[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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