve monopole antenna

    no problems :) you are welcome
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    Closed: Re: sleeve monopole antenna

    hi there
    welcome to EDA Board




    Seriously ?
    there's plenty out there but the theory is dead simple .... here's an example with the math for you that I have drawn up
    ...
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    Closed: Re: opticalcommunication properties

    you really should learn how to use google ....... 100's of hits when I typed in your question .......
    ...
  17. Closed: Re: Cdama communication base station interferance

    here's lots of reading choices for you
    http://www.bing.com/search?q=explanation+of+cdma&src=IE-TopResult&FORM=IETR02&conversationid=&pc=EUPP_
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    Closed: Re: Antenna gain for silicon IC

    generally because the antenna dimensions are only a tiny fraction of a wavelength (at the required freq) and therefore have 0 or less than 0dB gain




    it still radiates, but not very well ......
  19. Closed: Re: UWB antenna with 500MHz bandwidth and 6GHz center frequency.

    at those freq's, you are probably right .... I did consider mentioning that but went with the LPY :wink:
  20. Closed: Re: UWB antenna with 500MHz bandwidth and 6GHz center frequency.

    a log periodic yagi

    http://wa5vjb.com/pcb-pdfs/LP8565.pdf

    a little bit of redesign will bring up the lower freq closer to 6GHz

    I have used several of his 2 - 11 GHz LP yagis and patch...
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    Closed: Re: dc loadline power amplifier

    it would help if we knew what transistor you are talking about and show a schematic of your circuit
  22. [SOLVED]Closed: Re: Why power is used to transmit signals through an antenna (not voltage or current)

    Do you understand what Power (Watts) is ? it equals volts x amps :wink:





    indeed, likewise,
    I think he? just hasn't quite put it all together yet ( the basics)
  23. Closed: Re: Realization of 22Hz transmitter by using magnetic coupling

    you have already been told once DONT be impatient and STOP making demands

    doing that is really going to stop people helping you ... no one likes being demanded to do things, specially for those...
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    Closed: Re: simple impedance bridge question

    maybe ideally, but in the real world it isn't likely to happen
    consider you have only been looking at the resistor values. What about the tolerances of the inductors and capacitors ?
    they will...
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    Closed: Re: simple impedance bridge question

    The 51 Ohm resistor could well be 50 Ohms anyway. a 10% tolerance is likely to vary from at least 45 to 55 Ohms anyway so you are not likely to gain anything

    same for your 27 Ohm resistor .... I...
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