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The DB,
Sorry, not true at all. Don't confuse radiation resistance with impedance.
Use a 1/2 wave length antenna that's resonant. If fed in the center the input impedance should be in the neighborhood of 50 - 75 ohms. If fed at one end, that input impedance will be in the neighborhood of 1000+ ohms. The radiation resistance of that 1/2 wave length antenna has not changed, neither has it's resonance.
How about the input impedance of a 5/8 wave vertical antenna? It's input impedance isn't 50 ohms by any means until it's been matched by an impedance matching device of some kind.
That radiation resistance is -part of- input impedance and it's value is almost never 50 ohms or really close.
- 'Doc

[QUOTE="W5LZ, post: 396816, member: 129"] The DB, Sorry, not true at all. Don't confuse radiation resistance with impedance. Use a 1/2 wave length antenna that's resonant. If fed in the center the input impedance should be in the neighborhood of 50 - 75 ohms. If fed at one end, that input impedance will be in the neighborhood of 1000+ ohms. The radiation resistance of that 1/2 wave length antenna has not changed, neither has it's resonance. How about the input impedance of a 5/8 wave vertical antenna? It's input impedance isn't 50 ohms by any means until it's been matched by an impedance matching device of some kind. That radiation resistance is -part of- input impedance and it's value is almost never 50 ohms or really close. - 'Doc [/QUOTE]

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