Indeed! The purpose of the inverted V was for local NVIS coverage and was mentioned anecdotally to illustrate that folded back elements can be very effective if needed. They reduce the mechanical problems of erecting and turning a rotating dipole with minimal degradation. I can see a significant advantage where a shorter antenna is needed. We are fortunate to have a wide range of designs for our wide range of antenna problems.
Sent from my iPhone On Jun 18, 2012, at 10:27, Vic K2VCO <[email protected]> wrote: > I agree that folding the low-current parts of an antenna is a good way to > make it smaller. > > But there are several things at work in the comparison between the Steppir > element and the > V. Of course the height is one of them. But if you model an inverted V (90 > degree angle > between wires) and a dipole at the same height you will see that the dipole > has > significantly more gain. Many inverted V's are constructed with even smaller > angles, which > are worse. The V pattern also has smaller nulls on the ends. > > Finally, the Steppir undoubtedly has some kind of balun, and its feedline > runs > perpendicular to the antenna for 1/2 wavelength. All of these things improve > the nulls. > They also reduce noise pickup on the feedline. > > On 6/18/2012 5:26 AM, WILLIS COOKE wrote: >> A note on folded back antennae. I have a 3 element SteppIR with the 30/40 >> kit. The >> antenna is mounted at about 67 feet above the ground. I have compared the >> folded >> antenna at 67 feet to a full sized inverted V at 40 feet and find it >> noticeably >> stronger. Even though it is only a dipole which is a little more than half >> length it >> is noticeably bi-directive with deep nulls off the element ends. It is >> quite effective >> as a DX antenna and I believe the SteppIR claim that it is only one or two >> dB down from >> a full sized rotatable dipole. Of course, its improved performance over the >> inverted V >> is mostly because of the elevation difference, but I would not hesitate to >> fold the >> ends of a dipole if restricted by lot size or other physical restraints. >> >> Willis 'Cookie' Cooke K5EWJ& Trustee N5BPS, USS Cavalla, USS Stewart >> >> >> ----- Original Message ----- From: Don Wilhelm<[email protected]> To: Niel >> Skousen<[email protected]> Cc: Elecraft >> Reflector<[email protected]>; >> [email protected] Sent: Monday, June 18, 2012 6:18 AM Subject: Re: >> [Elecraft] >> Antenna Question >> >> Neil, >> >> When you see an antenna element folded back on itself like that, think >> "linear loading" >> (look it up in the ARRL Handbook or similar). There is no "magic", but it >> is one way >> of shortening an antenna. It is not as efficient as a full length antenna, >> but is more >> efficient than using loading coils. Everything is relative. If you have the >> space to >> put up full size half wave dipole antennas, that is the way to go. If you >> need >> shortened antennas for the lower bands, linear loading is one way to achieve >> resonance >> with shortened length. >> >> 73, Don W3FPR >> >> On 6/17/2012 11:26 PM, Niel Skousen wrote: >>> I'm pretty sure I've seen this antenna on the net, but don't recall the >>> name nor have >>> I been able to find a link to a description / design data. >>> >>> The county ERC has a 'shortened fan dipole' with three parallel elements, >>> spaced >>> about 18-24" apart on each side. the longest element folds back around the >>> mid-length element toward the shortest element. The antenna end insulator >>> / guy >>> rope is attached to the long element, where it folds back. There appears >>> (from the >>> ground) to be a 6~8" insulator / gap between the end of the shortest >>> element, and the >>> longest element where its been folded back. no traps, loading coils, or >>> loading >>> resistors that I can see. >>> >>> I'm assuming three or four band coverage (80, 40, 20, and 15 ??) with a 75m >>> dipole, a >>> 40m dipole (with 15m as a freebie), and a 20 m dipole. but would be >>> interested in >>> more technical details if anyone can decipher my text description above… >>> >>> Thanks Niel > > -- > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco/ > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
