The problem isn't with shunt feed in particular. The increasingly
popular folded vertical on a grounded base tower is actually a form of
shunt feed.

A lot of people associate the term shunt feed with slant wire feed.
Slant wire feed is where the problem lies. While there are many of these
systems still operating due to grandfathering (KFBC in Cheyenne WY for
example) the FCC will generally not allow any new installations with
this feed arrangement because the slant wire itself introduces an
unwanted directional component into the radiation pattern. However, I
have heard that the FCC has allowed a few slant wire feeds for daytime
only stations under an STA.

Patrick Griffith, N=D8NNK, Westminster, CO

http://community.webtv.net/N0NNK/
http://community.webtv.net/AM-DXer/