New answers tagged

2

Below is a rough estimate of the near fields calculated by NEC4.2 for an elevation of 3 meters above level Earth from a transmit antenna and system as generally described in the OP, and the followup comments of the OP. "Use with due diligence."


3

Estimating the near field is best done with modeling software or empirical measurement. The details of the antenna construction and environment (the ground and any nearby conductive objects in particular) can significantly impact the near field. That said, 100W is not much, and often regulations specify that no particular evaluation need be done if the ...


4

From my informal results based on the reception of medium-wave AM broadcast stations on a Tecsun PL-310 "Ultralight" receiver, the dBµ signal strengths displayed on the receiver were over 6 dB greater when the receiver was held at ~5' AGL next to the trunk of a large, isolated oak tree than when 10+ feet away from it. In all test locations the physical ...


1

"Does the fact that the reflected waves on the antenna are in phase with the applied signal result in zero reactance at the feed point, or does zero reactance happen for some other reason?" The short answer to your question is, "Yes." It is helpful to think of the dipole antenna as an open-circuited two-wire transmission line whose conductors have been ...


4

You can experimentally 'ball park' the location of the focus, visually, several ways, by using sunlight. One example -- some have temporarily attached (double-sided tape?) about a dozen one inch square mirrors in the dish, or reflective tape, from rim to center, and along say four radial lines from the center (if by the clock, at 12, 3, 6, 9 o'clock). Then ...


Top 50 recent answers are included