Introduction I’m not a genius and I don’t know everything, I’m just the guy who was selected to make a presentation I’ve tried to minimize the technical theory and focus on: Practical concepts Some info not presented in textbooks Tips Techniques Because of limited time, the focus is on HF
http://www.smeter.net/propagation/sunspots/current-sunspot-cycle.php The good news: Conditions haven’t been better in 8 years!
“Propagation” refers to the travel of radio waves from point A to B A grasp of propagation theory allows you to be a more professional amateur If your radio signal does propagate, who’s out there to receive it? Propagation
Propagation: If you have it, who’s there to hear you?
SEMO ARC Demographics Extra = 20 Advanced = 6 General = 15 Technician = 12 Cape = 22 Jax = 20 Scott = 4 Other = 8
If you aren’t much interested in HF, you might not be Interested in this topic Technicians: HF Phone on 28.3 – 28.5 (worldwide) Many clubs have their own stations If we had a club HF station, who would be interested?
Terminology: HF = 3.0 – 30 MHz (80 -10 meters) VHF = 30 - 300 MHz UHF = 300 MHz - 3 GHz Propagation varies with many factors, including time of year, time of day, geographical location, solar and geomagnetic activity, weather, power, frequency, and antenna type Propagation
Radio waves belong to a family of electromagnetic radiation Family includes infrared, visible light, ultraviolet, others Radio waves, like light waves and all other forms of electromagnetic radiation, normally travel in straight directions and in all directions away from the source Propagation
Radio waves weaken as they travel, from the dispersal of radio energy from its source Range = distance a radio signal can be received Most propagation at VHF and higher frequency is usually line-of-sight, so earth curvature and obstacles are range-limiting factors HF can travel along Earth surface, “ground waves”
The ionosphere (30-260 miles high) is made up mostly of O 2 and N 2 Solar energy, in the form of ultraviolet light (UV) and X-rays going thru atmosphere can convert gas atoms to ionosphere layers of ions which can refract radio waves The ionization plays basic role in long-distance contacts in amateur bands from 1.8 MHz to 30 MHz Maximum one-hop skip is about 2500 miles. Beyond that involves multiple bounces off the ionosphere VHF and higher usually pass thru ionosphere to space D-layer: (lowest region) can absorb HF radio waves, especially 1.8 – 4.0 MHz during day
E-layer: occasionally patches of the E-layer can become overly ionized and refract even VHF and UHF, called “sporadic-E” propagation F-layers: (highest region) refracts HF, divided into two sub-groups HF refracted back to earth = “sky wave” or “skip” Highest frequency that can be refracted = MUF Lowest frequency that can be refracted = LUF “Band open” means sky waves are possible
Gray line (twilight) Radio wave-absorbing D-layer disappears faster than the higher altitude radio wave propagating F2-layer
DX Nets If you can get through to the state-side moderator, you’ll have a good chance with the DX… 1100Z : 14.2385 MHz every day 1430Z : 14.244 2000Z : 14.247 Or, call CQDX yourself
ARRL Propagation Charts (solar flux 146) MUF Line LUF Line MHz Zulu
Keep in mind that the earth is round when pointing a directional antenna (central Russia is north of here) Some times long path works best, due to the ionosphere situation between two stations, especially if short path >