Connect with us

2.4GHz absorption by plastics

Discussion in 'Electronic Design' started by martin griffith, Jul 16, 2007.

Scroll to continue with content
  1. joseph2k

    joseph2k Guest

    Maybe, maybe not. Microwave absortion is very frequency specific (molecular
    resonances). Microwave oven characteristics (typically 2160 Mhz) may not
    translate to WiFi bands, just a few hundred Megahertz away.
     
  2. Yes, the absorption is frequency specific. However this specifics shows
    up at the frequencies of tens of GHz. It is irrelevant to microwave ovens.
    Huh?
    Microwave ovens have nominal frequency of 2450MHz (actually they
    generate a pretty wideband splash). This is the same ISM band that used
    by WiFi, Bluetooth and such.


    Vladimir Vassilevsky

    DSP and Mixed Signal Design Consultant

    http://www.abvolt.com
     
  3. joseph2k

    joseph2k Guest

    Hmmm. There is no frequency data on the nameplate of my kitchen unit, so i
    did some searching. And there they are at 2450 MHz right on top of 802.11g
    channel 9. The 2160 came from the nameplate data of the last microwave
    oven that i saw that had a frequency specified.
     
  4. Guest

    FYI, alt.internet.wireless discusses this topic often.

    I prefer the biquad antenna, which you can augment with a dish. I have
    a short-cut method to build this antenna. With a combination of these
    photographs and this link, you should be able to figure it out.

    http://martybugs.net/wireless/biquad/
    http://www.lazygranch.com/images/wifi/wifi_bq_1.jpg
    http://www.lazygranch.com/images/wifi/wifi_bq_2.jpg

    Note you don't need to make the loop a square. Use a circle of the
    same circumference.

    There is a disadvantage to using the helix. It will receive both
    horizontal and vertical polarization. Most sites just send in one
    polarization. In busy areas, the same channel will be used in
    different sites with different polarity. Now if you use the helix to
    illuminate a dish, then the circular polarization is fine and perhaps
    desirable. That is, you could sniff out signals without the
    attenuation associated with having the wrong polarization.
     
  5. Chris Jones

    Chris Jones Guest

    That's in the 2110 - 2170 range that is allocated to the downlink signal of
    UMTS (3G) mobile phones in many countries. Those frequencies were sold for
    a price that people found surprisingly expensive at the time.

    Chris
     
  6. On Sat, 21 Jul 2007 11:41:41 -0700, in sci.electronics.design
    Thanks Miso, I'll start lurking there.


    martin
     
  7. Rich Grise

    Rich Grise Guest

    It's also plop in the middle of S-band, which is loaded with military
    radars, and there's an ionospheric window there so there's a lot of
    demand for uplink/downlink channels.

    Cheers!
    Rich
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-