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@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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