radio wave propagation - k9vick9vic.info/files/classes/amateur extra propagation final 2013.pdfradio...

Radio Wave Propagation

Teach you enough to get all the propagation questions

right during the VE Session

Learn a few things from you about your experiences

Have fun

Finish everything on time (if not a little early)

Bob, KA9BH

Eric, K9VIC


Teach you enough to get all the propagation questions

Learn a few things from you about your experiences

Finish everything on time (if not a little early)


But first some leftovers from last week...


But first some leftovers from last week...

The Smith Chart

Dr. Zachary Smith

The Smith Chart

Dr. Zachary Smith

The Smith Chart Resistance/conductance component at the

center.

Zero resistance at left

Infinite resistance at right

Reactance arcs above/below the center.

Inductive above (+1j

Capacitive below (

Standard (normalized) resistance at center of the chart.

SWR circles around center.

The Smith ChartResistance/conductance component at the

Zero resistance at left

Infinite resistance at right

Reactance arcs above/below the center.

Inductive above (+1j Ω at top center)

Capacitive below (-1j Ω at bottom center)

Standard (normalized) resistance at center of

SWR circles around center.

The Smith Chart What's it good for?

Used to portray complex impedances graphically

Can be used to solve for impedances when transformed through feedlines, etc.

Move clockwise around the chart from a load to the source

One wavelength is twice around the chart (e.g., ¼ wavelength would be ½ way around the circle)

Can be used for the open/shorted feedline questions.

The Smith Chart

Used to portray complex impedances

Can be used to solve for impedances when transformed through feedlines, etc.

Move clockwise around the chart from a load to

One wavelength is twice around the chart (e.g., ¼ wavelength would be ½ way around the

Can be used for the open/shorted feedline

The Smith Chart Open/Shorted Feedline Questions:

Shorted feedline, 1/8 wavelength long A shorted feedline (at the load) has essentially

zero resistance

Moving ¼ turn clockwise (toward the source) we arive at +1j from the source.

Open feedline, 1/4 wavelength long An open feedline (at the load) has essentially

an infinite resistance

Moving 1/2 turn clockwise (toward the source) we arive at zero viewed from the source.

The Smith ChartOpen/Shorted Feedline Questions:

Shorted feedline, 1/8 wavelength longA shorted feedline (at the load) has essentially zero resistance

Moving ¼ turn clockwise (toward the source) we arive at +1j Ω, an inductive load viewed from the source.

Open feedline, 1/4 wavelength longAn open feedline (at the load) has essentially an infinite resistance

Moving 1/2 turn clockwise (toward the source) we arive at zero Ω, a low impedance load viewed from the source.

VE Exam Three Exam questions, one each from

three groups:

Earth-Moon-Earth (EME) communications; meteor scatter.

Transequetorial propagation; long path; gray line; multi-

Aural propagation; selective fading; radio-path horizon; takeflat or sloping terrain(covered last session); earth effects on propagation (also covered last session); less common propagation modes.

VE ExamThree Exam questions, one each from

Earth (EME) communications; meteor scatter.

Transequetorial propagation; long path; -path propagation.

Aural propagation; selective fading; path horizon; take-off angle over

flat or sloping terrain(covered last session); earth effects on propagation (also covered last session); less common propagation modes.

HF Propagation

Ground Wave (160 –

50 miles maximum

Polarization dependent

Vertical better than horizontal Remember most horizontal

antennas have a small vertical componant (next slide)

Frequency dependent

Lower Frequency better than higher

Due to refraction along the earth's surface

HF Propagation

– 10 meters)

50 miles maximum

Polarization dependent

Vertical better than horizontalRemember most horizontal antennas have a small vertical componant (next slide)

Frequency dependent

Lower Frequency better than higher

Due to refraction along the earth's

HF Propagation Ground Wave

HF Propagation

HF PropagationIonosphere



Critical Frequency

The highest frequency that will be returned to the earth when transmitted vertically under given ionospheric conditions

Critical Angle

The highest angle with respect to a vertical line at which a radio wave of a specified frequency can be propagated and still returned to the earth from the ionosphere


The highest frequency that will be returned to the earth when transmitted vertically under given ionospheric

The highest angle with respect to a vertical line at which a radio wave of a specified frequency can be propagated and still returned to the earth from the


Maximum Usable Frequency (MUF)

The upper frequency limit that canbe used for transmissions betweentwo points independent oftransmitter power.


Maximum Usable Frequency (MUF)

The upper frequency limit that canbe used for transmissions betweentwo points independent oftransmitter power.


Ionospheric Layer and Height(miles)

D Layer 30 - 60

E Layer 60 - 90

F1 Layer 140

F2 Layer 160 - 200

F Layer 160 - 200


Ionospheric Layer and Height Maximum Skip Distance(miles)

Absorbtive

1,400

Minimal Skip Affect

2,500

2,500


Long Path

Signal takes the longer of two great circle paths

Long path is 180

May hear both paths (echo)

Works on all HF bands (160 thru 10meters)

Very consistent on 20


Signal takes the longer of two great

Long path is 180° opposite short path

May hear both paths (echo)

Works on all HF bands (160 thru 10-

Very consistent on 20-meters


Sporadic E

Applies to VHF (or 10

50 MHz: 6000+ miles 144 MHz: 1900 miles

Strong cycle May, June, July

Lesser cycle December, early January

Independent of Solar Cycle


Applies to VHF (or 10-meters)

50 MHz: 6000+ miles144 MHz: 1900 miles

Strong cycle May, June, July

Lesser cycle December, early January

Independent of Solar Cycle


Sporadic E

When 28 MHz goes short (250 miles), 50 MHz goes long (1,400 miles)

When 50 MHz shortens (400 miles), 144 MHz goes long (1,400 miles)

HF may seem dead as the Fblocked (or the Ereflector)

Not the same as a Pedersen Ray (Fphenomina)


When 28 MHz goes short (250 – 300 miles), 50 MHz goes long (1,400 miles)

When 50 MHz shortens (400 miles), 144 MHz goes long (1,400 miles)

HF may seem dead as the F-layers are blocked (or the E-layer is the top

Not the same as a Pedersen Ray (F2

HF PropagationNVIS (Near Vertial Incident Skywave)

HF PropagationNVIS (Near Vertial Incident Skywave)

HF PropagationIonosphere (backscatter)HF PropagationIonosphere (backscatter)


Grayline Propagation

Occurs at daytime/nighttime terminator (twilight, sunset, sunrise)

D-layer quickly disappears or hasn't yet formed

F-layer is present

Skip is 8-10,000 miles on 3 or 4 HF bands

Always along Grayline (NOT one station in twilight, the other in darkness or light)


Grayline Propagation

Occurs at daytime/nighttime terminator (twilight, sunset, sunrise)

layer quickly disappears or hasn't yet

layer is present

10,000 miles on 3 or 4 HF

Always along Grayline (NOT one station in twilight, the other in darkness or light)

HF Propagation Trans-equatorial propagation

Best late afternoon/early evening

Reflection height suggests bulged Flayer

3100 -5000 miles over magnetic equator

(add frequencies) Why do we care?

Chicago to magnetic equator is more than 2500 miles (south of 'real' equator)Might work from TX or FL

HF Propagationequatorial propagation

Best late afternoon/early evening

Reflection height suggests bulged F-

5000 miles over magnetic

(add frequencies)Why do we care?

Chicago to magnetic equator is more than 2500 miles (south of 'real' equator)Might work from TX or FL

HF Propagation Selective Fading

Phase difference between components of a signal combine and cancel (generally due to multipath)

Large bandwidth are more effected

Phase band modes (even narrow band) are very succeptible

HF Propagation

Phase difference between components of a signal combine and cancel (generally due to multipath)

Large bandwidth are more effected

Phase band modes (even narrow band) are very succeptible

PropagationIonosphere

Meteor Scatter

Transmit using 15 second intervals

Popular modes:

Fast CW (100+ WPM)

WSJT

JT6

Best during meteor showers, and in the morning (heading into the shower)

Can be used any time with JT

PropagationIonosphere

Transmit using 15 second intervals

Fast CW (100+ WPM)

Best during meteor showers, and in the morning (heading into the shower)

Can be used any time with JT-modes

EME

Earth-Moon-Earth

Theoretically works for any two stations that can both see the moon (12,000 miles)

Frequencies Used:

144.000 - 144.100

432.000 - 432.100

Transmit 'schedule'

2-meters: 2 minutes on, 2 minutes listening

70-cm: 2.5 minutes on, 2.5 minutes listening

EME

Theoretically works for any two stations that can both see the moon (12,000 miles)

144.100

432.100

meters: 2 minutes on, 2 minutes listening

cm: 2.5 minutes on, 2.5 minutes listening

EME

Considerations Distance (2-week cycle)

Perigee (closest to earth) = 359,000 km

Apogee (farthest from earth) = 404,510 km

Why do we care, they're both pretty far?

Apogee is about 1.127 X perigee

Signal increase is (1.127)(~30%)

DB = 10 log 1.3/1

= 1.14 dB

EME

week cycle)

Perigee (closest to earth) = 359,000 km

Apogee (farthest from earth) = 404,510

Why do we care, they're both pretty far?

Apogee is about 1.127 X perigee

Signal increase is (1.127)2=1.270

DB = 10 log 1.3/1

EME

Considerations

Moon's orbit is eliptical and tilted re: earth

Velocity not constant relative to earth

Allows 59% of the moon to be seen

41% of the far side (not dark) never seen

Libration Fading

Fluttery, irregular fading

EME

Moon's orbit is eliptical and tilted re:

Velocity not constant relative to

Allows 59% of the moon to be seen

41% of the far side (not dark) never

Libration Fading

Fluttery, irregular fading

EME Considerations

How do we increase s+n/n?

Bandwidth (cw, WSJT, JT65, etc.) ERP (amps, lots of aluminum)

Rx noise level (low noise rx a must)

EME

How do we increase s+n/n?

Bandwidth (cw, WSJT, JT65, etc.)ERP (amps, lots of aluminum)

Rx noise level (low noise rx a must)

VHF/UHFPropagation Troposhperic Ducting

Troposphere 0

Ducting products potential contacts of 500 miles

Due to radio horizon

Horizon =(2h)

Radio horizon ~15% farther than geometric horizon

Six miles = 31,680 feet, Horizon = 251.7 miles (double for two stations)

VHF/UHFPropagationTroposhperic Ducting

Troposphere 0 – 6 miles in height

Ducting products potential contacts of

Due to radio horizon

Horizon =(2h)1/2 h = haathorizon in miles

Radio horizon ~15% farther than geometric horizon

Six miles = 31,680 feet, Horizon = 251.7 miles (double for two stations)

VHF/UHF Propagation Aural Propagation

Think Aurora Borealis (Australis)

Charged particle from the sun create ions

E-layer ionization layer

SSB rarely readable

CW best option (with fluttery tones)

Both stations point antennas north (in the northern hemisphere)

VHF/UHF Propagation

Think Aurora Borealis (Australis)

Charged particle from the sun create

layer ionization layer

SSB rarely readable

CW best option (with fluttery tones)

Both stations point antennas north (in the northern hemisphere)

VHF/UHF Propagation

Meteor Scatter

Meteor creates 12height

Propagation 500 –

Works on 28 to 144 MHz (50 MHz best bet)

Short lived:

30 seconds on 50 MHz


<1 second on 432 MHz

VHF/UHF Propagation

Meteor creates 12-mile ion trail at E-layer

– 1400 miles

Works on 28 to 144 MHz (50 MHz best bet)



<1 second on 432 MHz

Radio Wave Propagation Questions?


radio wave propagation - k9vick9vic.info/files/classes/amateur extra propagation final 2013.pdfradio...

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