[CQ-Contest] The short-sighted analogy

[i4jmy at migate.ampr.org]

    Very often the analogyes are rather incorrect, but this lack of
  precision gets an "acme" when talking about contesting.  
    Human or car races can't explain a complex situation, the amateur
  radio contest, were the competitors are finally playing a different
  game because placed in different locations and dealing in different
  situations.  
    Each experienced contester should have this fact well clear in his
  mind and who has not experience yet, should start to think about it
  seriously not to get disappointed then.
    Everybody aiming for results in contesting should know at least the
  minimal basis of short wave propagation, the WPX debate is clearly
  showing this is not always true.

    Short waves can't reach all the points of the world following the
  earth surface or by a single ionospherical reflection.
    The shape of our planet, the respect of trigonometrical laws, and
  the phisical features (limits) of the reflecting media are the
  unavoidable elements to deal with.  
    Latitude and other geo/geomagnetical situations often make things
  even more complex and peculiar, but this is out of this speech.
  (btw, a reading of some book extensively threating about propagation
  is always recommended) 
    In any case, to reach a distant point, a radio wave has to be
  reflected one or more times by the ionosphere and each of the "hops"
  causes an attenuation of an average extimated 10DB extra (added) to
  the inherent path loss. 
    A second ionospherical reflection include also a reflection by the
  earth surface so, 1 hop is 10DB but 2 hops is 30DB. 
    As a remind, 10DB attenuation means that only 10% of the original
  power is left, 30DB that the left power is only 0.1% . 
    If a little 2-3 DB could make to copy or not, an extra 20 DB is an
  enormous amount, often impossible to be overcomed.  
    Unfortunately the above situation it is not the worse possible,
  infact, lowering the used frequency, the reflection by the ionosphere
  takes place only when the incident angle gets bigger so bringing not
  to a add another single hop, but often to add a number of extra ones 
  in order to reach a stated area.

    The above clearly fix one point, who need more hops for a stated
  path not only suffers by shorter openings, but mainly is subdue not
  to receive or not to be received by a great percentage of stations.

    It's easy to realize why a W6 who has never been in W1 or in Europe
  can't believe how big is the europeans number, likewise a western
  european can't have an idea of the W6 or JA population.  Another
  logical deduction is that in low flux conditions, when there is no
  alternative to a low band use, this differences are enhanced and the
  opposite is true when sun spots give 10 meters suitable for contacts.

    This also explains very well why reasonable similar (effective)
  pile up's are possible both east and west coast USA to Europe on 10
  and 15 meters (angles as low as 2 degrees reduce the required hops to
  few unity), while it doesn't exist on the lower bands even if using
  monster monobanders in one of the 2 edges.


    
  73,
  Mauri I4JMY (one of IR4T)

  e-mail i4jmy at migate.ampr.org




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