[Antennas] VSWR on Log Periodic.

2002年4月28日 20:02:17 -0400

Comment inserted below:
Cletus W Whitaker wrote:
>> de WB2CPN South Central Pennsylvania USA 2002年04月27日
>> Everything I know I learned from some one, so this is no exception. Which
> means I'm never afraid to ask, no matter how dumb:
>> If I take my trusty Bird ThruLine Wattmeter and measure the indicated power
> going into the transmission line, and the power coming back, then measure
> the loss of the transmission line, why does that not tell me the level of
> power arriving at the antenna and the level of power reflected by the antenna.
> The usual SWR formula for P1/P2 should tell me the SWR at the antenna. Or does
> it? If not, why not? My early observations indicate that the SWR at the far
> end of a shorted transmission line is Zero.

Please tell me HOW The SWR can EVER be Zero?
Don N8DE
> (My General Theory of Antenna
> Activity states that the Current at the ends of a long wire or dipole antenna
> is immeasureablly close to Zero.) The truth is mixed in here someplace.
> As some one said, the actual SWR of the antenna (the load) is always greater
> than what's measured at the transmitter end of the transmission line, (safely
> assuming that all transmission lines do have loss of some value or other).
> 73 Clete
> - - -
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