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