New answers tagged antenna-system
3
I think the problem you will run into is that people will want this to be plug and play. They may not have a directional coupler, or know or feel like to calibrate it and all that other stuff. Even if they do it, they may wonder if they did it right and if the reading will be accurate or not. I think you will need to handle this part in your design and ...
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A part of the antenna system (system = antenna + transmission line) that is truly grounded can't radiate. Most antenna systems are more efficient when the antenna, the part that is designed to radiate, is up high. So the antenna is deliberately ungrounded. Antennas are usually designed with the assumption that the transmission line doesn't radiate much; ...
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One important reason is safety. One wants the exposed metal part of the coax connector to be at the same potential as the Transmitter case at one end, and any grounded equipment at the other end. Not at a high (RF or A/C) voltage.
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The coax shield must be at ground potential if you want the coax to function as a non-radiating transmission line. If the shield isn't at ground potential, then there will be a non-zero electromagnetic field between the coax and its surroundings. Meaning, it will radiate.
The shield could be left floating, but the shield can be grounded without changing the ...
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Assumed the frequency range of interest is up to and including shortwave then the description below is the approach. A loop antenne can be used as passive antenna with or without tuning, or as active antenna with an amplifier. Most probably your question relates to passive wideband reception antennas. Then you can read further. Active antenna can be deduced ...
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It is more than 15 years ago, that I've done it.
But if I remember correctly, the 3D screenshot you're showing is quite misleading. The pattern is drawn around the 1st antenna / center of coordinate system.
Delete the 2nd antenna and compare the gains to make sure nothing changes at all.
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Measure the inductance of the loop (without anything else connected). One winding: 2.5 uH, two windings: 10 uH (quadratic relation).
Most shortwave wideband (non-tuned) loop antennas are just a single turn. Inductance will be around 2 to 3 uH. To have constant conversion from field strength to unloaded output voltage, the short-circuited output current of ...
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If you can find out the diameter or AWG of the wire used, then you can find a resistance-per-foot (cm) chart in a Google search
If the wire is connected directly to a connector or terminals, then measure the total resistance of the coil of wire, assuming that 60 cm is the distance measured from center-to-center rather than the OD or ID.
With some simple math,...
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Take three 1/4 wave sections of 75 ohm coaxial cable (let's say RG11) and solder together. You now have a 1/4 wave section of 25 ohm. Doing the math (25 * 25) / 12.5 = 50 ohm. Now use any 50 ohm coxial cable length to the radio. Ps: don't forget to take into account the 75 ohm cable speed factor to calculate the 1/4 wave section. Good luck. Luiz PY4ACP
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There's no such thing as a "magnetic" and an "electric" wave. Only electromagnetic waves propagate – that's at the very basis of wave theory, so 1. is definitely wrong, and 2. would need rephrased to "will it produce an electromagnetic wave", and the answer to that is "yes!", otherwise it would not be an antenna.
So, ...
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