In my location with poor ground conditions, the K9AY loop seems to offer the best performance. This site discusses the design and implementation of 2- and 3- and 4- element endfire arrays of K9AY loops. Design of these arrays focuses on optimization of the Receiving Directivity Factor or RDF attributed to W8JI (See the Low-Band DXing book by ON4UN).
As with most multi-element arrays, addition of the second element makes the largest improvement in performance, approximately 3 dB. The addition of a 3rd and 4th element each improves the RDF by approximately 2 more dB.
Design design details can be found on the K9AY Loop Array page.
You can contact Dick at: firstname.lastname@example.org
2. Gary Breed, K9AY, "The K9AY Terminated Loop - A Compact, Directional Receiving Antenna," QST, pp. 43-46, September 1997.
3. Hi-Z Antennas by Lee Strahan, K7TJR and Dick Ewing, KO7N: http://www.hizantennas.com
4. Wellbrook Communications, The Wellbrook K9AY Phased Array 500 kHz, to 2 MHz: http://www.wellbrook.uk.com/K9AYphasedarray.html
5. Richard C. Jaeger, "Multi-Element End-Fire Arrays of K9AY Loops," QEX, pp. 22-31, January/February 2013.
Dick was first licensed as KN4IQJ in the summer of 1959 and upgraded a
few months later. He is primarily a CW operator who enjoys chasing DX
and operating in contests, particularly on the low bands. He has worked 352 countries, is on top
of the SSB/Mixed Honor Rolls, needs only P5 on CW, and has competed CQ
5BWAZ. He has worked 264 countries and 38 zones on 160M and 313 countries on 80M.
QSLs for all these operations should be sent to K4IQJ direct or via the bureau. - - - - - In his other life, he is Distinguished University Professor Emeritus of Electrical and Computer
Engineering at Auburn University. He founded the Alabama
Microelectronics Center in 1984 and served as its director through 1998.
From 2004-2007 he led implementation of Auburn University’s Wireless
Engineering Degree Program, the first ABET Accredited undergraduate
wireless engineering degree in the US.
He is an IEEE Life Fellow, Past President of the IEEE Solid-State Circuits
Society, past Editor of the IEEE Journal of Solid-State Circuits, and a
Past Chair of both the International Solid-State Circuits Conference
(ISSCC) and the International VLSI Circuits Symposium. He was also
Founding Editor of IEEE Micro Magazine.
Dr. J. is author of the Addison Wesley text Introduction to
Microelectronic Fabrication, 2E, and co-author of Microelectronic
Circuit Design, 5E, published by McGraw-Hill. He received the 2004 IEEE
Undergraduate Teaching Award.