Topband: N0OQW Beverage Spreadsheet

[Ford Peterson]

Many have requested and now received the spreadsheet that I used to outline
some musings on the 160 meter beverage "optimum" length.  I hope to receive
some feedback directly at ford@cmgate.com

The spreadsheet attempts to identify the difference between the wavefront in
air and compare it to the wavefront in wire.  By performing some calculus on
the resulting "difference" in phase, it occurs to me that the accumulated
difference shown on the chart as "optimum length" may need to be interpreted
differently.  Specifically, the peaks were selected as being the maximum
accumulated phase difference.  Instead, the length may be best predicted by
the point at which the accumulated phase difference crosses zero in the
data.

If this is true, the optimum lengths would then be:

Frequency 1.832 mHz

Vp        .98        .95        .90        .85        .80

1st       201        204        210        216        222
2nd       543        551        566        583        601
3rd       795        807        829        852        876
4th      1085       1102       1132       1166       1203
5th      1345       1366       1403       1441       1483
 
These measurements (feet) are the point at which the integral (indicated on
the spreadsheet as optimum) crosses zero, which is to say the accumulated
phase differences add to zero.

It is important to note that the lengths listed here extend beyond what has
been emprically determined to be "too long"  ON4UN's book reports diminished
signals when the beverage is too long (perhaps >1250' or so.)  It is also
interesting to note that the spreadsheet does indicate diminished
accumulated phase differences if you extend the spreadsheet out past 1500'
or so.

If you want an updated version, let me know.

Ford-N0OQW
ford@cmgate.com

P.S.  de W4ZV...The above lengths are very similar to the "cone of silence"
lengths described by W1WCR in his Beverage Antenna Handbook (290', 585',
880' and 1160').  See the following article by W3LPL for a nice summary:

http://www.eham.net/articles/503               


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