Trivia question

How many feet of rg59 coaxial cable would it take to present a 50 ohm load to your transmitter assuming a 50 ohm load is connected to the other side?
I assume Ridgeline knows the answer to this question

 

One more trivia question. When is a 9:1 SWR a perfect match?

 

If nobody gets it right I'll post the answer sometime tonight

 

The answer to both of those questions is in this book

 

a half-
wavelength of any impedance transmission line faithfully
reproduces the impedance of the load (minus losses). With
a 50 ohm antenna and no losses in the transmission line,
the following is true.

Transmission line SWR Impedance seen at the transmitter

1/2 WL of 50 ohm 1:1 50 ohms
1/2 WL of 75 ohm 1.5:1 50 ohms
1/2 WL of 300 ohm 6:1 50 ohms
1/2 WL of 450 ohm 9:1 50 ohms

So you see a half-wave section matches the impedance of the
antenna regardless of the magnitude of the SWR. If the SWR
is anything other than 1:1, a half-wavelength (or multiple)
is the *only* length that will match the 50 ohms of the
antenna.


180° of ladder line looks like :
Swr 9:1
R=50
Perfect match
Surprised nobody figured it out

Per the ARRL Antenna Book, 17th ed., p. 24-12:
"When the line length is an even multiple of 90° (that
is, a multiple of ? wavelength), the input resistance
is equal to the load resistance, regardless of the
line Zo... It does not matter whether the impedence
...is resistive, reactive, or a combination of both."