On Wednesday, November 28, 2012 5:50:28 PM UTC-6, Channel Jumper wrote:
The regular MFJ 949 series tuner was usually employed - although most
people do not understand that it cannot make a non resonant antenna
resonant.

Apparently, some people don't understand the maximum power transfer theorem.. An antenna tuner establishes a Z0-match to 50 ohms, commonly called "making the transmitter happy". If the antenna system is a low-loss system, the effect of that Z0-match in the shack is a near-conjugate match at the antenna feedpoint which guarantees maximum transfer of available power to the antenna. It doesn't matter if the antenna by itself is resonant or not. Conjugately matched *systems* ARE resonant.

Let's assume we have a non-resonant antenna with a feedpoint impedance of 100+j200 ohms. If we feed the antenna with open-wire line and adjust the antenna tuner in the shack such that the impedance looking back down the transmission line towards the source is 100-j200 ohms, the reactance is neutralized, i.e. *system resonance* is established with an apparent 100 ohm source and 100 ohm load thus ensuring maximum transfer of available power.

The well-respected Extended Double Zepp is an example of a non-resonant antenna that will outperform a resonant 1/2WL center-fed dipole in the dipole's favored direction. Note: with the feedline disconnected, a 1/2WL center-fed dipole is non-resonant. Connecting the coaxial feedline resonates the antenna system just as connecting a properly tuned open-wire feeder resonates the antenna system.

Consider a 50 ohm 1/2WL resonant center-fed dipole fed with 1/2WL of open-wire line. The SWR on the feedline is 12:1, i.e. a severe impedance mismatch exists at the antenna feedpoint. Yet, the transmitter sees 50 ohms and this mismatched system is more efficient than most coax-fed antenna systems.
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73, Cecil, w5dxp.com