They are directional if you consider setting them vertically.
If placed horizontally they are not. Which could be meant as an advantage especially if laid on an attic floor which is wider than high (a bigger loop gives you better results in lower bands). BUT if mag loops are set that way, they are said lossy if the ground is less than a quarter wave below.
Why in an attic? Avoids wind load, aesthetic dispute with your neighbors, corrosion to the variable condenser and balun.
Advice: if you build one yourself ALL electrical connections must be silver soldered (every milli Ohms is worth it) 'cause high currents (up to 50 Amps), and access to the antenna should be strictly forbidden during transmit due to high voltage (10 kV or so). See AA5TB's calculator.
Not usually mentioned: this should merely be considered as a transmit antenna as your bandwidth could be as low as 2.5 kHz in lower bands. So NO panadapter with a mag loop. Just forget it. Without a panadapter of course reciprocity principle applies, but when you QSY, you quite soon won't hear anything until remote re-tuning the loop. Therefore, when in-band searching around or want to use a panadapter, you better may have a separate wideband receive antenna like Beverage or K9AY. But you're lucky: the K3(s) has a separate receive antenna input HI (just press "Rx ANT"). :)
See also the very helpful paper by the guru VK5LT:
www.brisdance.com/vk4amz/files/Download/UnderMagLoop.pdf
HTH,
Christian F1GWR
Le 22 janv. 2017 à 04:19, Robert 'RC' Conley a écrit :
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