Understanding VHF Propagation

This video provides a technical introduction to both common and uncommon propagation modes at VHF. Timeline: 00:00 Introduction 00:12 Presentation overview 00:44 About VHF 01:49 VHF versus HF 03:07 Why study VHF propagation? 04:12 About “line of sight” 05:02 Common VHF propagation modes 05:41 About refraction 06:28 Refractive index (N) 07:32 Tropospheric refraction and the radio horizon 08:34 About reflections 09:47 Extending range using reflections 10:31 Reflections and multipath 11:36 About diffraction 12:25 About scattering 13:19 About uncommon VHF propagation modes 14:34 Uncommon VHF propagation modes 14:51 About temperature inversions 15:33 About tropospheric ducting 16:19 Ducts and frequency 16:59 Ducting and weather 17:39 Two types of tropospheric ducts 17:54 Surface ducts 18:34 Elevated ducts 19:06 Propagation along ducts 19:32 Sporadic E 19:41 Ionospheric propagation (skywave) 20:26 Ionospheric propagation (skywave) – E layer 20:41 About Sporadic E (Es) 21:54 Mapping Es 22:28 Causes of Es and predicting Es 23:28 Es or tropospheric ducting? 24:05 Meteor burst 24:13 About meteor burst 24:57 Meteor size / velocity and ionization 25:43 Types of meteors 26:04 Shower meteors 26:54 Sporadic meteors and time of year 27:24 Sporadic meteors and time of day 28:22 Applications of meteor burst 29:34 Meteor burst: distances and frequencies 30:46 EME 30:44 The moon as a reflector 31:52 Advantages of EME 32:49 EME challenges 33:20 EME path loss 34:00 EME antennas 34:37 EME and noise 35:34 Position of the moon 36:50 Motion of the moon 38:02 Surface of the moon 39:06 EME and the ionosphere 40:02 Summary of uncommon VHF propagation modes 41:51 The (future) role of uncommon VHF propagation modes 43:07 Summary