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Re: [TowerTalk] book Tribander comparison test

To: "[TowerTalk]" <towertalk@contesting.com>
Subject: Re: [TowerTalk] book Tribander comparison test
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Thu, 24 Feb 2011 23:02:16 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
 > That being said, do you really think that given the same height and
 > feed line loss you could tell one or two db difference between
 > antennas.

Absolutely.  Over the long term one or two dB will be significant.

> I would still take the simplicity of a good LP. For that matter you
> could stack a pair of T-10's for the price of a single SteppIR, or
> even a TH-11, including the cost of a side gate - or spend your money
> on getting the T-10 higher.

That's an excellent *joke*.  Only a very small portion of the boom
length of a log-periodic is active on any one frequency typically
around 25%.  This leads to the log periodic having more than 3 dB
less gain that a well designed yagi of the same boom length.  Even
your stacked T-10s with their 30 foot booms will be more than 3 dB
behind the SteppIR 4 element yagi.  Stacking two T10s will not make
up the 3 dB deficit even if you can prevent the elements of the
lower antenna from fouling in the tower or guy wires.

Log periodic antennas - unless they have extremely long booms and
cover a restricted bandwidth - are grossly inferior to yagis (even
multi-monoband yagis like the Force 12 C31XR).

73,

    ... Joe, W4TV

On 2/24/2011 9:37 PM, Gene Fuller wrote:
> This thread is really running thin. That being said, do you really think
> that given the same height and feed line loss you could tell one or two db
> difference between antennas. At that point it's more a matter of operator
> skill!. I would still take the simplicity of a good LP. For that matter you
> could stack a pair of T-10's for the price of a single SteppIR, or even a
> TH-11, including the cost of a side gate - or spend your money on getting
> the T-10 higher.
> Gene / W2LU
>
> ----- Original Message -----
> From: "Mike"<noddy1211@sbcglobal.net>
> To:<towertalk@contesting.com>
> Sent: Thursday, February 24, 2011 8:52 PM
> Subject: Re: [TowerTalk] book Tribander comparison test
>
>
>> You are dead right it is a "tunable "monobander" and in a classification
>> of
>> its own really, so nothing to compare with.  Even on 20 meters a three
>> element Steppir has hardly has anything to compare with as most people
>> putting up a monobander for that band would choose a 4 t 6 element
>> antenna.
>> But it does work better than a 3 element tribander on 20 meters because it
>> tunes the whole band without traps, most short tri-banders are a
>> compromise
>> on 20 meters anyway.
>>
>> Mike
>>
>> -----Original Message-----
>>
>>> It would be, if they had motors to vary the distance between the
>>> elements
>>
>> Nonsense!  Some 30+ years ago W2PV showed that a monobander was a
>> monobander no matter what the element spacing as long as the elements
>> are properly tuned for their place in the array.  Gain is a product
>> of boom length as long as there are "enough" elements for the length.
>>
>> Tapered spacing only effects the bandwidth and feed impedance of the
>> antenna and with a SteppIR bandwidth has no meaning since the antenna
>> is constantly retuned for the operating frequency.
>>
>> SteppIR is a tunable "monobander" with a fixed length boom - other
>> than the optional fixed length elements for six meters, a SteppIR
>> has no traps or parasitic elements whose sole purpose is to allow
>> operation on more than one frequency at a time.
>>
>> 73,
>>
>>     ... Joe, W4TV
>>
>>
>> On 2/24/2011 6:57 PM, Dick NY1E wrote:
>>>    " As far as the SteppIR, it's a monobander for all  practical
>>> purposes."
>>>
>>> It would be, if they had motors to vary the distance between the
>> elements... otherwise its a tribander (ok 5 bander) with a good swr!
>>>
>>> Dick NY1E
>>> www.ny1e.com
>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>>
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