1 Technician Licensing Class These Power Point presentations are available to individuals who register with The W5YI Group’s HamInstructor.com program. The presentations are provided by Master Publishing and The W5YI Group and include material that is covered by U.S. and International copyrights. They are intended solely for the use of Registered Instructors using the Gordon West, WB6NOA, Technician Class, General Class, and Extra Class study manuals to teach FCC Amateur Radio Licensing Classes. Registration through HamInstructor.com constitutes a Licensing Agreement between The W5YI Group and the registered instructor under which the instructor agrees not to copy or distribute the Power Point presentations to unauthorized users.

2 Technician Licensing Class Weak Signal Propagation Valid July 1, 2014 Through June 30, 2018

3 3 Amateur Radio Technician Class Element 2 Course Presentation  ELEMENT 2 SUB-ELEMENTS (Groupings) About Ham Radio Call Signs Control Mind the Rules Tech Frequencies Your First Radio Going Solo Repeaters Emergency!  Weak Signal Propagation

4 4 Amateur Radio Technician Class Element 2 Course Presentation  ELEMENT 2 SUB-ELEMENTS (Groupings) Talk to Outer Space! Your Computer Goes Ham Digital! Multi-Mode Radio Excitement Run Some Interference Protection Electrons – Go With the Flow! It’s the Law, per Mr. Ohm! Go Picture These! Antennas Feed Me With Some Good Coax! Safety First!

5 5 Weak Signal Propagation Basically five layers: D, E, F, F1, and F2. Differences in Day-time and Night-time: D and E disappear at night. F1 and F2 combine at night to become just F. Ionosphere Layers

6 6 Weak Signal Propagation T5C07 Electromagnetic waves are RADIO WAVES. A radio wave is composed of both an electric field and a magnetic field at right angles to each other.

7 7 Weak Signal Propagation Observe differences between: 10-meters, 20-meters 40 meters HF bounces off ionosphere. VHF & UHF pass through.

8 8 Weak Signal Propagation Different layers in the Ionosphere and their miles from the earth

9 Weak Signal Propagation T3C10 Let’s get back down to Earth and talk about Technician class privileges on VHF and UHF frequencies. Generally, your signals will travel “line of sight.” Repeaters are usually put way up on buildings and mountain tops to extend line-of-sight range. But if you and a pal could walk on water, and you each started walking in the opposite direction, you would lose sight of each other’s smiling face at about 5 miles due to the curvature of the Earth. Amazing, huh? VHF and UHF radio signals are blocked by the curvature of the Earth, too.

10 Weak Signal Propagation T3C11 Now if you and your pal, walking on water, lost sight of each other’s smiling face at 5 miles because of the curvature of the Earth, you could probably keep yakking on your 2-meter handheld an additional couple of miles, thanks to the refractive index of air on radio signals, which makes the Earth seem less curved. So if you do your line-of-sight calculations, add another 15 percent to your visual range and I bet your radio signals will be heard loud and clear beyond the visual horizon. This additional “mileage” is applied to BOTH of your signals, so the actual “beyond horizon benefit” is about 30%. This is the origin of the common “4/3 Earth” principle for determining VHF distance.

11 Weak Signal Propagation T3C01 The 6- and 10-meter bands are an exception to Technician Class privileges on frequency bands that usually propagate signals that travel line of site. On the 6- and 10-meter bands, during the summer months, signals will many times refract off the E-layer of the ionosphere, and come back down hundreds and thousands of miles away. However, on 2 meters and higher UHF frequencies, signals are usually not refracted by the ionosphere.

12 Weak Signal Propagation T3C05 You and a pal just earned your Technician Class licenses and you each have a new handheld, tuned to a simplex frequency. Your friend lives on the other side of a jagged rocky hill. Will you be able to communicate by simplex (no repeater) over this hill? Likely, yes. VHF FM signals from base stations, handhelds, and mobile radios normally propagate vertical polarization. When the lower edge of the vertical wave strikes a distant, elevated sharp object, like the cliff between you and your friend, the lower portion of the wave tends to drag over the cliff, causing the upper portion of the wave front to bend right down to where your friend is waiting to hear from you. Knife-edge diffraction caused by an intervening building or hill may give you some great communications fun with your new Technician Class amateur radio license!

13 Weak Signal Propagation

14 Weak Signal Propagation T3C06 It is not uncommon to be able to communicate through a repeater several hundred miles away – well beyond line-of-sight. This is because your signal gets caught up in a warm air inversion, located in the troposphere. This longer than usual communications range is called tropospheric scatter, often referred to as tropospheric ducting.

15 Weak Signal Propagation T3C08 Ever see a mirage? This is frequently seen as water shimmering on a roadway, but it is actually the blue sky that you see on an inferior mirage. Another type of mirage may occur above us, called a superior mirage. This allows you to see things suspended upside down, many miles away! The superior mirage also creates longer than usual range on the 2 meter and 70 cm bands, thanks to a temperature inversion when a layer of warm air traps colder air below it creating a tropospheric duct. Tropospheric Ducting

16 Weak Signal Propagation T3C03 VHF signals on the 2 meter band travel “line of sight.” The higher up you are from the surface of the Earth, the better your range. An interesting phenomenon, called an auroral reflection, may influence 2 meter single sideband and FM signals. Six meter and 2 meter radio waves will bounce off an auroral curtain as if they were bounced off a steel building! The incoming signals from a distant station will sound fluttery and distorted. This is the unmistakable sound of an auroral bounce that can be heard hundreds of miles away! Listen to an auroral radio call on the enclosed “On the Air” CD!

17 Weak Signal Propagation T3C07 The Leonids and Geminids meteor showers are fun for hams! As a new Technician Class operator, you can work the entire 6 meter band, running up to 1500 watts of power output. This is plenty of power to bounce a signal off a meteor trail or even the Moon! Hear this on the enclosed “On the Air” CD!

18 Weak Signal Propagation T3A11 It is the ionosphere that gives us propagation all over North America on the 6- and 10-meter bands. We are just beyond the peak of Solar Cycle 24 and ready to go down its backside. Although we won’t see any F2 skip on 6- and 10-meters during our slide down on solar cycle 24, sporadic E occurs every summer at any spot during the cycle for fun 6 and 10 meter skywave DX! Thanks to the ionosphere!

19 Weak Signal Propagation T3C02 The 6-meter band, 50 to 54 MHz, is referred to as The Magic Band. During the summertime, it is full of surprises. Many Technician class operators will buy 6-meter multi-mode equipment and operate upper sideband at MHz. So, one morning you’re on the air chatting with a pal across town, and a voice out of nowhere drops into the conversation and announces that she is located 1,500 miles away. Her signal is coming in via Sporadic-E refractions off of ionized patches of the ionosphere’s E-layer. This is a common occurrence on the 6- and 10-meter bands, during summertime, in the early morning and late afternoon hours.

20 Weak Signal Propagation T3C09 Remember your 10 meter SSB privileges are from to MHz. Start out around and give your best spirited CQ call. Likely, during the day, during times of high Sun spot activity, you may get a response from another station halfway across the country! On 6 meters, try your SSB CQ call on MHz, upper sideband.

21 Weak Signal Propagation T3A09 Elliptically (or circularly) polarized radio signals can be received with either a vertically or horizontally polarized antenna. However, you can obtain significant improvement in reception by using a circularly polarized antenna that is properly matched to the sense of the incoming signal; that is, using a right-hand circularly polarized antenna to receive a right-hand circularly polarized signal. Conversely, if you use a circularly polarized antenna of the wrong sense, the signal can often be totally rejected. This phenomenon lends itself to a lot of exciting experimentation, since very few hams currently take advantage of circularly polarized antennas on H.F. These two “senses” are officially known in the scientific community as the X and the O modes, for extraordinary and ordinary rays, respectively. (Nobody said physicists could spell!)

22 Weak Signal Propagation T3C04 Regularly on 10 meters we may communicate via skywaves with stations close to 1,000 miles away, thanks to sporadic E skip. On 6 meters, this phenomenon usually occurs several times a week during the summertime and in December. On 2 meters, skip conditions may prevail once or twice a month, just for a few minutes, during the summertime.

23 Weak Signal Propagation T3C12 Easy, super-long-distance HF propagation is possible at the peak of the Sunspot cycle, when the F2 ionospheric layer is thick and stable. Just a few watts can gain you world-wide communications on 6 and 10 meters during these times. However, as the solar activity declines through its cycle, it generally starts “dying” from the top end down, as the higher frequencies become progressively less usable. But all is not lost as there are other, intriguing things happening besides the “normal” F2 propagation. Sporadic E can provide low-loss communications on 6 and 10 meters at any time during the solar cycle. However, they don’t call it “sporadic” for nothing! It’s important to be listening to catch these rather fleeting episodes. More reason to spend more time on the air!

24 Weak Signal Propagation T3B02 Although the magnetic and electric fields of a radio wave are always at right angles to one another, by convention the polarization of a radio signal is defined by its electric field. It is easy to remember this because the E field is the same orientation as the antenna ELEMENT that creates it. Horizontal wires have horizontal electric fields. Vertical wires have vertical electric fields.

25 Weak Signal Propagation T3A08 With exciting voice privileges on both 6 meters and 10 meters via ionospheric skip, Technician Class operators can work the world! Propagation on HF is different from what you will experience on a VHF handheld radio. Most long distance radio paths are through the ionosphere and can take long, circuitous routes from Point A to Point B, sometimes several paths at the same time! As these signals refract via skywaves, they will constantly build up and then recede, like ocean waves coming in to shore. (As fate would have it, the other operator says his name and location just as the signal takes a brief nose dive!) This constant coming and going of the skywave signal is due to selective fading where the incoming signal may arrive from several paths, combining in phase to be nice and strong, yet taking a quick deep fade as the signal comes in from different paths, out of phase. The good news with all this building and declining of signal strength from overseas skywave stations is that the fade outs are quick in duration, leading to nice longer 10 seconds of solid reception. This in and out is also a good sign to you that the band is open for long range (DX) skywave contacts!

26 Weak Signal Propagation Element 2 Technician Class Question Pool Valid July 1, 2014 Through June 30, 2018

27 T5C07 What is a usual name for electromagnetic waves that travel through space? A.Gravity waves B.Sound waves C.Radio waves D.Pressure waves

28 T3C10 What is the radio horizon? A.The distance over which two stations can communicate by direct path B.The distance from the ground to a horizontally mounted antenna C.The farthest point you can see when standing at the base of your antenna tower D.The shortest distance between two points on the Earth's surface

29 T3C11 Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations? A.Radio signals move somewhat faster than the speed of light B.Radio waves are not blocked by dust particles C.The Earth seems less curved to radio waves than to light D.Radio waves are blocked by dust particles

30 T3C01 Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area? A.They are too weak to go very far B.FCC regulations prohibit them from going more than 50 miles C.UHF signals are usually not reflected by the ionosphere D.They collide with trees and shrubbery and fade out

31 T3C05 Which of the following might cause radio signals to be heard despite obstructions between the transmitting and receiving stations? A.knife-edge diffraction B.Faraday rotation C.Quantum tunneling D.Doppler shift

32 T3C06 What mode is responsible for allowing over-the- horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis? A.Tropospheric scatter B.D layer refraction C.F2 layer refraction D.Faraday rotation

33 T3C08 What causes tropospheric ducting? A.Discharges of lightning during electrical storms B.Sunspots and solar flares C.Updrafts from hurricanes and tornadoes D.Temperature inversions in the atmosphere

34 T3C03 What is a characteristic of VHF signals received via auroral reflection? A.Signals from distances of 10,000 or more miles are common B.The signals exhibit rapid fluctuations of strength and often sound distorted C.These types of signals occur only during winter nighttime hours D.These types of signals are generally strongest when your antenna is aimed west

35 T3C07 What band is best suited to communicating via meteor scatter? A.10 meters B.6 meters C.2 meters D.70 cm

36 T3A11 Which part of the atmosphere enables the propagation of radio signals around the world? A.The stratosphere B.The troposphere C.The ionosphere D.The magnetosphere

37 T3C02 Which of the following might be happening when VHF signals are being received from long distances? A.Signals are being reflected from outer space B.Signals are arriving by sub-surface ducting C.Signals are being reflected by lightning storms in your area D.Signals are being refracted from a sporadic E layer

38 T3C09 What is generally the best time for long-distance 10 meter band propagation via the F layer? A.From dawn to shortly after sunset during periods of high sunspot activity B.From shortly after sunset to dawn during periods of high sunspot activity C.From dawn to shortly after sunset during periods of low sunspot activity D.From shortly after sunset to dawn during periods of low sunspot activity

39 T3A09 Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized? A.Digital modes are unusable B.Either vertically or horizontally polarized antennas may be used for transmission or reception C.FM voice is unusable D.Both the transmitting and receiving antennas must be of the same polarization

40 T3C04 Which of the following propagation types is most commonly associated with occasional strong over- the-horizon signals on the 10, 6, and 2 meter bands? A.Backscatter B.Sporadic E C.D layer absorption D.Gray-line propagation

41 T3C12 Which of the following bands may provide long distance communications during the peak of the sunspot cycle ? A.Six or ten meters B.23 centimeters C.70 centimeters or 1.25 meters D.All of these choices are correct

42 T3B02 What property of a radio wave is used to describe its polarization? A.The orientation of the electric field B.The orientation of the magnetic field C.The ratio of the energy in the magnetic field to the energy in the electric field D.The ratio of the velocity to the wavelength

43 T3A08 Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection? A.Frequency shift due to Faraday rotation B.Interference from thunderstorms C.Random combining of signals arriving via different path lengths D.Intermodulation distortion