sources and the work of the original image makers is acknowledged) What Are Radio Waves And How Do We Use Them (Pictures and Images in these slides were collected from a variety of internet sources and the work of the original image makers is acknowledged)

Comments About Presentations When I give the answer to a test question it is in red – BUT! The best way to study for your test is to read the question pool and highlight and read only the right answer The purpose of these slide presentations is to give you the big picture – help you know what terms mean – and help you to understand why certain answers are correct Don’t be trying to memorize test question answers from the presentation!

Energy Moves Through Space as Electromagnetic Waves Like Ripples on a Pond only these are Electromagnetic Waves What kind of wave carries radio signals Between transmitting and receiving Stations? Electromagnetic (T3A-07) They move at the speed of light (T3B-04) (300,000,000 meters per second) (T3B-11) Ie 7.5 laps around the earth in a second

Why Do We Call These Waves Electromagnetic? Because they have 2 parts Radio waves have an electric Field And a Magnetic Field (T3B-03) You have an electric field moving up and down and a magnetic field moving side to side so they are a lot cooler than waves in a pond.

So Why Does it have to be the Electric Field that Moves Up and Down? It doesn’t have to be that way Electromagnetic waves are Polarized – they are different when laying down than when standing up. The electric field determines which way they are polarized. (T3B-02) If the electrical field is going up and down we are Vertically Polarized If the electrical field is side to side then we are Horizontally Polarized. You are probably familiar with Polarized sun glasses that admit light only from specific directions.

More About Wave Characteristics The distance a wave travels during one cycle is called the Wavelength (T3B-01) One Cycle The height of a wave is called Its Amplitude Big waves have more energy than little waves.

Wavelength determines how many cycles the wave can go through in a second If it has a short wavelength it goes up and down a lot and is said to have a high frequency. If it has a long wavelength it goes up and down less often and is said to have a lower frequency As the wavelength gets shorter the frequency increases. (T3B-05) If I have a piece of string and I cut it into short pieces I will have more pieces than if I cut it into long pieces.

Wavelength is how we tell what kind of Electromagnetic Energy it is. Radio waves are At least ½ cm (1/6th of An inch) long. Your radio communication signal They carry radio and TV signals Our cell phone signal Radar And we microwave Our food with them Shorter wavelengths are the light we see Or the X rays that doctors use to look inside us.

Looking at Radio Spectrum Radio waves for AM broadcast are over 100m long (around 2 foot ball field long) Radio waves for FM broadcast are over 3 m long (around 10 feet) Radio waves for your cell phone or TV are around a foot long

Another Way of Describing a Part of the Spectrum is Frequency You can determine what kind of radio waves you are using either by its Wavelength or its frequency (number of times it goes up and down or cycles in one second). Frequency is a big number – a 10 meter wavelength cycles 30,000,000 times a second – we say Megahertz.

Radio Waves that Will be Important to you when you get your license Very High Frequency (VHF) – from about 10 meters to 1 meter We also describe it by how many cycles it can make in one second VHF is 30 Megahertz to 300 Megahertz (T3B-08).

Another Important Frequency Ultra High Frequency (UHF) goes from 300 megahertz to 3 gigahertz (T3B-09) (giga means billion)

For Amateur Radio Operators Wanting to Talk Around the World High Frequency (HF) goes from 3 megahertz to 30 megahertz (T3B-10)

We Can Describe Which Part of the Radio Spectrum we are talking about by either frequency or wavelength Since wavelength and frequency are related you must be able to convert back and forth. (T3B-06)

Lets Demonstrate 300/ 30 MHz = 10 meters 300/frequency = wavelength (T3B-06) By George I do believe it works

By Using Only Certain Wavelengths or Frequencies we can keep our signals separate so we don’t all pile up on top of everyone else In the US the Federal Communications Commission (FCC) divides up who gets to use what frequencies. Almost everything requires some type of license.

So What Will A Ham Radio License Let You Use Notice that the Property we are Using to identify Different “bands” We are allowed To use is Wavelength. (T3B-07) Very important For our local Communication 2 Meters And 70 centimeter (centi – means 1/100th so 70 centimeters is 0.7 meters)

Technician Bands 6 meters is 50 to 54 MHz 2 meters is 144 to 148 MHz (but you will need a separate radio for this band) 2 meters is 144 to 148 MHz (most of our radios are designed for this frequency) 1.25 meters is 222 to 225 MHz (you will need a special radio for this or a specific type of Baofeng radio) 70 cm is 420 to 450 MHz (if you buy a Baofeng radio it also does this frequency)

A Side Note on 70 cm (One of the Baofeng Radio bands) Amateur operators have what is called a secondary allocation there. This means that if the primary user (US Military) is using the frequency you must stop your talking and let them use it. (This only really effects people near a few East Coast military bases)

Questions they may ask You could memorize the answers (T1B-03)

Or You Can Make Use of Your 300 formula you already learned (T1B-03) 300/ 6 = 50 MHz you know immediately it’s A or B (with a little memory you know 6 meters is the lower end of the band so it has To be B)

Try Again (T1B-04) 300 / 146.52 = just less than 2 pick A (yes you can bring a calculator to the test) (T1B-05) 300 / 0.7 = 429 - only C is even close

Finishing Off the Last of These Questions 300 / 0.23 = 1304 only B is even close 300 / 223.5 = 1.34 only D is even close

Interesting but Why Do Amateur Radio Operators have frequencies spread all over the map? There are 24 different Bands on that chart! Why would Amateur Operators want their authorized frequencies scattered?

Different Frequencies Behave Differently – more options means more chances to get the message through VHF and UHF frequencies that Technicians use operate Line Of sight. That means the radio antennas have to have an open straight line between them. Nice things radio waves are better than eye balls – I can’t see 50 miles but a 2 meter radio wave can travel that far.

So That Means 2 meter Radios are Good for 50 miles? Well – maybe not The earth is curved. Depending on how high the antenna’s are sooner or later the earth will get in the way. The distance two stations can Communicate directly by line of sight is the radio horizon. (T3C-10) Great Dedication – but is it practical? For people on the ground holding a radio at face height you have about 6 miles before the earth will block you.

Ok But I Can Still Do a Lot With 6 miles Except that the earth isn’t Perfectly curved either. Stuff can get in the way. Sometimes if you are driving Along listening or talking On the radio the signal will Become strong and then Suddenly weak. This is called Picket Fencing (T3A-06) If your radio signal was good And then suddenly its weak Try moving a few feet one Way or the other. (T3A-01)

If I Have Stuff in the Way Will it Always Block My Signal? Why are UHF signals often More effective than VHF Signals inside buildings? The shorter wavelength allows Them to more easily penetrate The structure of buildings. (T3A-02) Nothing is going to drill through a mountain But! Higher frequency bands will drill through Buildings – particularly if you want to talk To someone inside. Drill through 6 meters - poor 2 meters – marginal 70 cm - not bad 33 cm – pretty good (so we are starting to see why having multiple frequency bands is useful)

Are There Ways Around Obstructions besides moving or drilling through? An obstruction can bend radio waves And send waves into places we shouldn’t Be able to hit. Knife Edge diffraction can cause a Signal to be heard even when there is An obstruction in the way. (T3C-05) Knife edge diffraction works Better for long wave lengths 70 cm doubtful 1.25 meters good 2 meters better 6 meters best The Pam Flemming Case.

Ok If Nothings In the Way I Can Get 6 miles – right? That depends on whether something eats up the power in your signal. Atmospheric moisture eats radio energy for lunch! Short radio antennas are compact and nice, but they have a lot of electronics to fool the radio wave into thinking the antenna is longer. These electronics eat-up your transmission power Its called loading an antenna – you insert An inductor – (wire coil) into the antenna To make it electrically longer (T9A-14)

Beating the Eating I Love Eating 33 cm And 70 cm Wavelengths! (These wavelengths have big problems with atmospheric moisture) 1.25 meter and 2 meter wavelengths are good for light eating. 6 meters for lunch? Please tell me your kidding Atmospheric Humidity

So What About the Lousy Antennas Whats inside a rubber Duck antenna (Coil structures eat Power) Rubber Ducky Not the One he won’t help you have some fun. A rubber duck antenna does not receive or transmit as effectively as a full size antenna. (T9A-04) To really mess-up use a handheld radio in a car – the metal shell of your car intercepts signals. The signal from inside your car is much weaker than outside (T9A-07) (like about 1/10th as strong – Tithing is a true principle but not when it comes To radio signals)

A Baofeng (and most handheld radios from other manufactures) comes with a rubber duck antenna This is a rubber duck antenna. By the time it wastes a good part of your radios power you will only get about 2.5 to 3 miles (talking to another person on the ground). You can buy a different antenna for less than $10

Ok So What is a Full Size Antenna? Just like the length of a string determines the sound it makes naturally (resonate) so to the length of the antenna determines what wavelength of radio wave it sends out naturally. Most VHF and UHF voice Communication uses an Antenna is a simple straight Up and down wire. A vertical antenna will produce a vertically Polarized radio wave with the Electrical field perpendicular to the earth (T9A-02) The antenna should be 1/4th the wavelength – good ½ the wavelength – better So a quarter wave 2 meter antenna is 1/4th of the wavelength or about 19 Inches (T9A-08) A half wave 6 meter antenna is About 112 inches long. (T9A-09) (That’s just shy of 10 feet long – wouldn’t that be Fun to put on top of your car)

Full Size Antenna Size Leads to Some Practical Considerations 112 inches for ½ wave 6 meter antenna (T9A-09) 49 inches for A 5/8th wave 2 meter antenna About 17 Inches for a 70 cm ½ wave antenna Still nearly 5 ft for a ¼ wave 6 meter antenna We can probably live with that The 70 cm band is the only one where a full size handheld Antenna is really practical. For 4 to 5 mile local communication With a handheld radio 70 cm may actually work better than 2 meters.

Ok – If I have a good antenna and nothing in the way can I get 6 miles? Maybe not. What’s wrong with these Pictures?

What Direction are most Antennas for VHF and UHF transmissions Oriented? That’s right - Vertical That means the radio waves will be Vertically polarized with the electric field going Up and down and the magnetic side to side

Which way is this antenna pointing So the radio waves will be Horizontally Polarized with the electrical field going side to side and the magnetic up and down Yipes – Stripes its almost Horizontal! What can happen when antennas at Opposite ends of a VHF or UHF radio Link are not using the same polarization? The signals will be significantly weaker (T3A-04) (could be as bad as 50 times weaker)

So If I Use a Full Size Antenna on my handheld radio I point the antenna up and there is nothing in the way I can get 6 miles- right? 17 inch ½ wave On 70 cm 19 inch ¼ wave On 2 meters Well – maybe not. Handheld radios only have 3 to 5 watts of power (A light bulb is 75 watts) so the signal may not be strong enough in the right direction to beat the atmosphere eating up your small amplitude radio waves. (Our tests show about 4 to 5 mile maximum with Handheld And a full size antenna)

The Antenna Also Determines the Shape and Direction the radio waves go in If your not aiming at the Target – you might not Hit it.

Concepts of Gain and Take-Off Angle We start out thinking about a “Isotropic Radiator” that puts out electromagnetic waves equally in all directions. The sun is one of our best examples.

Isotropic Radiators Make Poor Antennas And I don’t think this is Part of my emergency Communication plan. I’m on the ground

Antenna Gain Gain is the increase in signal strength in a specified direction Compared to a reference antenna. (T9A-11) If I can aim more of my radio wave energy out across the ground I can Get my signals further before the atmosphere eats them. 1/4th Wave Antenna Radiation Pattern Direction of strongest signal is the Take-off angle (Keeping it low toward the ground is a good thing) Note that the ground is actually part of the antenna in shaping radio wave aim

So What Can I Do With Take-Off Angle? The take-off angle of a Half wave antenna is closer To the ground than a Quarter wave ¼ wave antenna - good (but it’s take-off angle is around 27 degrees) ½ wave antenna – better (lower take-off angle) 5/8th wave antenna – best (lowest take-off angle – around 16 degrees) So why use a properly mounted 5/8th wave antenna for VHF and UHF? Because it offers a lower angle of radiation and more gain than a 1/4th wave (T9A-12) This is why you may actually get better range on a handheld radio using a 17 inch 1/2 wave antenna on the 70 cm band than using a 19 inch ¼ wave antenna on 2 meters.

I Have Another Idea Take-off angle Even though I’m getting more of my Energy down on the ground I’m Still putting the energy out in a 360 Degree circle What if the person I want to talk to is only in one direction?

What If I Could Aim My Radio waves in just one direction across the ground? It turns out you can using A beam antenna A beam antenna is an antenna that concentrates signals in one direction. (T9A-01)

So What Does This Magic Antenna Look Like? The Yagi Antenna (Some of you old enough to remember old TV Antennas outside your home think this looks familiar. That’s because old TV antennas were Yagis) The Quad Antenna The dish antenna (Some of you are thinking about the satellite dish on your house) So what type of antenna are a quad, yagi, and Dish? Directional Antennas (T9A-06)

There is one not so little problem with directional antennas They are not so little! Its hard for them to be practical for most mobile Communication Except maybe Fox-Hunting

But I Want My Full 6 miles And your still giving me only 4 or 5 with my handheld radio Fact of life 1 – a little under 20 inches is about the Maximum practical antenna length for a handheld Fact of life 2 – 70 cm is the only radio band where You can get a ½ wave or 5/8th wave antenna that Gets good gain and aims the signal near the Ground and still be less than 20 inches. Fact of life 3 – the atmosphere loves to eat 70 cm wavelengths and a handheld starts out with only 4 or 5 watts of power.

Try This 49 inch 5/8th wave 2 meter Magmount antenna Put a magmount antenna on the Car Run the connecting cable through The window or around the edge of The door Hook your handheld radio up to the External antenna with the magmount Connecting cable. You think this is the roof of your car but the Antenna thinks it’s the nicest ground plane In town. Why are VHF and UHF mobile Antennas mounted in the center Of the roof? A roof mount antenna provides the most Uniform radiation pattern. (T9A-13) This set up will get you 7 or 8 Miles of range

Wait A Minute – Back Up I thought you said for antennas at head level the earth would get in the way after 6 miles Radio waves will bend just a little so the radio horizon is further away than the Optical horizon for light – that’s how I got my extra mile or two. Why do UHF and VHF radio waves travel further than the visual line of sight? The earth seams less curves to radio waves than light. (T3C-11) The longer the wave length – the better the bending 70 cm - I don’t think so 2 meters – good 6 meters – Better (except a 10 foot antenna on your car is impractical) 10 meters – Best (except a nearly 20 foot antenna on a car is not going to happen)

But a 6 or even 8 mile range will not cover Carbondale Ward We are not even letting Carbondale and Murphysboro Talk! Range with car top 5/8th wave 2 meter Range with ½ wave On 70 cm Range of Handheld With Rubber Duck I don’t think it is practical to extend ranges this way.

So how do I beat a 6 mile limit? Great Spot to Put an Antenna where no one will see What's in Your Attic? The home base station – Not very portable but it gets the antenna in the air.

Height and the Radio Horizon Base Station to Base Station Range Of course to get this range the radios still have to have enough power to beat atmospheric signal eating and have no obstructions. Base Station to Mobile Radio Obviously a network of Base Stations Can talk across Carbondale Ward

Jacking Up the Power A Bit This power is enough to push a signal out About 20 to 30 miles (if there no obstructions And your antenna is on a high enough spot) Power Amplifier Handheld

Of Course You Can Use a Real Mobile Radio You have to Direct connect power To the battery (That means going Through the firewall under The dash and across the Engine compartment) Has as much Power as a Home Base Station.

Then There is How Do We Talk Across the Stake Base to Base Range

Idea – How About Relaying Messages What would be really cool is if we could do it automatically So far we have talked about direct Radio to Radio communication with both radios set to the same frequency. This is called Simplex communication (T2B-01) Next we will consider a repeater that takes a radio signal and automatically repeats it back.

Repeaters Get Around Objects and Extend Range Repeaters can resend your message with MORE POWER than your little handheld has. There are options for putting repeater antennas at higher places Than most of us have access to. (This is the Carbondale Illinois Repeater Location) A handheld radio can normally reach Repeaters 15 to 20 miles away.

Of Course Even a Repeater be Obstructed. Now What? Objects that Block radio waves Also reflect them. Shift around and look for a reflected path.

Remember Too That Object Edges bend and Refract Waves Obstruction

But How Can It Listen and Resend the Message on the Same Frequency without tripping over itself? Well actually – It Can’t Repeaters use one frequency to receive Signals and another to send them We call this Duplex Communication. Example – the Alto Pass Repeater sends Out signals at 146.86 MHz But it receives signals on 146.26 MHz The most common offset on 2 meter repeaters is plus or minus 600 KHz (T2A-01)

More on Repeater Offsets The Carbondale 70 cm repeater sends out Signals at 442.025 MHz But it receives signals on 447.025 MHz The most common repeater offset on 70 cm Is 5 MHz (T2A-03) Notice that the Carbondale 70 cm repeater receives at a higher frequency than It sends – called a positive offset. The Alto pass receives at a lower frequency than What it sends on – called a negative offset. Send on 146.85 MHz Receives on 146.25 MHz

A Repeater Test Question

To Use a Repeater You Must Set Your Radio to Listen on the Repeater Output and Send on the Repeater Input Fortunately most radios have a duplex setting that automatically knows which way and how much to offset. Set the repeaters send frequency and the radio takes care of what you need to do to send to the repeater. (On cheap Chinese Baofeng (Pofeng) radios there is U.S. programming software that will take care of the problem automatically) Great – I get the feeling its telling me a repeater might not work for me even If I have got my radio set to duplex with the proper offsets. (Now what’s all that letter gibberish that sounds like a government agency)

So What is a CTCSS Tone for Access? We’ve all heard of dog whistles that dogs can hear but people can’t. CTCSS stands for Continuous Tone Coded Squelch System. You can set you radio to put out a hum that people can’t hear but a repeater can. It tells the repeater when you want your message repeated. If you don’t send the tone it means don’t repeat this message. Radio operators call them PL tones (Do you want to say Continuous Tone Coded Squelch System when PL tone will do?) DCS is digital code Squelch – it’s a sub audible Telegram message sent Over and over again. (seldom used on amateur Repeaters) A tone burst is a sequence of tones that have to be sent to a repeater to have your message repeated. (Common in Europe)

So What Could the Test Ask? Note this question is not describing a digital sequence being sent or a burst of tones. It is asking about a constant tone - the PL tone or CTCSS pick D

So if Repeaters are so cool when would we consider communicating simplex instead of a using a repeater? The official FCC answer When the stations can communicate directly without using a repeater (T2B-12) A few thoughts for emergency response 1- only a few of our area repeaters have back-up power so the repeater will stop working if there is a power failure. (If regular telephones are out there is a very good chance the power is out too). 2- only one semi-nearby repeater in Puducah Kentucky has enough back-up power to last more than a few days. 3- repeaters are listening frequencies for a lot of people (including bad guys). You may not want to tell the world that so and so is alone with her kids because her husband is dead or injured. (Find a frequency were people are less likely to listen – speaking in code on amateur radio is illegal – it turns out most scanners can’t listen to 1.25 meters)

At the End of the Day there are limits to what we can do with line of sight signals Time to start thinking about whether some of those other bands have an alternative to line of sight propagation

HF has a different Propagation Mode Its called a sky wave – the radio wave goes up into the air – hits an ionized layer in the upper atmosphere called the ionosphere and Is reflected back down to earth. The stations communicating are far From the line of sight of each other. The amount of ionization varies from day to night, season to season, and Year to year due to the sunspot cycle. What part of the atmosphere enables propagation of radio signals around the World? The ionosphere. (T3A-11)

Whether a Radio Wave Reflects Back Depends on its Frequency and the angle it hits at Lower frequencies will reflect back to earth at more angles than higher frequencies At some point the frequency is so high that it will just pass right out into space. This upper limit is called the Maximum usable frequency (MUF).

Of Course Things Can Bounce In Many Frustrating Ways

Another Effect of Bouncing Around Vertically Polarized The signal polarization gets Scrambled. Horizontally Polarized (elliptical refers to be polarized in all different directions) Result (T3A-09)

What Kind of Antenna is Used for HF? They are called dipoles and they are About ½ a wave length long.

Why Do We Pull Them Out Horizontal Because they are have a wavelength long 80 meters – ½ is 40 meters or about 130 feet! That would be a lot of fun to support in the air!

Dipole Radiation Pattern Direction of Wire

If a Dipole Antenna is laid out Horizontally – Which Way are the Radio Waves Polarized? Oh Yes – Horizontal!

Brain Teaser Lets Think Higher frequency means the wave length is shorter A typical dipole is ½ wavelength long If the wave length got shorter – what happened to the antenna?

How Many of You Picked This?

The Bad News for People with Technician Licenses The only HF band you can use to Talk on is a little bit of the 10 meter Band. Ten meters is almost always above the Maximum Usable Frequency and will Almost always go out into space. (That’s one of the reasons its nice if some people take extra tests and get A general or extra license that allow them to use a lot of HF frequencies) Why are direct (not via repeater) UHF signals seldom heard stations outside your local coverage area? UHF signals are usually not reflected by the ionosphere (T3C-01)

So Are All Technicians just SOL? Not quite – the sun has an 11 year sun spot cycle. When the sun is really stormy it does a much Better job of ionizing the atmosphere. When we juice up the F layer in the atmosphere we can bounce Skywaves back to earth on 10 and 6 meters.

There is Another Catch In order for sunlight to ionize the atmosphere it has to be shining on it. That happens only during the day. At night the atmosphere starts deionizing and the maximum usable frequency goes down – and there goes our 10 and 6 meter Skywave Skip. Which bands provide long distance communication during the peak of the Sunspot cycle? 6 and 10 meters. (T3C-12) What is generally the best time for long distance 10 meter propogation via the F Layer? From dawn to shortly after sunset during periods of peak sunspot activity (T3C-09)

There is Also Another Way to Catch a Break There is a lower layer of the atmosphere That can be ionized for short periods of Time and will reflect 6 or even 2 meter Frequencies back to earth. It is called the E layer and its sporadic Ionization is called sporadic E. It particularly effects 6 meters. Sudden Band opening give 6 meters the nick-name “the magic band” What might be happening when VHF signals are being received from long distances? Signals are being reflected from a sporadic E layer (T3C-02) Side note – 6 meters requires a separate radio to use – right now there are few Church members and no plans to use 6 meters.

Related Question Which type of the following propagation types is most commonly associated with Strong over the horizon signals on the 10, 6, and 2 meter bands? Sporadic E (T3C-04) Do note that sporadic E is not a world Wide reflecting layer in the atmosphere So the places that “open up” are selective Not only in when it happens but where. The magic band (6 meters) often likes South America – good for our bilingual members but not a particularly good route for reporting emergency information around the ward or stake.

Getting Atmospheric Reflection with Lucky Shots Meteor Scatter Meteors leave an ionization trail behind them that can be used to reflect radio signals – especial 6 meters (the Magic Band) Which band is best suited for communicating via meteor scatter? 6 meters (T3C-07)

Another Lucky Shot Auroral Scatter The northern lights are atmospheric ionization. Not surprisingly we can bounce radio signals off them. Unfortunately, signals bounce all over in the pretty, but messy ionization area. The result is signals very in strength and are often distorted. What is a characteristic of VHF signals received by auroral reflextion? The signals experience rapid fluctuations of strength and are often distorted. (T3C-03)

Getting Your Ducts in a Row Normally air Temperature gets Lower the higher You go in the Atmosphere. In a temperature inversion you get cold air on the ground and a warm layer above. Air pollution people hate them – but they create opportunity for long distance radio communication in VHF and UHF bands.

What Does a Temperature Inversion Do for Radio Plan A – the change in air density of the warm air above bounces the signal back down to the ground, where it may bounce back up again. Like a ball bouncing on the ground – bounces weaken signals with each bounce. Plan B – the signal gets in the warm layer and Bounces between cold layers – lot less energy Loss. Catch – it skips everything in between and Comes at an unknown spot on the other end. What causes tropospheric ducting? Temperature inversions in the atmosphere (T3C-08)

Problems for Emergency Communication Simplex radio to radio will Always work if the two radios Are still in tact. Repeaters may or may not Be running. Sporadic E, meteor scatter, And tropospheric ducting are Not reliably available.

Here is Something that works almost all the time for 2 meters on up What mode is responsible for allowing over-the-horizon VHF and UHF Communications to ranges of about 300 miles on a regular basis? Tropospheric Scatter (T3C-06) You’ve seen these particles at work when you watch stars twinkle at night. Bounce the radio signal off of Particles in the lower atmosphere