wrote
There's a 99FM xmitter a couple miles to the SE of me, lower in elevation,
right in the path of all the
other stations - & right smack in the middle of the FM band. Pointing the
yagi in the exact opposite direction yields the best results for all other
stations.

I'm still looking for some vertical omni antenna designs. Sorry for any
duplicate posts, my hotmail account isn't very reliable.
____________

Using an omni v-pol antenna for the receiver with the problem won't help
much if the 99FM xmit antenna radiates v-pol as well as h-pol -- which is
typical for FM stations.

Really fixing the problem will require changing your receiver to one with
better selectivity. It is being de-sensitized by that local FM station.

An option would be to install a notch filter tuned for the local FM at the
input to the problem receiver. It will attenuate that local signal (and
others close to it in frequency, to some extent). A "5KFM" type notch
filter from Microwave Filter Company may do the job, for about $25 as I
recall. Here is a link: http://www.microwavefilter.com/

RF