Somewhere in my archives, I have an article from
the old Broadcast Management and Engineering magazine, an article
written by a known broadcast consulting engineer
on this subject. As he was located near me when I lived in Northern NJ,
I met with him and was able to acquire some of
his notes and documentation. Hopefully I still have both. He measured the
seasonal changes through the year to the signals
of various local and semilocal transmitters and from that concluded that
tree leaves did provide measurable degradation in signals at AM frequencies.
If I can't locate my copies, I may be able to locate the article on the web.
I'll be able to provide more info later for anyone who might be interested.
Russ Edmunds
15 mi NNW of Philadelphia
Grid FN20id
<wb2bjh@xxxxxxxxx>
AM: Modified Sony ICF 2010's barefoot
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
Onkyo T-450RDS; Tecsun PL-310 ( 2);
modified Sony ICF2010 w/APS9B @ 15';
Grundig G8 w/whip; modified Sony ICF2010 w/whip
________________________________
From: Nick Hall-Patch <nhp@xxxxxxxx>
To: Mailing list for the International Radio
Club of America <irca@xxxxxxxxxxxxxxxx>
Sent: Monday, August 5, 2013 1:19 PM
Subject: [IRCA] Fwd: Topband: tree losses
From a discussion on the Topband list concerning
the effect of trees and foliage on a transmitted
signal. Make of it what you will.
best wishes,
Nick
>From: "Richard Fry" <rfry@xxxxxxxxx>
>To: <topband@xxxxxxxxxxxxxx>
>Date: Mon, 5 Aug 2013 06:05:13 -0500
>X-Mailer: Microsoft Windows Mail 6.0.6002.18197
>
>Rudy Severns wrote:
>>Tom's correct, the issue is not "resonance" but
>>rather what, if anything, happens when you have
>>a so-so conductor/insulator (a tree) in the
>>near-field and/or further out. Do the losses matter?
>________________
>
>Here are several data points on this subject.
>
>Recording the relative readings on the dBµ and
>S/N displays of a Tecsun PL-310 tuned to a 790
>kHz directional station about 52 miles east of
>me, radiating about 1 kW in my direction:
>
> Location
> dBµ S/N (dB)
> (Tecsun 4-1/2 ft AGL)
>Area clear for 50 ft around 32 15
>Pin oak tree, 3' diameter trunk, 42 24
> east side against trunk
>Ditto, but west side of trunk 34 14
>Gnd Wire of 50' utility pole 48 24
> (Tecsun 9 ft AGL)
>Gnd Wire of 50' utility pole 50 24
>
>The field improvement when the rx is held
>against the east side of the trunk is completely
>gone when the receiver is moved to the east
>about 15 feet. So the effects are quite localized.
>
>These locations were all within 100' of each other.
>_________________
>Topband Reflector
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