The front of your microwave oven has a metal screen. The size of the
holes dictates at what frequency energy will be contained to prevent
unwanted "cooking" of ambient (moisture-based) objects such as your face
while you watch your pizza pops being prepared for consumption.
Basically, the high (gigaHertz) frequency energy is unable to travel
through, as the viewing holes are physically smaller than the actual
wavelength. The same principle can be applied to dissipative (energy
absorbing) materials such as carbon as it relates to the various weaves
and their ability to reduce or block the carrier frequency.
Given that all layups are hand-made the overlap, weave skewing, type and
density of CF and orientation makes even two fuses from the same
manufacturer significantly different EMI/RFI-wise...
"Kurt W. Zimmerman" wrote:
>
> One of the items you've failed to mention is the fact that the carbon
> EMI/RFI insulator factor is also based upon frequency. From my observation
> higher frequencies are less effected by carbon than lower. I've noticed
> this with my new Organic 2m using 50 MHz. However most of the reports that
> I've received from other Organic owners using 72 MHz don't seem to be
> effected as much. Our European fellows using 35 MHz have reported more
> problems with the carbon EMI/RFI insulating factor.
>
> As I reported some time ago on this reflector I've also noticed that
> orientation of the plane may have an effect to RX reception. Nulls are
> produced typically at the ends of the antenna whereby causing a weaker
> signal to the RX.
>
> Just more food for thought.
> Kurt - W2MW
>
> -----Original Message-----
> From: Simon Van Leeuwen [SMTP:[EMAIL PROTECTED]
> Sent: Saturday, July 05, 2003 9:40 PM
> To: 5-Soaring Forum
> Subject: [RCSE] RF Tidbits
>
> To help right some bad information being spread about, here are a few
> thoughts:
>
> First off, NiCD and NiMH have similar discharge curves. This makes
> devices such as what Sheldon from YNT and others offer perfectly
> acceptable at discerning pack voltage for either technology. Simply put,
> there is NO DIFFERENCE between how these devices can or can not be used
> with these two technologies.
>
> In combination with some time measurements, the process of understanding
> just how much power is still available to fly safely has not changed.
> This form of measurement will remain the most expedient way of measuring
> pack integrity for the foreseeable future.
>
> The idea of a "gas gauge" is not new. The many variables (different
> rates of consumption, cell/pack degradation, etc.) that need to be taken
> into account in order to accurately display when a particular pack would
> be considered "empty" over it's serviceable lifetime are too numerous to
> make a portable unit viable. The best one could hope for is already
> available, and still requires the user to periodically test capacity in
> order to observe trends. The (raw) diagnostic (past-tense) data you
> gather is only as good as your ability to understand it. No gas gauge is
> going to tell when it is unsafe to attempt another flight, the user
> still has to make that decision. In other words, you still have to
> determine the amount of energy consummed per flight to understand
> whether you have enough reserve to go again. This is no different than
> utilizing an ESV or an LED array. I applaud those who continue to move
> towards helping us better understand the life-blood of our hobby/sport.
> The C-volt (any ESV), LED-based arrays, and W/Hr meters are just such
> products.
>
> Regarding single conversion (sC) versus dual conversion (dC) RX's, and
> which is superior:
>
> In an outright lab comparison, of the 3 OEM sC's I have tested, the sC
> units S/N ratio were consistently inferior to dC either of the same make
> or otherwise. This does not make up a sufficiently large test base to
> make an all-encompasing statement, but it is enough to make a point.
> When I attempted to discuss sensitivity/selectivity with the OEM, I was
> rebuffed.
>
> In the real world, if it works for you...great. I find it amusing that
> people need to defend one particular "this" over "that", as neither gets
> to the heart of the issue, which is whether there is adequate RF
> headroom to allow unimpeded communication between your particular TX and
> RX. Your "particular" installation technique will have a greater impact
> on RX efficiency than any other factor.
> Here are some points to ponder:
> - CF being dissipative by nature is an excellent EMI/RFI insulator,
> using it as an antenna is silly
> - installing the antenna lead in carbon booms will have an adverse
> affect on sensitivity, therefore decreasing useable range. If you
> wish to discover just how much, do a (rigorous) range test and
> determine this for yourself. If you are interested in ensuring as much
> RF headroom as possible, then install the antenna externally.
> - any RX, sC or dC will work within the confines of a carbon boom,
> however the losses will vary on every single installation. Therefore
> any all-encompassing statements about any particular RX brand working
> better (or worse) are misleading.
> - shortening (or lengthening) the RX antenna will affect range.
> Again, depending on that A/C's unique installation, it may even
> enhance usable range. It is more likely to reduce range
> though.
>
> Finally, heli pilots have long known NOT to utilize sC RX's, and have
> proven to themselves over and over that dC RX's offer greater usable
> range. How you choose to interprete this nugget is your choice.
>
> *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
> Simon Van Leeuwen, Calgary, Alberta
> RADIUS SYSTEMS
> Cogito-Ergo-Zoom
> IAC25233*MAAC12835*IMAC1756*LSF5953*IMAA20209
> *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
> RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
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--
*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Simon Van Leeuwen, Calgary, Alberta
RADIUS SYSTEMS
Cogito-Ergo-Zoom
IAC25233*MAAC12835*IMAC1756*LSF5953*IMAA20209
*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and
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