Very low frequency (VLF) describes signals in the frequency range of 3 to 30 kHz. This video provides a short technical introduction to VLF and VLF propagation, including a discussion of how and why VLF is used for communication with submarines.
Learn about propagation and communication applications at HF and VHF: https://www.rohde-schwarz.com/us/campaigns/adt/hf-learning-center_253628.html
Test and Measurement Fundamentals playlist: https://www.youtube.com/playlist?list=PLKxVoO5jUTlvsVtDcqrVn0ybqBVlLj2z8
Timeline:
00:00 Introduction
00:15 About VLF (very low frequency)
01:28 VLF propagation modes
01:48 VLF surface wave propagation
02:42 VLF skywave propagation
03:41 VLF propagation variation
04:50 About sferics
05:51 About diurnal effects
06:42 VLF antennas
07:37 VLF antenna sites / ground plane
08:23 Example – US Navy Site at Culter, Maine
09:11 Modulation used at VLF
10:16 VLF for submarine communications
11:12 Example: TACAMO (Take Charge and Move Out)
12:04 Dual trailing wire antenna (DTWA)
12:36 Deploying a DTWA antenna
13:23 Summary