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garyspang
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Joined: 11 Mar 2018
Posts: 5
Location: Clemson area, South Carolina

 Posted: Sun Apr 15, 2018 8:39 pm    Post subject: does the measured power actually leave the antenna? Power flow: (Transmitter output) to (40ft of 50 ohm coax) to (very high resolution Auto-tuner) to (1:4 step-up transformer) to (32ft vertical antenna and 30ft motor-home chassis ground). Measurement: The applied frequency is 1.9 MHz. At the transmitter output, a Bird watt-meter reads 105 Watts out and 2.5 Watt reflected (VSWR ~1.4). The loss is about 2.8%. Without the Auto-tuner the transmitter protection folds back to 8 watts out and 8 watts are reflected (VSWR ~infinity). The loss is about 100%. Question: I know the tuner is presenting the antenna with its complex conjugate. Does this also mean that 97.2% (less any tuner/transformer losses) of the applied power of 105 Watts is now actually leaving the antenna? Thanks for helping me with this mystery.

Joined: 03 Jan 2007
Posts: 210

 Posted: Mon Apr 16, 2018 6:29 pm    Post subject: If your antenna has VSWR of 1.4, then yes, 97.2% is delivered to the antenna. How much is radiated depends on your antenna efficiency: http://www.antenna-theory.com/basics/efficiency.php Many antennas have efficiencies above 90%, so of the power delivered to the antenna, if the design is good then most of the power is radiated.
martintolley
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Joined: 23 May 2018
Posts: 1
Location: Hoa K&#7923;

 Posted: Wed May 23, 2018 7:47 am    Post subject: This topic is so much helpful topic.Thanks admin to giving this topic.And also thanks other users geometry dash
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