Youtor
Johnny Madsen Færgemand
>> YOUR LINK HERE: ___ http://youtube.com/watch?v=DTXJ3bS2UcE
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
#############################
