At 13:12 11/9/2009, you wrote: >Nick Hall-Patch wrote: > >>I don't really know the technical reasons >>for this, but it makes sense that a big antenna will deliver a more >>robust signal than a smaller one will. > >It's all about the aperture of the antenna. > >Even though the larger antenna has a less-tight F/B or forward lobe, the fact >that it is physically larger means that it is coupled into a greater area of >space. So it has a larger aperture. > >Because of this, i.e. it's coupling into a larger physical area, it can >average out the effects of ionospheric refraction of the signal, fading, etc. >over a larger area. This often is perceived as a better signal, or a steadier >signal. > >Hope that made sense.
Thanks for replying on this Rick. The explanation does ring a few bells (my antenna theory is pretty rusty, and I never considered it to be great). I guess I'm not surprised that a 450m Beverage antenna does a better job of sampling a wavefront than a phased small antenna system of 40m spacing, as one is a wavelength or more at MW frequencies, while the other is a smallish fraction a of a wavelength. But I'm a tad surprised that a 7m x 15m corner fed loop gives noticeably better reception than a 5m x10m Flag even if it's also a "splashier" signal, as both are a very small fraction of a wavelength. Perhaps your explanation gives way to mine (that when there is so little signal available for demodulation, that a small increase makes a significant improvement in the output signal's readability) with these small antennas, and that my comparison of the Grayland antennas and mine was not apt? Thanks again for getting the brain cells working a bit. best wishes, Nick ***************************** Nick Hall-Patch Victoria, BC Canada _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
