[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [IRCA] West Coast TPs Sept 19
- Subject: Re: [IRCA] West Coast TPs Sept 19
- From: Scott Fybush <scott@xxxxxxxxxx>
- Date: Wed, 19 Sep 2018 23:21:56 -0400
- Content-language: en-US
- Delivered-to: archive@xxxxxxxxxxxxxxxxxxxx
- Delivered-to: irca@xxxxxxxxxxxxxxxx
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fybush-com.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=LgqDwVav3vDamllOd5xLKqOYsJbbEiHtiBkQtpkDB84=; b=u/jWPG/ZlLmef0AL0ObwZ+hbHRHHp6LzGxmWMwdqRU/JajngEIfl+00bV2JR+kqx+/ GD+5qq77E3zWEbzAi6GOAtJ+t56oTlkuR+mrDj2r7ryQlxAMGhK9EYdR+m2IHu3yHm9p vorQYQJFB59k+ujiqVZ9RG+ijyNWzgc4/5sP7vQheE/CsdqL+GjDdVJhG28iBg4KqAj0 QQECLeLTWS7jAGyA9+sJxxERx871PLQTXu9t3BERl+xqqDvTVBs1705qO57tm8Iqx2Ti 9tgHtgiwpShv1rNZnYziI1zPCPtvUn7uXkJj29qiPEo/PAX6uhJUAP34Cp6oniBVodTK DyCQ==
On 9/19/2018 4:26 PM, Chris Kadlec wrote:
Henan often interfered with it at night and Iâd often hear 972 Pyongyang from atop the >skyscrapers downtown (like with many stations, I could only hear them atop the towers >*shrugs* - even though people say things like height make no difference with AM, >something must explain that; perhaps steel conducts signals).
I don't think you're crazy here.
Here's what I think might have been happening: if you're in a crowded
downtown of a big city like Seoul, at ground level you're probably in a
somewhat effective Faraday cage. A 300-meter-wavelength signal is going
to have a hard time penetrating a downtown street grid where the
buildings are only 20 or 30 meters apart from each other and hundreds of
meters tall.
Get on top of those buildings and you're out of the Faraday cage. The
signals are still being conducted along ground (and perhaps up the steel
of the buildings to your radio) rather than through skywave - but up on
the roof you're not within the giant steel city grid that attenuates the
long wavelengths of MW radio.
And we've known for 90+ years that steel building frames can have
effects on MW signals - go all the way back to 1922, when AT&T started
its station WBAY at one of its buildings in Lower Manhattan, only to
discover the building frame itself was resonant at WBAY's 360 meter
wavelength, causing it to absorb much of the transmitted signal. They
had another station, WEAF, at a different location that worked better
and they moved their programming over there.
(We had a similar situation in 1922 here in Rochester - the Times-Union
newspaper put WHQ radio on the air in March and found its building
absorbed too much of the signal from the rooftop antenna, so they shut
it down and sold the license to George Eastman of Kodak fame, who
restarted it later that same year as WHAM.)
s
_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca
Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers
For more information: http://www.ircaonline.org
To Post a message: irca@xxxxxxxxxxxxxxxx