Actually, it's the other way around. The isotropic radiator is what's theoretical. The TIA-329-C standard provides instructions for creating a real-world reference dipole radiator, upon which real-world measurements can be based..
There are many antenna experts who disagree with some of Cebik's allegations. The isotropic radiator makes sense at frequencies above 1 GHz, and that is why the contemporary antenna experts settled on that as a break point. It seems pointless to debate this issue, since a standard has been published which reflects a worldwide consensus. Let's move on. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Saturday, May 10, 2008 5:05 PM To: [email protected] Subject: Re: [Repeater-Builder] Antenna Gain (WAS antenna question - Dip It and Scotch Kote) At 5/10/2008 10:16, you wrote: >Which begs the question: Why are antenna manufacturers and vendors still >using dBi to express gain for antennas operating at VHF? The term dBi >represents gain of an isotropic (point-source) radiator such as an antenna >with a parabolic reflector; it is inappropriate to use dBi for a dipole >radiator. I think we all know the answer- it "sounds better!" Actually, dBi makes more sense from a theoretical (designer's) standpoint. The late antenna expert L. B. Cebik W4RNL once published an article explaining why he preferred dBi over dBd. I can't find a link to it now, but the gist of the article was that the ideal dipole "standard" is almost as theoretical as the isotropic source, & that it is possible to closely approximate the isotropic radiator, so the "real world" dipole reference is in fact a fallacy. Bob NO6B
