Bouncing radio signals off the Moon? Yeah, but on 10 GHz?

Discussion in 'Satellite and Space Communications' started by VK7HH, Sep 28, 2019.

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  1. VK7HH

    VK7HH Ham Member QRZ Page

    Can you bounce radio signals off the Moon? Yes you can! What about up at a Super High Frequency such as the ham radio 10 GHz band. Well using WSJT and a decent amount of power, we attempted to do just that!

    KA0HCP likes this.
  2. AI3V

    AI3V Ham Member QRZ Page

    How about a summary of equipment used and results obtained for those who do not want to watch 14 minutes of video.

    WD4IGX, KD9NQC, AE8W and 1 other person like this.
  3. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Very nice setup. Thanks for the demo.
    VK7HH likes this.
  4. KL7AJ

    KL7AJ Ham Member QRZ Page

    The nice thing about such high frequencies is that you can get REALLY high antenna gain, which makes up for the challenges of getting lots of power at that frequency
    VK7HH likes this.
  5. VK7HH

    VK7HH Ham Member QRZ Page

    Very true! The gain in that dish coupled with 60W makes quite a bit of EIRP!
    K0UO likes this.
  6. WA9SVD

    WA9SVD Ham Member QRZ Page

    Probably enough to cook a chicken in a minute?:(:confused::rolleyes:
    AK5B, K0UO, VK7HH and 1 other person like this.
  7. SM0AOM

    SM0AOM Ham Member QRZ Page

    You do not cook a chicken with EIRP, but with available power, which still is only is 60 W.
    The opposite is just a myth, which is spread by people having shallow knowledge of electromagnetics.

    If the power density at the far-field or Fraunhofer distance at X-band from a 3 m diameter dish fed by 60 W is calculated, you end up with an EIRP of about 300 kW, and a power density of about o.5 W/m^2.

    The "rule of thumb" used for EMF safety assessment of microwave equipment using circular or square antennas is that the power density cannot exceed 4 times (available power/antenna area), at any point in front of the antenna.

    Antenna area is this case is about 7 m^2, and the power is 60 W, so the
    power density cannot exceed 34 W/m^2.

    A typical chicken has a mass of about 1500 grams, and a surface area of about 1/100 m^2, which leads to a possible heat transfer of about o.34 W per 1500 grams.
    Chicken heat capacity can be set as the same as water, for a first approximation.

    This leads to a painfully slow cooking, in the order of one month, even when assuming no other heat losses.

    Even if it by means of some miracle it would be possible to absorb all 60 watts by the chicken, the minimum cooking time would be in the order of three hours.

    Last edited: Sep 28, 2019
    N5YPJ, AI3V and WE4B like this.
  8. K6CLS

    K6CLS Ham Member QRZ Page

    The high gain antenna makes a very small beam, which can be difficult to point exactly on a 0.5 degree wide moving object.

    Doppler is huge on 10GHz. At least there's no Faraday rotation!

    All part of the fun.
    K0UO likes this.
  9. WA9SVD

    WA9SVD Ham Member QRZ Page

    Sorry,:( I WAS (at least a bit) being facetious. Our normal residential µwave ovens do operate in the microwave region, but (obviously) not with "EIRP" in the megawatt or greater region. The typical 1000 Watt (or less) power is normally confined within the oven enclosure, which does allow for quick cooking. (I.e., a baked potato in 5 minutes.)

    With that said, I have had a 600 Watt µWave oven for over 27 years, and it is still going strong, used at least once a day for making coffee, but often for REAL cooking for periods of 20 minutes or longer at a time. Maybe an anomaly?:rolleyes:
    Last edited: Sep 28, 2019
  10. AI3V

    AI3V Ham Member QRZ Page

    Yes, but what if the chicken in question is spherical in shape, and located in a vacuum?


    AK5B and K0UO like this.

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