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

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

The good news: Conditions haven’t been better in 8 years!

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” 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

(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?

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 allother 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 thedispersal 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 toionosphere 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

(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

NY - Corsica

DX Cluster

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 day1430Z : 14.2442000Z : 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 >

123

Free HRD Bandscope

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

• 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?

Time Out

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RADIO WAVE PROPAGATION A REFRESHER BRIEFING

BY: RON, KØMAJ

Conclusion

CQ