Transcript HF Propagation A Guide for the Newcomer By Gary Sutcliffe

HF Propagation
An Introduction for the Newcomer
By
Gary Sutcliffe, W9XT
Copyright (c) 2008 Gary C. Sutcliffe
Topics
 What are the HF Bands?
 How HF Propagation works
 Band by Band Overview
 Operating HF
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Amateur Bands
 A range of frequencies.
 Different modes allowed on different frequency ranges of
the band
 Usually referred to by wavelength i.e. “40 Meters”
 Historical – in early days of radio wavelengths were used
to designate frequency
 Wave length = 300/frequency in MHz
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The High Frequency Bands
HF ranges from 3-30 MHz
Traditional Bands
WARC Bands
 160M* 1.80-2.00 MHz
 30M 10.10-10.15 MHz
 80M
 17M 18.068-18.168 MHz
3.50-4.00 MHz
 40M 7.00-7.30 MHz
 20M 14.00-14.350 MHz
 15M 21.00-21.450 MHz
 10M 28.00-29.700 MHz
 12M 24.890-24.990 MHz
*Technically MF
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The Ionosphere
 Caused when UV light knocks electrons off air
molecules
 Varies with
 Solar flux (number of sunspots)
 Season
 Time of day
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HF Propagation Via the Ionosphere
MUF – Maximum Usable Frequency
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Ionosphere Layers
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D Layer
 Caused by UV light
 Forms during the day
 Disappears at night
 Absorbs lower frequency signals
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E Layer
 Thought to be caused by wind shear
 Not usually there
 Can last minutes to hours
 Most common May-July
 Can be very intense
 Usually effective 50 MHz (6 Meters) and below
 Rare at 144 MHz (2 Meters) and above
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F Layer
 Responsible for most HF propagation
 Caused by UV light from sun
 Forms during day, dissipates at night
 MUF varies with ionization level
 Sometimes splits into F1 and F2 during the day
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Ionization and the Sun
 Ionization level corresponds closely to sun spots
 Sun spots follow an 11 year cycle
 Sun spots
 range from 0 to ~ 150
 Smoothed number used
 Solar flux – 10.7 cm radiation
 Ranges from ~60 to ~250
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Geomagnetic Field
 Indicates stability of magnetic field of Earth
 Reported as A & K indices
 A Planetary index
 K single site
 Low index = stable / high index = unstable
 Solar flares cause high A & K
 High A & K
 often result in auroras
 absorption of radio waves on polar paths
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Propagation Numbers
 Sources
 WWV 18 minutes after the hour
 Various Internet sites
 High SF (solar flux) means higher MUF
 Need high numbers for 10 & 15 Meters to open
 Lower levels best for 160 & 80 Meter DXing
 Low A & K mean Geo-magnetic field stability
 Needed for polar paths (mid-west USA to Europe,
Japan)
 North-South paths not affected as much by
geomagnetic field
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Paths Radio Wave Follow
 Normally follows great circle path
 Long path – the long way around the world
 Most common on 40 - 15 Meters
 Back Scatter – no direct path open
 Signals scatter off area with common propagation
 Gray Line
 Low frequency signals follow terminator
 Sunrise or sunset at each end
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Sporadic E (Es)
 Can happen any time
 Most common May-July
 Secondary peak period Dec-Jan
 Most apparent on 10 Meters
 Up to ~1500 miles, multi-hop possible
 Openings can be very localized or wide spread
 Can result in very strong signals
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160M
 Day – Local to a few hundred miles
 Night – Long distances possible
 Often noisy (static)
 A very challenging DX band
 Antennas difficult because of size – Dipole ~260'
 Technician: No operation permitted
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80 Meters
 Day – Local to several hundred miles
 Night – World wide possible
 Often noisy (static)
 Challenging DX band
 Phone band sometimes called 75 Meters
 Popular band for nets
 Antennas difficult in small lot – Dipole ~ 133'
 Technician: CW
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40 Meters
 Day – Local to 1000 miles or more
 Night – World wide possible
 A reliable band – almost always open somewhere
 Antennas manageable
 Dipole ~ 66'
 Verticals with good radials effective DX antenna
 Beams large but manageable with heavy duty rotor
 Technician: CW
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30 Meters
 Day- 1000 miles or more
 Night - World wide possible
 Similar to 40M
 Antennas manageable
 Dipole ~46'
 Vertical very effective DX antenna
 WARC Band, CW & Data only, 250W max
 Technician: No operation permitted
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20 Meters
 Day – 500 miles to world wide
 Night -World wide possible
 Considered by some as best DX band
 Antennas manageable
 Dipole - ~33'
 Beams common
 Technician: No operation permitted
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17 Meters
 Day - hundreds of miles to world wide
 Night – open world wide with high sunspot levels
 Good band for beginning DXer
 Antennas
 Dipole ~ 25'
 Beams manageable
 WARC Band
 Technician: No operation permitted
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15 Meters
 Day – Hundreds of miles to world wide
 Night – Stays open late with high sunspot levels
 Great DX band in moderate-high sunspot years
 Antennas
 Dipole ~22'
 Beams common
 Technician: CW
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12 Meters
 Day - Hundreds of miles to world wide
 Night – open only in high sunspot years
 Great DX band in high sunspot years
 Antennas
 Dipole ~18'
 Beams helpful
 WARC Band
 Technician: No operation permitted
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10 Meters
 Day - Hundreds of miles to world wide
 Night – open several hours in high sunspot years
 Excellent DX band in high sunspot years
 Very quiet
 Modest stations effective
 Very large – stations can spread out to avoid QRM
 Antennas
 Dipole ~18'
 Beams common
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10 Meters (continued)
 Many propagation modes
 F (with moderate to high sunspot levels)
 Es
 Aurora
 Technician: CW, data, phone
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HF Operating Activities
 Rag chewing
 DXing
 Contesting
 Awards – DXCC, WAS, WAC, etc.
 Special event stations
 Nets – Formal & Informal
 Modes: SSB, CW, RTTY, PSK31, SSTV, more
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Operating HF
 Three rules for HF operating
 Listen
 Listen
 Listen
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HF Operating (continued)
 Operation not channelized
 Watch band edges!
 No one owns a frequency
 Avoid interfering with other stations
 Ask if a frequency is in use before transmitting
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Phone operation
 Single Side Band (SSB)
 Lower Side Band (LSB)160, 80 & 40
 Upper Side Band (USB) 20, 17, 15, 12, & 10
 Watch band edges
 Low end on LSB
 High end on SSB
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Phone Operation (continued)
 Learn and use standard phonetics for call signs
 Use full call signs for ID
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HF QSOs
 Normally start with a CQ
 Keep CQs short, 3 X 3 is fine
 Answer CQ with his call sign followed by yours 1-2
times
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DX QSOs
 Follow his lead – don't attempt to rag chew if he is
only handing out signal reports.
 Listen and follow his instructions for calling
 In a pile up give your full call sign once
phonetically then listen
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Learning Propagation
 Get on the air!
 Get on different bands at different times
 NCDXF Beacons
 http://www.ncdxf.org/beacons.html
 Beacons on 20, 17,15, 12 & 10 meters
 Propagation Prediction Programs
 W6EL
 ITS HF Prop
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Learning Propagation (continued)
 Operating activities that help learn propagation
 Work on awards


Worked All States
DXCC – work 100 countries
 Contests

The increased activity gives a good indication of band
openings
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Summary
 HF provides a life time of challenges and fun
 Opens the whole world
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