"I'd give it greater than 50/50 that the entire thing is a total sham" I think this 'device', the so-called hidden antenna is particularly effect beings the advert shows it installed on the back of the phone with the battery removed - install the battery and it truly *is* a 'hidden antenna'. What does the mass of that batt pack do when it is installed over the 'hidden antenna' - and what effect does that have on the performance promises of the 'hidden antenna'? What the average person (and average piclister as well) does not realize is that *real* performance could be had by going with an 'elevated' feed style antenna - something with some well-known radiation characteristics even compared with the usual end-fed half-wave or the helically shortened 'stubby' style that is now so prevelant. ... and all for the cost of around what these 'hucksters' are asking for a piece of sticky-backed aluminum tape - the same kind of aluminum tape *we* used to use to wrap RF connections for the purpose of improving 'shielding' ... VHF/UHF Handheld 2-way Transceiver Performance - a primer The poorest performance is seen in hand-held gear at 50 MHz/6 Meters (and below) where a quarter wavelength \ is 4 feet 11 inches. On this band it's best to grasp the talkie tightly (becoming part of the 'ground' or conterpoise system) - and preferably using a telescopic whip as opposed to the supplied 12" helically wound 'rubber duck' style antenna. Operation from within a vehicle is almost impossible due to the 'waveguide beyond cutoff effect' due to the structure of the vehicle. Experiments with an Azden AZ-61 over a number of years and with several low-band VHF repeaters are the basis for this evaluation. At 146 MHz/2 Meters things improve. A quarter-wavelength is now only about 19 inches - tightly grasping the HT's body *still* improves the signal into the repeater when marginal into "the machine" (the repeater). A telescopic whip, about 19" at this frequency, will still outperform a a 6 or 8" rubber duck antenna. Operation from within a vehicle shows definite signs of signal attenuation (waveguide beyond cutoff effect still in play). At 440 MHz/ 70 centimeters - the situation is such that the radio supplies most of it's own ground/counterpoise. A quarter-wave antenna is now only 6". No need to 'squeeze' the HT and tightly couple ones body into the antenna system. At this freq regarding operation within a vehicle - the 'waveguide beyond cutoff effect' is about nil ... At 850 MHz cellular - same conditions for 440 MHz apply. Antenna lengths are about 3" for a quarter wave - and can easily be shortened (made stubby) by 'helical winding' the active element ... body of 'radio' supplies ground plane/counterpoise. Operation within from vehicle very favorable. 1296 MHz/23 cm upward - all that applies to 440 MHz and above applies. The 'Rayleigh fading' is now most pronounced, however - move back and forth a foot and hear many 'fades' on a weak signal ... Jim ----- Original Message ----- From: "Mike Kendall" To: Sent: Wednesday, August 29, 2001 2:27 PM Subject: Re: [OT] Internal Antenna baloney! > Hi Sean, > Yes I agree and I bet it is capacitively coupled if it does in fact work. > A magnetic base of a mobile whip has no problems capacitively coupling into > the metal car through the paint. Nobody would know for sure without > actually testing this out but a solid copper foil may ground out even better > than the stupid looking antenna element. I'd give it greater than 50/50 > that the entire thing is a total sham that could not be properly documented > in any way. Why don't they publish the data proving them right?? I've seen > antenna scams before. There was a guy who claimed to have patents and was > selling his junk to the military (or at least trying) He had people pluging > in his small piece of junk into everything from satellite backpack radios to > medium power vehicle VHF radios. NOSC in Point Loma even measured the > antenna in a hyperbolic chamber and exposed him scientifically. All that > didn't slow down the herd of uneducated believers that refused to listen to > sound advise. I would classify the stick-on antenna as a "placebo cellular > phone antenna". It works in the minds of the people who need to justify > their purchase and feel better....or maybe it does work better? Personally, > I would never modify my cell phone in the first place. I've seen people > clip portable yagis into the windows of their car and talk from San Clemente > island back to the mainland on cells over 50miles. > Mike > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu