Is that an eggbeater on my fence? No, it’s my new crossed wideband loops configuration for easily switching directions.
A great feature of my LZ1AQ active antenna amplifier is the ability to use two loops. Up until now, I have used my amplifier with one-meter aluminum loops, either in single loop or dual loop configuration.
Running two loops in a single plane provides lower loop inductance and signal-to-noise improvement. But crossing the loops, as shown above, provides a switched directional antenna. Next to a rotatable loop, this might be an ideal configuration.
As you recall, wideband loops have some directivity in their plane, and a great deal of null broadside. Placing two loops in an orthogonal (90°) offset minimizes their interaction and places two nulls 90° apart. This is especially useful if your local noise has a similar arrangement.
As you switch between these loops on your SDR, you will also notice some decent signal level changes, especially on lower frequencies like Medium Wave. I will do some listening on this configuration for a while and report back.
I still intend to build a 1.7 MHz High Pass Filter to knock down local broadcast band overload. That’s going to be my first CNC-PCB project shortly.
Crossed Wideband Loops Mounting Arrangement
Here’s a quick look at how I mounted the crossed loops.
I call this my 3D printed orthogonal loop mount. Basically, I designed two identical plastic loop holders that can plug into each other (or a separate base) at 90° angles. You will see that it is all friction fit, but a bit of glue can be added for more confidence. I find that either PLA or PETG works for these kinds of projects, but PETG is definitely preferred for durability across temperature ranges.
Nice thing about my new Prusa i3 MK3S printer is the ability to print to pretty fine tolerances, such as a 0.2 millimetre fit.
As a final note, when I had everything apart I was able to confirm that the LZ1AQ amplifier box had remained waterproof.