Correction :
For the centerfed vertical, it should not be more than 1.25 wavelength at
the highest frequency. i.e. like a vertical extended double zepp. - 5/8's
wave each side of center.
Gene
----- Original Message -----
From: "Gene Fuller" <w2lu@rochester.rr.com>
To: "Mark Beckwith" <n5ot@n5ot.com>; <towertalk@contesting.com>
Sent: Monday, November 14, 2011 12:17 PM
Subject: Re: [TowerTalk] verticlas used on multiple bands fed with a tuner
> Hi Mark -
>
> A GOOD vertical antenna is perhaps the easiest way to get the low
> radiation
> angle you would like for DX'ing. Some of the things you need to keep in
> mid to get a "good" base fed system include -
> 1. The vertical should be long enough to have a relatively high radiation
> resistance when compared to the groun/radial system
> 2. The length of the radiating portion of the vertical should not be more
> than about 5/8's wave. You will start to get lobe splitting once you get
> above a half wave and that will show up as, at first little, but growing
> as
> the lenght increases, low angle "rabbit ears". At the same time the "main
> lobe will be shrinking and risng and the desireable low angle radiation
> will
> be decreasing.
> 3 You'll want an efficient tuner/matching network.
>
> Another approach, if you are "radial system challenged" is to use a
> centered fed vertical fed with something like 450 ohm feedline and a
> "balanced" tuner. This generally requires a higher support structure, but
> for the large part avoids the need for a radial system. I've found that
> 40-
> 45 feet (not critical) fed with 450 ohm line and a balanced tuner can be
> quite effective for 10-20 and still quite useable on 40. General rule of
> thumb: not more that 5/8's wave at the highest frequency, and/or at least
> .4
> wavelength at the lowest frequency (half that figure for a ground fed
> vertical).
> Good luck with however you go.
>
> Gene / W2LU
>
>
> ----- Original Message -----
> From: "Mark Beckwith" <n5ot@n5ot.com>
> To: <towertalk@contesting.com>
> Sent: Monday, November 14, 2011 10:00 AM
> Subject: [TowerTalk] verticlas used on multiple bands fed with a tuner
>
>
>> Re: vertical antennas you can use on multiple bands with a tuner, are
>> there magic lengths? I would just as soon put up one for "the low bands"
>> and one for "the high bands." Or whatever. I figure the answer has
>> already been determined long ago and I don't feel a particular need to
>> discover it myself is someone can just tell me what the prevailing wisdom
>> is.
>>
>> Thanks in advance,
>>
>> 73 - Mark, N5OT
>>
>>
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|