Four-Course Radio Range, Whitmore, CA, 2019
Located 5 miles west of Whitmore, California, this is one of the few remaining four-course radio range locations. Wooden poles were used instead of steel antennas because metal would have interfered with the pattern created by the loop antennas. Eventually, these were replaced by the VOR.
40°37’30.88″N 121°59’48.60″W

Early low-frequency radio station (such as the above photo) based on crossed loop antennas; later installations used Adcock antennas for improved performance.