>But what about at 100 mHz and 200 mHz?
** Ed-- What is the source of such energy? Using a cellphone would
seemingly provide more field strength at a more-dangerous-to-corneas
wavelength. Perhaps the amplifier builder should provide an shield-vest
to visitors in the shack like the kind dentists used to wear in days past?
>I worry that a) there is no
>filtering of harmonic energy through the windows (no pi network), and that
>the inverse square law is significant when the antenna is 100 feet away and
>an vacuum tube admirers corneas are inches away.
>
>I have never measured this, though many years ago I did perform part 15 EMI
>testing on communications equipment and discovered that small rectangular
>slots passed lots of RF energy.
>
>73s
>Ed N1TS
>'Festooned with fingerstock and nickel paint"
>----- Original Message -----
>From: "R.Measures" <r@somis.org>
>To: <TexasRF@aol.com>; <vk6apk@eon.net.au>; "AMPS" <Amps@contesting.com>
>Sent: Tuesday, March 02, 2004 3:24 PM
>Subject: Re: [Amps] 2 x 8877
>
>
>>
>>
>> >Whoa, wait a minute! That 150cm by 100 cm opening might be a waveguide
>> >beyond
>> >cutoff but the attenuation for this size opening is pretty low according
>to
>> >the Bill Orr Radio Handbook.
>>
>> ** My guess is that, at 28MHz, the radiation from the antenna is at
>> least 30db stronger than that from the window. .
>> >
>> >The chart for this size opening shows a constant attenuation from about
>> >1000mhz and lower frequencies on the order of 8db per inch. If the metal
>> >is .125
>> >inches thick then the attenuation is on the order of only one db!
>> >
>> >When the opening is reduced to .125 inches the attenuation is on the
>order
>> >of
>> >124 db per inch from about 2000mhz and down. With that level of
>> >attenuation a
>> >.125 inch thick screen would have about 30db of through loss.
>> >
>> >Cutoff means there is signal attenuation, not a total loss of
>transmission.
>> >
>> >73 de K5GW
>> >
>> _______________________________________________
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>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
>
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