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Hi, Jim, yes. In fact if you look in your User Manual at the page titled "Electrical and mechanical specifications" on the bottom right-hand side is the loop radiation pattern and on the left-hand side is a drawing of the loop, and the "Front" is marked.
73, Adrian 5B4AIY
I think so Adrian, thanks! So I need to work out which direction the gamma match is pointing to work out the ‘front’ which continuing the wheel analogy, is the direction of travel (at 90 degrees to the axle). Therefore the arrow pointing ‘Front’ in the manual IS -at right angles to what I described is looking through the loop (ie directly into the empty space in the circle). That helps massively! Thanks!
Hi, Jim,
I'm not sure what you mean, but let's see if I can help. Because the loop uses a gamma match to feed power into the loop this results in a certain amount of asymmetry in the radiation pattern. If you look in your User Manual you will see that at low radiation angles, <30 degrees, the front-to-back ratio is about 1 S-point, or 6dB. This is in the plane of the loop, and the "front" or forward direction is along the gamma match in the direction in which it is pointing. The "back" or reverse direction is away from the gamma match. At right-angles to the loop, in other words, if the loop were a wheel, in the direction of the axle shaft, there is a deep null, about 20dB, which can be used to reject a low-angle interfering signal. Note that at higher radiation angles, >40 degrees, the radiation pattern is almost omnidirectional, which means that high-angle signals will be received equally in all directions. In the case of a beam antenna, it is common practice to rotate the beam to maximise the received signal, in the case of a magnetic loop it is more advantageous to rotate to loop to maximise the received signal-to-noise ratio. Hopefully this clarifies it for you.
73, Adrian, 5B4AIY