[TowerTalk] Modeling vs Experimenting

[Jim Rhodes]

Experimenting can give you an antenna that works well, modelling can tell
you why (and even how to improve it).

Jim Rhodes
K0XU

On Thu, Sep 12, 2019, 08:26 Jim Thomson <jim.thom at telus.net> wrote:

>   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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