Topband: 160m vertical with "top loading"
k3bu at optimum.net
k3bu at optimum.net
Sat Apr 23 09:05:24 PDT 2011
On the subject of resonant loaded radiator - element please see my article at
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!
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
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