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Re: [TowerTalk] New antenna system

To: "Joe Subich, K4IK" <>,"'TowerTalk'" <>
Subject: Re: [TowerTalk] New antenna system
From: "4x1ad" <>
Reply-to: 4x1ad <>
Date: Mon, 8 Nov 2004 23:34:37 +0200
List-post: <>
I can agree with most of your remarks excepting one : "the boom length has
been compromised slightly". I don't think that "slightly" is the right word
in this case.
73 & mni DX

----- Original Message ----- 
From: "Joe Subich, K4IK" <>
To: "'4x1ad'" <>; "'TowerTalk'" <>
Sent: Monday, November 08, 2004 11:11 PM
Subject: RE: [TowerTalk] New antenna system

> Morel,
> > But what about F/B or F/S ratio?  Aren't they of any importance?
> Of course they are.  If you spend a little time working with the
> modeling programs (or reading the ARRL Antenna Book), you will find
> peak F/R is relatively narrow on most yagi designs and most fixed
> tuned antennas fail to achieve real pattern performance over even
> half of a given band.  Often the F/R of an antenna set up for CW
> will fall to less than 10 dB on phone.  For example, a three element,
> 16 foot boom 20 meter yagi might show F/R > 20 dB below 14.100 but
> at 14.200 it's down to 11 dB and only 7 dB at 14.300.  Similarly,
> SWR is greater than 2:1 shortly above 14.100.
> > Personally, I can't take too seriously the manufacturer claim
> > that "a long boom is not needed to achieve near optimum gain
> > and front to back ratios on 20 - 10 meters since the SteppIR
> > can control the element lengths" !!!!
> The adjustable element lengths allow the SteppIR antennas to achieve
> a very nice balance between the gain available for a given boom
> length, F/R and SWR.  Quite simply, modeling will show that, within
> limits Gain and F/R are nearly constant flat as one changes the element
> spacing (e.g., the position of the driven element in a three element
> yagi with a fixed boomlength) as long as the element tuning is
> adjusted to compensate.
> With the SteppIR antennas, the boom length has been compromised
> slightly in favor of higher gain on the low end of the range to
> the detriment of best possible F/R on 10 meters.  That is a trade
> that many are willing to make.
> 73,
>    ... Joe, K4IK


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