How A WireGuard Is Tested
Appendix: ferrite test set-up
Testing uses a spectrum
analyzer and tracking generator with an impedance matching jig as shown in
the diagram below. This jig allowed different ferrites to be evaluated
with source and load impedances of 10 ohms or 150 ohms. Resistive matching
networks were used to convert from the standard 50 ohms of the spectrum
analyzer to the required impedance. The impedances were chosen as follows:
-
10 ohms represents the
lowest likely circuit impedance to be found in most applications, usually
within equipment, and shows up the ferrite to its best effect;
-
150 ohms represents the
common-mode impedance of cables (see for instance IEC1000-4-6 or
CISPR16-1) and shows the effect more likely to be achieved when putting
ferrite sleeves on external cables.
Tests are of a linear frequency scan from
MHz to GHz. The vertical scale is either 10dB per division or 2dB per
division. Across the trace is the 0dB reference level against which the
ferrite attenuation is measured. This level was normalized against a
straight-through connection to take out the frequency-dependent effects of
the jig. Although these are not themselves significant, the effect of a
straight-through length of wire has to be removed since it is against the
"attenuation" of this wire that the ferrite performance is judged. The
self-inductance of this wire is around 30nH which at, say 250MHz is 47
ohms; this puts in a significant amount of attenuation in a 10 ohm system
which must be normalized out.
How Our
Product Compares To Others
Below e-mail was sent in regards to our request
for independent testing of headset wire shielding.
<Message sent to John Coates>
>
>
I left a message for you on Friday, but I figured I would e-mail you as
well. I was doing some research on the Aegis part that you showed me. I
found the information you were looking for. First, your concern is
offering protection from phones that operate at frequency ranges such as a
2.4 GHz (for cordless phones) and 900 MHz-1.8 GHz (for cell phones).
Though these are the "operating" frequencies for these types of phones,
"radiated emissions" (radiation) occur at frequencies between 30MHz-1GHZ
which is well in the range of your ferrite. Next, I found out that Aegis'
part is made by one of my competitors. The model ferrite your using is a
direct cross reference to this part. In fact, your ferrite offers higher
impedance values (156 ohms compared to 105 ohms) than Aegis' part. (The
material is the EXACT same material. The difference is in the shape. as
you know your ferrite is longer. Ferrite performs better over length
rather than in bulk.) Anything they claim about their part, you can say as
well. Any test results they provide, your part will perform at least as
well and better. Also, I think aesthetically, it looks better. I also
found out that Aegis is trying to go big with promoting their part, so you
are on to something really good here. I think you could do well offering
an alternative for less than the $30.00 Aegis is asking!
Let me know what you think of all this.
<end e-mail>
RF SAFE NOTE:
When using a Shielded Headset,
radiation remains at your phone instead of partially being transferred
through the headset wire to your brain. For your safety, when the phone is
held near the body always use
radiation shielding between you and the cell phone
handset itself!
|
Headset Radiation Shields
are a two piece add-on accessory that can be installed in less than a
minute without tools. |
1) A
reusable radiation suppression clamp-on device similar to a clamshell and
named a WireGuard.
This device clamps over the headset wire above the plug
that
is inserted into the
phone. It incorporates a
ferrous composition based material which interacts
directly with the high frequency energy and suppresses it effectively
while allowing the voice signal to pass through to the earpiece unimpeded.
The housing is a white or black composite manufactured using nylon
resins. FITS ANY HEADSET!
 |
Sold on other sites for 29.99ea |
|
RF Safe has the WORLDS Best
Price! |
Just pay our Fixed Rate S&H of
$6.00ea - Delivered to your door!
6.00 WIREGUARD
2) Four (4) 5/8 O.D shields made
from silver coated
RF
Shielded Fabric. They are designed to eliminate the chances of stray
radiation from penetrating deep into your ear canal,
Earbud Shields
are simply inserted
under the earpiece's foam cover. They
fit all in-ear headset models with foam or gel bud covers.
 |
Sold on other sites for 17.99ea |
|
RF Safe has
the WORLDS Best Price! |
Just pay our Fixed Rate S&H of
$6.00ea - Delivered to your door!
6.00 EARBUD SHIELDS
Headset Hazards In The
News
RELATED ACCESSORIES FOR CELL
PHONE SAFETY
|
