excellent advice from one and all... thank you!
- R. Eric Sluder
W9WLW
resluder@yahoo.com
http://w9wlw.blogspot.com/
>________________________________
> From: Ken Brown <ken.d.brown@hawaiiantel.net>
>To: k9yc@arrl.net; Discussion of Ten-Tec Equipment <tentec@contesting.com>
>Sent: Thursday, November 7, 2013 11:51 PM
>Subject: Re: [TenTec] 160 M antenna
>
>
>
>>> What kind of bandwidth do you get with your inverted L, 50 kHz?
>>> Would I still be able to use a tuner in the shack if I want to bend
>>> it for more coverage on 160?
>>
>> Define bandwidth. Do you mean SWR bandwidth? Do you mean you can get
>> it to load?
>A very good question. And it brings up a couple of points that are worth
>mentioning.
>
>If your antenna has a wide SWR bandwidth, it may seem like it works
>really good, because it is so convenient. Operate the whole band without
>making any adjustments as you go from top to bottom of the band. Very
>convenient! Beware though that a wide low SWR bandwidth is often a sign
>of inefficiency. How wide is the 1.5:1 SWR bandwidth of a Heathkit
>Cantenna? Pretty wide. How much DX are you going to work with it? Not much.
>
>A quarter wavelength vertical over an excellent ground counterpoise
>system has an impedance of about 37 ohms. If you don't need a matching
>device to get a 1:1 SWR at the resonant point, then it is likely you
>have about 13 ohms of loss resistance (the kind that produces heat,
>versus radiation resistance, the kind that produces a radiated signal)
>that added to the 37 ohms of radiation resistance makes a perfect match
>to your 50 ohm coax. Very convenient. Not very effective. What would you
>rather have? A low SWR or a stronger signal? Many hams have chosen
>(perhaps unwittingly) a low SWR.
>
>A quarter wavelength that is folded over into an inverted L, instead of
>going straight up, has an even lower radiation resistance. You will (or
>at least you should) need a matching device to get the SWR down, unless
>you have a lot of loss. You are likely to have high ground losses,
>because your ground resistance is high and radial field is lacking. You
>could have a low SWR, and a wide bandwidth. It could be very convenient.
>Or you could reduce your ground losses and make your SWR worse. Not as
>convenient, but much more effective as an antenna.
>
>Yes there are antenna designs that have wide low SWR bandwidths, without
>being outdoor dummy loads. Discones, biconical dipoles, log periodics,
>etc. A fatter inverted vee "cage" will be an improvement, but you will
>still want to do whatever you can to reduce your ground losses.
>
>Have fun!
>
>DE N6KB
>
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