[TowerTalk] Lossy traps?

[Al Williams]

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" <w4tv at subich.com>
To: "'Al Williams'" <alwilliams at olywa.net>; "'Tower Talk'" 
<towertalk at contesting.com>
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: towertalk-bounces at contesting.com
>> [mailto:towertalk-bounces at contesting.com] On Behalf Of Al Williams
>> Sent: Wednesday, October 29, 2008 8:20 PM
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Lossy traps?
>>
>>
>>
>> ----- Original Message ----- 
>> From: "jimlux" <jimlux at earthlink.net>
>> To: "Dan Hearn" <n5ar at air-pipe.com>
>> Cc: "Tower Talk" <towertalk at contesting.com>; "Jerry K"
>> <w5kp at hughes.net>
>> 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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