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Although the basic concepts and principles are sound, things have moved on over the 40+ years that have passed since the articles were published. Regards, Martin

Ralph Burhans wrote an excellent series of antenna articles in Radio Electronics in 1983:? ?February 1983, part 1 - All about VLF Active Antennas? ?March 1983, part 2 - All about VLF Active

Well, the truth be known, I mostly use the 0.5-meter "shielded" loop for DF'ing RFI. It's great for that. But, yes, the null is bidirectional. Dave - W?LEV [email protected]> wrote: -- *Dave

Hi Dave.. totally agree..when comes to antennas I hate to buy!! However, not all feel the need to do so, or have the time to do. (Dave you are on rsgb technical, you have no doubt seen my thread

Understand, Simon. In retirement, US $$$$ are not an option for me. That's why, whenever possible, I build my own. Dave - W?LEV [email protected]> wrote: -- *Dave - W?LEV*

Hi Bill ( and Dave) Bill has paid a good few bucks for the Azi-loop if its from UK, so wants it to work as advertised.( if not a knock off.) It should av a better f/b than that. But Bill remember

If you are searching for nulls, I find a "shielded" 0.5-meter loop made of 0.5-inch copper tubing hard to beat. Five internal turns, the center of which is cut and brought out to a home brew and

363 930 1030 610 khz. 73, Bill, WA2DVUCape May, NJ

Hi Bill On what frequencies? Simon g0zen

Hi Martin, Thank you very much for the explanation, it all makes sense. Yes I was thinking flat plate antenna. Mikek

A tour de force by Chris Trask!! Re my previous suggestion of using constant current sources replacing R1 and R2 in Everett's great circuit, I leave the following quote by Chris.... lower (Q1). This

Hi Hisami, This is the paper the design was taken from. http://www.kiwisdr.com/docs/Complementary%20Push-Pull%20Amplifiers.pdf Regards, Martin

Hi Bill, I suggest you model your exact antenna and radial dimensions in eznec and check f/b at 2 degrees. Try optimising the f/b with a resistor 100-600 ohms in series with insulated radials on their

Hi Martin, Thanks for the infomation and advices. Thanks also for the recommend on "Chris Trask (fig.5)". I will look for the FETs. I have several pairs, but they all seem to have large Ciss. tnx &

I have just installed an Aziloop and I do not get good nulls - 10 -15 dB on 50 -100-mile ground wave signals, Loop is 13' on long side, 8' on short side and PVC mast is 15 feet. Radials are on the

Hi ?Mikek, The better IMD performance of the Trask circuit, means that it can be used with a larger antenna (one having greater self capacitance) such as a 1m whip. The coax transmission line forms

I have a question about the Trask push-pull amplifier. Doesn't it have a rather low input impedance to be connected to a probe antenna? Mikek

Hi Hisami, The PA0RDT https://owenduffy.net/antenna/PA0RDT-MiniWhip/ PA3FWM http://www.pa3fwm.nl/projects/miniwhip/ PA0NHC dual fet https://www.pa0nhc.nl/Miniwhip_20180416/index.htm Are probably the

Hi I have uploaded some pictures to my blog. https://www.7l4iou.com/2025/03/kp901b.html I will add circuits and descriptions. If I get enough results to introduce them. 73, Hisami 7L4IOU

The AMRAD active antenna is based on Burhan's circuit. https://www.arrl.org/files/file/Technology/tis/info/pdf/0109031.pdf W1VD also has a version using a common J310 jfet.