[BC] Vertical or Horizontal

[Mark Humphrey]

On 12/6/06, Phil Alexander <dynotherm at earthlink.net> wrote:
 most of the time.
>
> Turning the clock back a tad over 40 years, that was given,
> at the time, as the primary reason for adding V-pol to an
> existing H-pol signal in the day when nearly every station
> was strictly H-pol.

In 1967, while he was Assistant DE for Triangle Publications (Walter
Annenberg's media empire), my friend Lew Wetzel wrote a NAFMB paper
entitled "Practical Experience Derived from Dual Polarized FM
Antennas", discussing the results of experiments conducted at WNHC-FM
(now WPLR) in New Haven/Hartford, CT.  I have a copy here which has
been converted to PDF, it should be posted on my website next month.

He concluded the following :

A: In the absence of shadowing or diffraction effects
transmission of a vertically polarized component
adds very little to the signal received on a horizontally
polarized receiving antenna.

B. When receiving antennas having a substantial vertical
component are employed, a correspondingly
substantial improvement in over-all service can be
expected.

C. The vertical component appears to have substantial
value for users of automobile FM radios and portable
FM receivers.

D. In the presence of shadowing or diffraction effects,
spots which have very low signal strength when
horizontal polarization alone is transmitted, tend to
find a substantial improvement in the horizontally
polarized component of the field in such shadowed
areas.

I had lunch with Lew a few weeks ago and told me he strongly believes
the adoption of vertical/circular polarization did much more to ensure
the success of FM than conversion from mono to stereo, an opinion
shared by several other veteran FM broadcasters I know.

However, 40 years later, the Germans still aren't convinced!

Mark