 He died at Buckhurst Hill, aged 85.Franklin received British patent 242342 in 1924 for "a pronounced directional effect from aerials of the type that are electrically long in comparison with the signal wavelength".The antenna is so physically tall (about 1,813 feet at 540 kHz, and about 612 feet at 1600 kHz) that its use is generally restricted to frequencies of 1400 kHz and above, with one example at 1500 kHz (KSTP, St. Paul, MN, non-directional, daytime only) and two examples at 1530 kHz (KFBK, Sacramento, CA, directional day and night using different parameters day and night).