" ADA" : An Active Differential Antenne For 5Hz – 500 KHz by I1RFQ
This article describe the design, construction, measurements and receiving experiences made with such “exotic”antenna that fully covers ELF – SLF – ULF – VLF - LF and part of the MF.
http://www.vlf.it/cr/differential_ant.htm

472 kHz Antenna by M1GEO
I started writing an ERP calculator for low and medium frequency, though it would cover any electrically short antenna.
https://www.george-smart.co.uk/radio/472_khz/472_khz_antenna/

630m loaded inverted L Antenna by VK5FQ
Again,yes. It is possible to put up loaded antenna for the 630m Ham band in a suburban backyard. As stated before, if you have a suitably located tree or two and/or a flagpole or like, then go for it.
http://www.spirat.com.au/vk5fq/630mAnt.html

A Broadband Shielded Receiving Loop for LF DX Work by VE7SL
This is a description of a broadband ( ~40kHz - 500kHz) shielded receiving loop and preamplifier suitable for low-noise LF reception. The preamplifier was originally developed by the late Ralph Burhans, a dedicated engineer and LF experimenter.
http://qsl.net/ve7sl/burhans.html

Magnetic loop receive antenna by PA3BCA
Today I built and placed a magnetic loop receive antenna in the backyard, replacing (for now) the pa0rdt miniwhip I used until July this year. (Between July and today I have not been active on 500 Khz....).
http://pa3bca.nl/index.php?option=com_content&view=article&id=10&Itemid=14

New LF / MF Loop by VE7SL
The new 'loop' is not really loop-shaped but is rectangular (10' x 20') and more like a Flag antenna shape. I considered a Flag but really don't need any back-end nulling capability since I'm mainly interested in listening to the east and to the north.
http://ve7sl.blogspot.com/2014/10/new-lf-mf-loop.html

A Homebrew 11.7 uHy Variometer by W5JGV
I needed a simple variometer to be able to vary the inductance in the matching network for my 600 Meter vertical antenna. After considering several options, I decided to build a variometer using some easily obtainable parts. The variometer described here allows a +/- 5.85 uHy swing while inserting a fixed 6.1 uHy inductance in the system.
http://w5jgv.com/11.7uHy_Delta_Variometer/index.htm