RADIO WAVE PROPAGATION
A REFRESHER BRIEFING
BY: RON, KØMAJ
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
The good news: Conditions haven’t been better in 8 years!
http://www.smeter.net/propagation/sunspots/current-sunspot-cycle.php
Not so good news…
Example of actual current propagation
Today on 10 Meters:
England station , 100 W, 20-foot beam, S-9 +10
(S-3 on dipole)
Propagation
• “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: 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
(Wikipedia)
• 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?
Propagation
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
• 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 O2 and N2
• 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
(DX net example including Louri)
• 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
WWV
Band Plans (ARRL) (Beacons)
• QRP stations with CW ID
• If you need CW help, get a CW program from
SEMOARC.net links
Audio splitter to your computer
DX Cluster
NY - Corsica
Contests
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)
MHz
MUF Line
LUF Line
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 >
3
2
1
Free HRD Bandscope
Various propagation programs available: Google: “radio propagation software”
Time Out
• I’m out of time (and ideas)
• You can view or download this presentation from
the “Links” section of SEMOARC.NET (viewer)
• Questions / Comments / Discussions?
Japan
Hawaii
Alaska
Iowa
New York
RADIO WAVE PROPAGATION
A REFRESHER BRIEFING
BY: RON, KØMAJ
Conclusion
CQ