If I am reading this response correctly, then any metal anywhere
decreases the radiated field from the driven element?!
I am not discussing directivity loss or gain--I am just curious
of whether the field in the vicinity of metal absorbs some of
the field and somehow that causes the total field of the driven
element to be reduced.
k7puc
----- Original Message -----
From: "Joe Subich, W4TV" <[email protected]>
To: "'Al Williams'" <[email protected]>; "'Tower Talk'"
<[email protected]>
Sent: Wednesday, October 29, 2008 10:07 PM
Subject: Re: [TowerTalk] Lossy traps?
>
>> Do the "other elements" actually absorb some of the power
>> creating an "IR???" loss of the source power?
>
> The current in the trapped, parasitic element creates an
> I^2R loss in the traps of that element. The decrease in
> current available for re-radiation represents an effective
> I^2R loss to the driven element because there is less total
> power available for radiation.
>
> ANY loss in the antenna system represents an overall decrease
> in efficiency. The effective gain of an antenna is equal to
> the directivity times the antenna efficiency.
>
> 73,
>
> ... Joe, W4TV
>
>
>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[email protected]] On Behalf Of Al Williams
>> Sent: Wednesday, October 29, 2008 8:20 PM
>> To: [email protected]
>> Subject: Re: [TowerTalk] Lossy traps?
>>
>>
>>
>> ----- Original Message -----
>> From: "jimlux" <[email protected]>
>> To: "Dan Hearn" <[email protected]>
>> Cc: "Tower Talk" <[email protected]>; "Jerry K"
>> <[email protected]>
>> Sent: Wednesday, October 29, 2008 3:55 PM
>> Subject: Re: [ comparable: both are essentially arrays of
>> coupled low Q
>> resonators.
>> >
>> The F12 style beam
>> > couples some nonzero amount of power into the other elements, so
>> > there's some IR loss there.
>> >
>> >
>> Do the "other elements" actually absorb some of the power
>> creating an "IR???" loss of the source power? Or do the
>> "other elements" become energized and then radiate
>> in possibly a detrimental change of the pattern?
>> k7puc
>>
>>
>> _______________________________________________
>>
>>
>>
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>> [email protected]
>> http://lists.contesting.com/mailman/listinfo/towertalk
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