I tried to read this article, but it had equal parts of truth and fiction. (The fictional parts were duly noted, but it is still confusing). It would be a lot more readable if you just stated what is now known to be true. The two ammeter photo is shocking. I never would have thought that was happening. I still don't understand the theory of where the current goes, but I can't argue with the photo. Come to think of it, in a Tesla coil, the current at the top is also not the same as the current at the bottom. The comments about loading coil Q not being critical are also surprising. I have always used top loading wires, so I guess I don't have to change anything based on this corrected information.
Rick N6RK On 4/23/2011 9:05 AM, [email protected] wrote: > On the subject of resonant loaded radiator - element please see my article at > > http://www.k3bu.us/loadingcoils.htm > > it took me some 40 years to realize wasaaap with loaded elements - current > distribution and efficiency. > We had a duel on the subject between K3BU, W9UCW, W5DXP in one corner and > W8JI and W7EL in another. W8JI still insists he is right. > Measurements and experience confirm "our" argument and as result of the > exchange, W7EL updated the EZNEC to allow real life coil with turns to be > modeled, similar to linear hair pin loading. > > It boils down to distribution of the current along the standing wave element > and efficiency is roughly proportional the area under the current curve. > Realizing that, it makes it plain to visualize the efficiency and performance > of the loaded antenna element. The trick is to make the high current portion > as long (area as large) as possible. 3/8 wave loaded elements, are the best - > large area and higher base impedance, close to 50 ohms. > > Linear loading is less efficient than coil, base loading worst, top loading > is the best, loading coil about 2/3 up is a good compromise especially for > mobile antennas. > > ON4UN had it right in earlier edition of his book, then W8JI convinced" him > to change to his "truth". Many found out with their own lying eyes what truly > works better. > > Happy Easter Egg to all! > > Yuri K3BU.us > www.MVmanor.com home of Glen Spey RadioFest > > >> <BR>> These days I use a 95 ft top loaded vertical and yes it "seems" >> to be "slightly" better then the 90 ft base loaded however >> this is just a feeling and I have no measurements to back it >> up with. But as long as my brain thinks it is better it is >> fine for me. >> >> Bottom line: I will never use linear loading again !! >> >> 73 Jim SM2EKM >> ----------------------------------------------------------------- >> On 2011-04-21 04:42, Lars Harlin wrote: >>> Hi Rag! >>> >>> Have you thought about the possibility to use linear loading? >> That could be >>> a good alternative when you cant put the loading on top... >>> >>> 73 de Lars, SM3BDZ >>> >>> >>> ----- Original Message ----- >>> From: "Stein Roar Brobakken" >>> To: >>> Sent: Wednesday, April 20, 2011 7:11 PM >>> Subject: Topband: 160m vertical with "top loading" >>> >>> >>>> Hi >>>> >>>> We are going to install a 18m spiderbeam @ LA9TJA for use for 160m >>>> >>>> We been studying different top loading configurations, but we >> can't have >>>> the >>>> wires stringed from the top because it will break the >> spiderbeam ;) >>>> >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK >> > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
