Upload
jaiden-larter
View
220
Download
3
Embed Size (px)
Citation preview
HF PropagationAn Introduction for the Newcomer
ByGary Sutcliffe, W9XT
Copyright (c) 2008 Gary C. Sutcliffe
TopicsWhat are the HF Bands?How HF Propagation worksBand by Band OverviewOperating HF
2W9XT
Amateur BandsA 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 frequencyWave length = 300/frequency in MHz
3W9XT
The High Frequency BandsHF ranges from 3-30 MHz
Traditional Bands WARC Bands160M* 1.80-2.00 MHz80M 3.50-4.00 MHz40M 7.00-7.30 MHz20M 14.00-14.350 MHz15M 21.00-21.450 MHz10M 28.00-29.700 MHz
*Technically MF
30M 10.10-10.15 MHz
17M 18.068-18.168 MHz
12M 24.890-24.990 MHz
4W9XT
The IonosphereCaused when UV light knocks electrons off
air moleculesVaries with
Solar flux (number of sunspots)SeasonTime of day
5W9XT
HF Propagation Via the Ionosphere
MUF – Maximum Usable Frequency
6W9XT
Ionosphere Layers
7W9XT
D LayerCaused by UV lightForms during the dayDisappears at nightAbsorbs lower frequency signals
8W9XT
E LayerThought to be caused by wind shearNot usually there
Can last minutes to hoursMost common May-July
Can be very intenseUsually effective 50 MHz (6 Meters) and
belowRare at 144 MHz (2 Meters) and above
9W9XT
F LayerResponsible for most HF propagationCaused by UV light from sunForms during day, dissipates at nightMUF varies with ionization levelSometimes splits into F1 and F2 during the
day
10W9XT
Ionization and the SunIonization level corresponds closely to sun
spotsSun spots follow an 11 year cycleSun spots
range from 0 to ~ 150Smoothed number used
Solar flux – 10.7 cm radiationRanges from ~60 to ~250
11W9XT
Geomagnetic FieldIndicates stability of magnetic field of
Earth Reported as A & K indices
A Planetary indexK single site
Low index = stable / high index = unstableSolar flares cause high A & KHigh A & K
often result in aurorasabsorption of radio waves on polar paths
12W9XT
Propagation NumbersSources
WWV 18 minutes after the hourVarious Internet sites
High SF (solar flux) means higher MUFNeed high numbers for 10 & 15 Meters to openLower levels best for 160 & 80 Meter DXing
Low A & K mean Geo-magnetic field stabilityNeeded for polar paths (mid-west USA to
Europe, Japan)North-South paths not affected as much by
geomagnetic field
13W9XT
Paths Radio Wave FollowNormally follows great circle pathLong path – the long way around the
worldMost common on 40 - 15 Meters
Back Scatter – no direct path openSignals scatter off area with common
propagationGray Line
Low frequency signals follow terminatorSunrise or sunset at each end
14W9XT
Sporadic E (Es)Can happen any time
Most common May-JulySecondary peak period Dec-Jan
Most apparent on 10 MetersUp to ~1500 miles, multi-hop possibleOpenings can be very localized or wide
spreadCan result in very strong signals
15W9XT
160MDay – Local to a few hundred milesNight – Long distances possibleOften noisy (static)A very challenging DX bandAntennas difficult because of size – Dipole
~260'Technician: No operation permitted
16W9XT
80 MetersDay – Local to several hundred milesNight – World wide possibleOften noisy (static)Challenging DX bandPhone band sometimes called 75 MetersPopular band for netsAntennas difficult in small lot – Dipole ~
133'Technician: CW
17W9XT
40 MetersDay – Local to 1000 miles or moreNight – World wide possibleA reliable band – almost always open
somewhereAntennas manageable
Dipole ~ 66'Verticals with good radials effective DX antenna Beams large but manageable with heavy duty
rotorTechnician: CW
18W9XT
30 MetersDay- 1000 miles or moreNight - World wide possibleSimilar to 40MAntennas manageable
Dipole ~46'Vertical very effective DX antenna
WARC Band, CW & Data only, 250W maxTechnician: No operation permitted
19W9XT
20 MetersDay – 500 miles to world wideNight -World wide possibleConsidered by some as best DX bandAntennas manageable
Dipole - ~33'Beams common
Technician: No operation permitted
20W9XT
17 MetersDay - hundreds of miles to world wideNight – open world wide with high sunspot
levelsGood band for beginning DXerAntennas
Dipole ~ 25'Beams manageable
WARC BandTechnician: No operation permitted
21W9XT
15 MetersDay – Hundreds of miles to world wideNight – Stays open late with high sunspot
levelsGreat DX band in moderate-high sunspot
yearsAntennas
Dipole ~22'Beams common
Technician: CW
22W9XT
12 MetersDay - Hundreds of miles to world wideNight – open only in high sunspot yearsGreat DX band in high sunspot yearsAntennas
Dipole ~18'Beams helpful
WARC BandTechnician: No operation permitted
23W9XT
10 MetersDay - Hundreds of miles to world wide Night – open several hours in high sunspot
yearsExcellent DX band in high sunspot years
Very quietModest stations effectiveVery large – stations can spread out to avoid
QRMAntennas
Dipole ~18'Beams common
24W9XT
10 Meters (continued)
Many propagation modesF (with moderate to high sunspot levels)Es
AuroraTechnician: CW, data, phone
25W9XT
HF Operating ActivitiesRag chewingDXingContestingAwards – DXCC, WAS, WAC, etc.Special event stationsNets – Formal & InformalModes: SSB, CW, RTTY, PSK31, SSTV,
more
26W9XT
Operating HFThree rules for HF operating
ListenListenListen
27W9XT
HF Operating (continued)Operation not channelizedWatch band edges!No one owns a frequency
Avoid interfering with other stationsAsk if a frequency is in use before
transmitting
28W9XT
Phone operationSingle Side Band (SSB)
Lower Side Band (LSB)160, 80 & 40Upper Side Band (USB) 20, 17, 15, 12, & 10
Watch band edgesLow end on LSBHigh end on SSB
29W9XT
Phone Operation (continued)Learn and use standard phonetics for call
signsUse full call signs for ID
30W9XT
HF QSOsNormally start with a CQKeep CQs short, 3 X 3 is fineAnswer CQ with his call sign followed by
yours 1-2 times
31W9XT
DX QSOsFollow 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
32W9XT
Learning PropagationGet on the air!
Get on different bands at different timesNCDXF Beacons
http://www.ncdxf.org/beacons.htmlBeacons on 20, 17,15, 12 & 10 meters
Propagation Prediction ProgramsW6ELITS HF Prop
W9XT 33
Learning Propagation (continued)Operating activities that help learn
propagationWork on awards
Worked All States DXCC – work 100 countries
Contests The increased activity gives a good indication of
band openings
W9XT 34
SummaryHF provides a life time of challenges and
funOpens the whole world
35W9XT