[Antennas] VSWR on Log Periodic.

[George, W5YR]

Ron W7MRR wrote:

>    While it is true that a high SWR means less power radiating from the antenna, low SWR doesn't necessarly mean the opposite.

Have to be careful with this one, Ron. It all depends upon the feedline
loss, doesn't it? I can have a 20:1 SWR in a real open-wire line and have a
power loss of perhaps 0.2 db. Virtually every watt put into the feedline is
radiated by the antenna despite the "high SWR."

On the other hand, a coax line with a 20:1 SWR of any appreciable length
could lose half or more of the input power, especially at the higher
frequencies.

So, while it is *sometimes* true "that a high SWR means less power
radiating from the antenna" it is not *always* true.

You are spot on with the rest of that sentence, though!   <:}

Low SWR can mean either that the antenna and feedline are well matched with
minimal added mismatch line loss or it can equally well mean that the line
is very lossy and thus tends to minimize the effect of the true antenna
driving-point impedance and persuade the unwary operator that "everything
is fine."

73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
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