I remember very well when the FCC first adopted these rules. I did a
lot of homework at the time and, to my mind at least, it was junk
science. I don't blame the FCC (much) for adopting a standard, and for
most of us their exposure limits are not an issue. This unfortunately is
the exception.
73, Pete N4ZR
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blog at reversebeacon.blogspot.com.
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On 3/30/2014 12:19 PM, qrv@kd4e.com wrote:
I missed the low roof-mounted beam detail - that increases the
likelihood of indoors resonances!
Most low-level RF-exposure fear-mongering, other than at SHF/Microwave
frequencies, is likely junk science.
"Typical diagnostic sonographic scanners operate in the frequency range
of 2 to 18 megahertz, though frequencies up to 50–100 megahertz have
been used experimentally in a technique known as biomicroscopy in
special regions, such as the anterior chamber of the eye.[3] The choice
of frequency is a trade-off between spatial resolution of the image and
imaging depth: lower frequencies produce less resolution but image
deeper into the body. Higher frequency sound waves have a smaller
wavelength and thus are capable of reflecting or scattering from smaller
structures. Higher frequency sound waves also have a larger attenuation
coefficient and thus are more readily absorbed in tissue, limiting the
depth of penetration of the sound wave into the body (for details, see
Acoustic attenuation.)
"Sonography (ultrasonography) is widely used in medicine. It is possible
to perform both diagnosis and therapeutic procedures, using ultrasound
to guide interventional procedures (for instance biopsies or drainage of
fluid collections). Sonographers are medical professionals who perform
scans which are then typically interpreted by radiologists, physicians
who specialize in the application and interpretation of a wide variety
of medical imaging modalities, or by cardiologists in the case of
cardiac ultrasonography (echocardiography). Sonographers typically use a
hand-held probe (called a transducer) that is placed directly on and
moved over the patient. Increasingly, clinicians (physicians and other
healthcare professionals who provide direct patient care) are using
ultrasound in their office and hospital practices, for efficient,
low-cost, dynamic diagnostic imaging that facilitates treatment planning
while avoiding any ionising radiation exposure.
"Sonography is effective for imaging soft tissues of the body.
Superficial structures such as muscles, tendons, testes, breast, thyroid
and parathyroid glands, and the neonatal brain are imaged at a higher
frequency (7–18 MHz), which provides better axial and lateral
resolution. Deeper structures such as liver and kidney are imaged at a
lower frequency 1–6 MHz with lower axial and lateral resolution but
greater penetration."
Wikipedia
Can you share the results of the RF Exposure evaluation you are
required to perform by the FCC regulations affecting your license?
Your description of your antenna placement and your earlier comments
about QRO makes it sound like you have a much more serious problem
than "Thumper."
QRO to a low roof mounted tribander presents serious RF safety
issues every inhabitant of your home. FCC regulations that affect
your license require that you inform every inhabitant and guest in
your home about RF exposure safety of the risks they face.
Furthermore, every inhabitant and guest must agree to accept their RF
exposure risks.
http://www.arrl.org/fcc-rf-exposure-regulations-the-station-evaluation
73 Frank W3LPL
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