Feel free to click the links and enjoy the details presented in my wideband loop compendium update covering my experiments and learnings over the past two years.
About 18 months ago, I published a compendium of work done on magnetic loop antennas between 2014-2019. Over those five years, I started with a simple direction finding DF loop for tracking RFI, progressed through a number of remote controlled receiving loops and a wireless controlled transmitting loop for shortwaves. Finally, I arrived in the world of wideband active loop antennas.
Now it’s time for a wideband loop compendium update.
During August 2019, I summarized all the things I had learned trying to build homemade wideband loops. My early forays into designing and fabricating my own PCB amplifiers with surface mount parts went fairly well. One thing I discovered was the importance of waterproofing! None of my design-from-scratch amplifiers worked very well despite the LTSpice simulations.
So, I finally moved from my DIY boards for the early LZ1AQ design to the commercial AAA-1C active antenna amplifier. I found that the commercial LZ1AQ design works like a charm and mates perfectly with my one meter loops constructed from aluminum core PEX pipe. As the pandemic struck last spring, I began to really enjoy the great performance of wideband loops on a city lot.
Last summer, I was fortunate to obtain an SDRplay RSPduo. Now I could really experiment with coherent dual channel reception over long, medium and shortwave bands. Quickly, I added a second AAA-IC loop to my arsenal.
Wideband Loop Compendium Update – Overloads and Arrays
For the past six months, my work has focused on overloads and arrays. First, ways to manage local BCB overload when using a wideband antenna with a wideband SDR. Each software defined receiver has different designs for gain distribution and attenuation. If you live near strong medium wave transmitters, you need to figure out your best method for managing your system.
This proved relatively easy to do, but needed careful attention. Along the way, I built a dual channel wideband loop helper with switched attenuation and filtering
Lastly, in October, I designed and built a phased array with two LZ1AQ loops placed 100 feet apart. My wideband loop array works well for both directional reception (especially on MW) and RFI reduction (especially on shortwave).