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On 06/19/2012 11:21 AM, W5DXP wrote:
On Tuesday, June 19, 2012 5:35:57 AM UTC-5, J.B. Wood wrote: As economics professor Peter Morici would say "It isn't all that complicated." What a small shielded loop responds to should be easy to demonstrate. We know that a florescent light bulb responds mainly to the electric field because it gets brighter as one moves it from the feedpoint to the top of a mobile antenna. The standing wave voltage loop is at the top of a resonant mobile antenna. The standing wave current loop is at the feedpoint of a resonant mobile antenna. So simply take the small shielded loop and see where it responds the best up and down a mobile antenna. If some people are correct about it responding mainly to the magnetic field, the measured field strength will be highest at the base of the mobile antenna where the standing wave current is the highest. -- 73, Cecil, w5dxp.com Hello, and one has to make the distinction of whether the receiving loop is in the near or far field with respect to the source of the incident energy. A quick test is to note whether shorting or open-circuiting the terminals of the loop (or any receiving antenna for that matter) has any effect on the current flowing into the terminals of the source (transmitting) antenna. If there's no effect then the receiving antenna is most likely decoupled inductively (magnetically) and capacitively (electrically) from the transmitting antenna. What is seen as available power at the receiving antenna in that case is due to its interception of a propagating EM field. The fact that the orientation of an axis of the antenna aligns with the E or H component of an incident EM field is just a result of the applicable electrophysics. Sincerely, -- J. B. Wood e-mail: |
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