[TowerTalk] Modeling vs Experimenting

Jim Thomson jim.thom at telus.net
Thu Sep 12 09:26:41 EDT 2019


  I use  both  methods.   The problem being in a residential  neigbourhood is I am surrounded  by  other  homes, some  with well  grounded wire mesh
below  stucco  siding,  then the  usual myriad of   neighbours attic +  house  wiring, copper  plumbing,  then  miles  of  single and  3 phase  commercial AC  power,  utility poles,
lamp  standards,  sloping ground, trees,  miles  of  asphalt streets,  concrete and  asphalt  driveways, hundreds  of metal  cars. Miles of telco  and  cable  company lines. 
And soon  to be installed   5G  network....  with  ants  mounted every   100-300  yards.   One  nearby  home  just installed a ton  of  solar panels.   Some homes  are  now installing
metal roofs. 

How  do  you propose how  to  implement HFTA  with  the above ???     Loads  of  clay below the pristine lawns too.   Forget the  lousy  ground  for  a minute, there  is  so much junk 
in  the nearfield, and farfield, how  can  any  software even begin  to factor a fraction  of these  extraneous  items?   Same  deal  with  nec2 and nec4.   Sure, the  say  proposed  yagi,  etc,
can  be  designed  in  free space.... then  modeled  above sloping... poor to average  ground.   Good  luck  with  trying to  correlate  software  results ...with  reality.      Trying to  compare 
RX  + TX signals  with  nearby hams is an exercise In futility.   One  night  Im louder, the  next night,  local  buddy  is  louder.  Change  directions,   and it all changes  again.   Change  bands,
and its a whole new  ballgame.   Huge  differences  in  band  condx, when  trying to  compare  with  stations  100  miles north of me. 

They  have a sign up at NASA  that sez......  one  test  is  worth a 1000  opinions.      Want  to see how good  your  CM  choke is, measure the  RF  current  with a clamp on  RF  ammeter  in  several
places  on  the  coax,  then again around  the  home and shack, plus  misc  stuff.   Then  swap  CM chokes, and repeat the  test.  Its a eye  opener. 

Later....  Jim  VE7RF


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