Propagation Anomalies

(Propagation prediction is not an exact science - ARRL p.17-184)

Aurora Curtain; Northern Lights, radio auroras, solar wind interaction between earth magnetic field and Sunspots & K-index

Fading: Caused by changing ionosphere, the layer heights or passing planes

Static-crash: SIDs

Back Scatter: Reflected signals into the Skip Zone.

Forward Scatter: Ionospheric scatter - freq. Above MUF, useable

out to 1200mi.

Tropospheric scatter - useable out to 500mi from Skip zone.

Meteor Scatter- last only a few minutes.

MUF - Max Useable Freq.: The highest frequency useable.

FOT – 85% of MUF: Freq. of optimum transmitting, optimum traffic freq.

LUF – Lowest Useable Freq.

Multipath Fading: caused by receiving signal over several paths.

SID - Sudden Ionosphere Disturbances - Solar Flare UV radiation

1. increases ionization of D layer, blocking out HF comms.

2. Using E&F layers on side of earth facing flare, Lasts a few minutes.

Es - Sporadic-E Opening: Caused by winds flowing in opposite

Direction-producing wind shears in E region. May to

August; Dec. to Jan.28 & 50Mhz Bands; 400 to 1300mi.

Solar Activity: (Solar Radiation) Radiation of the ionosphere

Layers. Cycles: Daily - 27 days - Seasonal

Sunspot: Zurich - Increase/Decrease in cycle's approx. 9 to

13-year cycle; maximum ionization occurs at peak of

Cycle, "higher the Sunspot Number the better the comms".

Solar Flux Index/Numbers (SFI): 60 to 70 Poor 20m & up (14MHz)

(2800MHz Daily 1700Z) 90 to 110 Good up to 12m (24MHz)

120 to 200 Good up to 10m (28MHz)

200 to 260 Good to 6 meters

The SFI indications are more descriptive of daily conditions than the Sunspot number. The higher the SFI, the higher the Sunspot number, the stronger the ionosphere becomes, and thus causing a refraction of higher frequencies.

R-index Sunspot number (http://sec.noaa.gov/ftpdir/latest/dayind.txt)

K-index Geomagnetic Aura Solar Disturbance activity

A-Report is averaging of the K-index

K-indicies A-indices Range of Condition

K-index 0 to 2 A-index 0 to 8 Quiet

K-index 0 to 3 A-index 8 to 16 Unsettled

K-index 3 to 4 A-index 16 to 30 Active

K-index 4 to 5 A-index 30 to 50 Minor Storm

K-index 6 or greater A-index 50 to 100 Major Storm

K-index 7 or greater A-index 100&highter Severe storm

Smoothed Sunspot Number - Solar Flux Index - WWV Forcast, Reports

(SSNs) 0 = (SFI) 64 MOD QU/UN

10 = 71 MOD QU/ACTIVE

20 = 79 MOD QT-ACTIVE

60 = 111 MOD QT-Uns

70 = 119 sa: Lo = )mo

90 = 136 gf: Qu-um

100 = 145 RAD Angle: 6

110 = 155 Dist: 5854km

120 = 164 Hops: 2

140 = 183 MUF (90%):16.3

160 = 183 MUF (50%):18.7

180 = 224 MUF (100%): 22.1

190 = 234 HIGH/QUIET-UNSET

200 = 245 LOW-MOD/QUIET-UNSET

NOTE: SSNs = SFI (ARRL p.17-184)

Joe Mettle sends: