On 8 Feb 2005 18:49:05 -0800, wrote:

+1 dB was what our theoretical
difference was, but it may have been more.


First the average reciever will not see the differnce unless right at
the threshold of detection (MDS). The only place I've seen a 1db
difference that was detectable is in really weak signal systems.
In those systems the 1DB differnce cosses the threshold from just
noise to marginally detectable. Such as EME or my favortie mode
troposcatter.

The average FM broadcast system TX and RX runs at high power because
the average FM rx has limited sensitvity due to the required wide
bandwidth. Those recievers require a much larger signals to hit an
acceptable signal to noise and rarely can differentiate between
a 1db difference.

Sorry, but we don't have a huge VHF anechoic
chamber, and the proper signal strength meter
to do this properly!

Measuring 1db difference does not require all of that. As to a
propper field strength meter, specify a brand. They are not rocket
science and are easy to build. If you really want to see something
attend a Central states VHF society antenna gain test. They usually
hit .1db or better accuracy and have tested Jpoles. The results of
past years are posted at their site.

http://www.csvhfs.org/CSVHFANT.HTML

I'll point you to the 2004 results and specifically to the 144mhz
section where a Jpole entered scored a -2.8db gain compared to
a reference dipole (0db)

These things are easily tested and easy to verify. If your trying
to resolve to bettern than .1DB that may be harder but,
3DB is easy and tends to jump at you.


Allison