Yup ... I was wrong again, but the trouble is I can't figure out why. I mean, it's easy to verify the cloverleaf pattern with EZNEC and I have done so, but I know that I have modeled something similar with an off-center feed in the past and gotten an end-fire pattern. As soon as I figure out what that was I'll come back here and try to clear up the confusion I have caused, but in the meantime let's all just agree that I don't know what I'm talking about.
sigh ... 73, Dave AB7E On 8/25/2011 11:13 AM, Guy Olinger K2AV wrote: > Sorry to interject, but a fullwave fed at the 25% point has a clover > leaf pattern. It only has the two halfwaves in phase colinear > behavior when fed very near the center. Even fed at 45% it has a > significant cloverleaf lobe and a NULL in the center Easy to verify > with any modeling program. 73, Guy. > > On Wed, Aug 24, 2011 at 8:37 PM, David Gilbert > <xda...@cis-broadband.com <mailto:xda...@cis-broadband.com>> wrote: > > > Yes, Don ... you are totally correct. For some reason I was thinking > about a full wave antenna fed at the 25% point (I have built such > antennas before), which looks like two colinear half waves fed out of > phase. The current phasing along the antenna would indeed be much > different and give a cloverleaf pattern if it were end fed. I > wholeheartedly apologize for any confusion I may have created. > > 73 and thanks for catching my mistake. > > Dave AB7E > > > On 8/24/2011 3:23 PM, Don Wilhelm wrote: > > Actually Dave, a full wavelength wire will have a " 4 leaf clover" > > pattern - that is neither broadside to the antenna, nor off the > ends. > > Check out the pattern for a 1 wavelength long wire in the ARRL > Antenna > > Book. The maximum radiation is about 28 degrees from the wire - the > > radiation from the end is almost zero. > > > > The elevation angle of maximum radiation is similar to a half wave > > dipole - about 15 degrees with a lesser lobe at 45 degrees (that is > > for a wire 70 feet high, at lower heights, the angle will be > greater). > > > > 73, > > Don W3FPR > > > > On 8/24/2011 5:34 PM, David Gilbert wrote: > >> > >> I'm not sure I see the advantage. A full wave end fed antenna > would > >> theoretically have the same very high feedpoint impedance, and > would > >> additionally blow most of it's radiated energy at a fairly high > angle > >> off the ends of the antenna instead of broadside at a lower > angle. If > >> you find it that easy to tune, I suspect that electrically it > really > >> isn't that close to a full wavelength ... possibly because of > coupling > >> to earth (if it is low) or nearby structures. Either that or > there is a > >> lot of loss in the system somewhere. > >> > >> 73, > >> Dave AB7E > >> > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > <mailto:Elecraft@mailman.qth.net> > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
