HF Propagation A Guide for the Newcomer By Gary Sutcliffe
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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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