Subject:  (Ozaktas) The new RF/MW meter... (fwd)
Date:     Mon, 21 Sep 1998 132200 -0500 (CDT)
From:     "Roy L. Beavers" <rbeavers@llion.org>
To:       emfguru@hotmail.com
--------------------------------------------------



---------- Forwarded message ----------
Date: Mon, 21 Sep 1998 19:31:51 +0400 (EET DST)
From: Haldun Ozaktas 
To: rbeavers@llion.org
Cc: haldun ozaktas ,
    haldun ozaktas 
Subject: The new RF/MW meter...


Subject: The new RF/MW meter...

The new Micro Alert Alarm looks very interesting since it seems
to be the first consumer device in the market to really measure
down to microW/cm^2. (http://www.maui.net/~emf/MicroAlert.html)

The information provided on the web page is not totally clear,
but if the device is reliable and can indeed sense as low
as 1/3 microW/cm^2, it would be indeed very useful.
I look forward to receiving information from anyone who
has anything further to say about this device, as well as any
other similar device.

Such a device can go a long way towards crudely determining 
field levels. The device is not a meter, but if it is indeed
able to clearly ascertain (can it??) whether the field is 
less than 1/3, 1, 3, 10 microW/cm^2, even these four levels
would be sufficient for general purposes. (I think most of us agree
fields higher than 10 are most likely really dangerous. As for
fields lower than 1/3, the danger may be less or even non-existent.
Even if there is a danger below 1/3, it would be relatively hard
to avoid such low fields in modern communities.)

Most desirable would be a flat frequency response. Since
this is not easy for a cheap meter to have, it is necessary to 
know its frequency response/sensitivity curve. If such a curve
is available, the meter can be very useful since in most
practical instances, we actually may know the frequency:
an FM/TV broadcast, a cellular tower, etc. By pointing the
device in different directions and trying to shield it from
all but one source at a time, such a curve would also enable
one to untangle multiple sources to a certain extent.

Let me conclude by defining what I believe is the ideal meter
for public protection, standard equipment needed by everyone:
Please comment and improve. Let us define what is needed for 
those who wish to produce them.

-Sensitivity down to 0.1 microW/cm^2, less is not enough.
 It need not read specific values beyond 100 microW/cm^2,
 but just indicate that the intensity is more than this. 
 (There are other meters for this higher range.)
-Meter readout with 10-20% accuracy, more is not needed.
-Frequency response should cover 10-100 MHz to 5 GHz.
 This covers FM, TV, cellular, and some radar. Ideally
 it should be flat in this region within 20% accuracy. If not,
 a clear reliable response curve should be provided.
-Price less than few hundred dollars

Possible enhancements at increased cost:
-It would be desirable to cover frequencies from several
 hundred kHz up to 10 GHz. In this case, it would be best
 for the meter to have switchable frequency ranges. These
 ranges should be chosen so as to contain exclusively a few
 most common sources each. For instance, 500 MHz-1.5 GHz
 range can cover cellular, the 10-500 MHz range can cover
 FM and TV, the 1.5-5 GHz range can cover. . . These ranges
 should be approximately flat in themselves and cross over
 at their -3dB points or so. This would give us the means
 to be able to crudely analyze the spectrum in terms of the
 most commonly encountered sources, making it easier to 
 isolate multiple sources.

It would also be nice to have a continuously tunable meter,
but that would almost surely be too expensive. With careful
observation of the environment and directional measurements,
one can go a long way with such simple meters to ensure that
one is living in as low an intensity level as possible.

Haldun

________________________________________________________________________
Haldun M. Ozaktas
Bilkent University                      (90) (312) 290 1619
Department of Electrical Engineering    (90) (312) 266 43 07 (secretary)
TR-06533 Bilkent, Ankara, Turkey        (90) (312) 266 41 26 (fax)
www.ee.bilkent.edu.tr/~haldun           haldun@ee.bilkent.edu.tr



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Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html