[Towertalk] Attenuation of trees

[Jim Ussailis]

Tree attenuation at 7 MHz? I shouldn't think so. N1CQ and I have agreeded 
to disagree on attenuation at HF. My opinion is that I see much more 
multipath than attenuation at 700 MHz and 2400 MHz, so that the 
attenuation at HF must be small, as foilage attenuation increases with 
frequency.

As I recall, the attenuation at 50 MHz was only a couple dB in a 
rainforest. I also recall 4 dB into a wood frame house at 850 MHz.

Someday I'll measure it.

A comment on vertcals.

Try a full quaterwave on 40, with as many radials as you can deal with. 
Don't believe the quarterwave radial stuff. Make them as long as you can. 
I often use this antenna for things like field day. It gets out very well.

Normally I have about 33 ft of aluminum tower sections, or about 35 ft of 
2" irrigation tubing. For the tower I've used a plastic milk carton for 
an insulator, For the tubing I have used a glass soda bottle(we get them 
here). I've also used a plastic "closet flange" turned upside down (that is 
the thing that attaches a toilet to the sewer pipe).

For radials, I came across two 4K ft reels of #14 appliance wire a few 
years ago. I leave the insulation on. My radial lengths vary between 40 
ft and 100 ft. Generally I use 30 to 40, but have used more.

Have fun!!

JIm, W1EQO



On Mon, 20 May 2002, Jim White wrote:

> will be putting up a vertical antenna for receiving this weekend....on 40
> and 80 meters - one location is thick with pine trees taller than the
> vertical - should I even think about problems at this low a frequency?
> 
> K4OJ
> 
> ----- Original Message -----
> From: "Jim Ussailis" <ussailis@equinox.shaysnet.com>
> To: <towertalk@contesting.com>
> Sent: Sunday, May 19, 2002 11:30 AM
> Subject: [Towertalk] Attenuation of trees at 50 MHz
> 
> 
> > There was a study done several years back (perhaps in 1989 or 1990) on
> > attenuation of trees in India at 50 MHz.
> >
> > Since I only get Radio Science, IEEE Trans on Antennat & prop, and IEEE
> > Trans on MTT, it would be in one of those.
> >
> > I would look in Ant & Prop first.
> >
> >
> > Jim, W1EQO
> > _______________________________________________
> > Towertalk mailing list
> > Towertalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> 
>