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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

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Presentation Transcript
slide3
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
slide4
The good news: Conditions haven’t been better in 8 years!

http://www.smeter.net/propagation/sunspots/current-sunspot-cycle.php

slide7
Example of actual current propagation

Today on 10 Meters:

England station , 100 W, 20-foot beam, S-9 +10

(S-3 on dipole)

slide9
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?
slide11
SEMO ARC Demographics
  • Extra = 20
  • Advanced = 6
  • General = 15
  • Technician = 12
  • Cape = 22
  • Jax = 20
  • Scott = 4
  • Other = 8
slide13
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?
slide18
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
slide20
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
slide21
Radio waves weaken as they travel, from the
  • dispersal of radio energy from its source
  • Range = distance a radio signal can be received
  • Mostpropagation 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”
slide23
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
  • D-layer: (lowest region) can absorb HF radio waves,
  • especially 1.8 – 4.0 MHz during day
slide25
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
slide26
Gray line (twilight)
  • Radio wave-absorbing D-layer disappears faster than the higher
  • altitude radio wave propagating F2-layer
slide29
Band Plans (ARRL) (Beacons)
  • QRP stations with CW ID
  • If you need CW help, get a CW program from
  • SEMOARC.net links
slide32
DX Cluster

NY - Corsica

slide34
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
slide36
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 >
slide38
3

2

1

slide39
Free HRD Bandscope

Various propagation programs available: Google: “radio propagation software”

slide40
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

New York

Alaska

Iowa

Hawaii

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