900 mhz radios would probably work but they will set you back a grand.
I maintain and install 802.11b cisco 350's for my employer.
What kind of radios and antennas are you running now?
Sometimes a bit more gain can help with tree interference. It's not the
"right" way but when you are trying to save bucks and only need about a meg
of bandwidth, it will work.
I just finished installing a 40 foot tower at my residence and will be
shooting 2.5 miles to a 400 foot microwave tower that has a ds3 passing
through via nec digital microwave bridged together by a cisco router. I will
be coming out of the router using a cisco 340's shooting to my house via a
24 db gain antenna mounted at 200 feet using lmr 600 coax. I will also have
the same antenna at my house mounted on 40 foot of rohn 25g. I know that I
have a fresnel zone issue about a mile from my house but if I can get over a
meg of bandwith I will be happy. I will be turning off my dsl connection and
my dial tone as I will use vonage for phone service. If it becomes a serious
issue for me I will stack enough tower to resolve the tree issue but I will
have to guy the tower which I really don't want to deal with.
I have imstalled links varying from 100 yards to 20 miles and trees have
givin me fits in the past but usually there is a serious rsl issue also.
But the quality of radios can make a big difference when you are dealing
with a "borderline" issue.


"Gordon Montgomery" <gordon@lsi.com> wrote in message
news:11er99421bpd291@corp.supernews.com...
> I'm looking for alternatives to 802.11b. I have a 4 mile
> stretch that is giving me fits. I have clear line of site
> except that a rather large tree sqeezing in on the
> fresnel zone about dead center. Does anyone
> have any recomendations on Laser/Optical/Etc.
> devices? I can't relocate either antenna more than
> about 10 feet side-to-side. I feel like a midnight
> chain-saw visit is in order.
>
> Oh, and BTW... it has to be inexpensive. ( < $750 ).
>
> Thanks,
>
>
> Gordon Montgomery
> Living Scriptures, Inc
> gordon@lsi.com (anti spam - replace lsi with livingscriptures)
> (801) 627-2000