March 8 2016 CLUB MEETING WWW.BCRO.ORG Loren Lawrence – Club President N5PUV

AGENDA 11-3-2015 INTRODUCTION TREASURERS REPORT OLD BUSINESS VISITORS MEET AND GREET TREASURERS REPORT MARK MADDOX OLD BUSINESS EOC Committee Storm Spotters Classes NEW BUSINESS Repeater Linking – Will Rogers TRAINING PRESENTATIONS TONIGHT: Radio Propagation 100 - Loren AGENDA 11-3-2015

Please start around the room, give your call sign (if you have one) and your name. Please help Welcome to all new (or long time since) visitors! Mine is Loren – N5PUV, Club President Meet and greet

Treasurers Report March 2016 Beginning Balance………………………………….1805.26 Income…….Interest…..….. .07 Dues………… 54.00 Expenses…………………………………83.40 Web Site 1 year…..83.40 Ending Balance……………………………………......1775.93 Treasurers Report March 2016 $

old business section

EOC Committee Updates needed Phase 1: (Immediate) EOC RACES Coordinator 1) As N5PUV now works full time in a closed environment, a replacement is required This person works with the EOC to help facilitate storm spotting, EOC presence and other business An Alternate can be chosen also This person should not be required to be Net Control Every time. EOC Committee needs: A calling tree for Net Controls able to get to the EOC to man the facility for Ham Radio A how-to guide on running the EOC Net Control (Simple) will be provided – Loren This is an absolute requirement Spotters that are trained in NOAA storm spotting classes Each needs to be set up on BC Alert – (Simple), to be apprised of upcoming needs in advance Program VHF and UHF radios on frequencies and Channels Manuals for Equipment – Laminated how-to attached to radios OLD BUSINESS EOC Committee Updates needed

Upcoming storm training NEW BUSINESS Throughout eastern Oklahoma and northwestern Arkansas, trained and dedicated individuals monitor the skies around their communities during severe weather events. These storm spotters provide first-hand severe weather reports to their local officials and to the National Weather Service in Tulsa, which are used to make critical warning decisions. Being a storm spotter not only means dedication but also training. The goal of the training is not just to recognize weather but to have some understanding of storm structure, which in turn better prepares the spotter for the extreme and unusual circumstances. Other topics covered include an update on the latest NWS technology and procedures, ideas for organizing/coordinating spotter groups, and important safety considerations. Upcoming storm training

Weather spotter classes in our area The training is free and requires no preregistration. The meetings listed below are open to the public. Date County City When Where 1/21 Thursday Benton Siloam Springs 7pm Finished 2/18 Thursday Washington Fayetteville 6:30pm 3/15 Tuesday Bentonville NWACC, Peterson Auditorium http://www.srh.noaa.gov/tsa/?n=spotter_training Weather spotter classes in our area

Additional old business? Next New Business

Repeater linking The BCRO club has 2 repeaters Centerton (2m) and Mount Whitney (70cm) Questions about linking the 2 have been asked There are advantages to doing this at a cost Will Rogers K5WLR, the repeater trustee has been researching this He will provide a summary of his findings Please welcome Will with his presentation Afterwards the club may make motions as required to move forward Repeater linking

Additional new business? Next Presentation

It is now time for the 1st of a 3 part series Radio Propagation 100 This one is the easy one. Loren’s Presentation

Basically, this breaks down into two parts: There are many types of radio propagation presentations on the internet mostly for Hams… Basically, this breaks down into two parts: What we all are familiar with involving HF propagation 80, 40, 20, 10 meters – and most of the books you read Modes for each Should you get a VHF and UHF mobile or HT radio 6 meter, 2 meter, 70 centimeter and Modes for each, etc, etc. etc But underneath those we know near and dear, are the structure of basic physics, just a touch those are what we are going to study tonight.

Those will involve more In Coming Presentations AFTER TONIGHT We might Cover more Propagation principles and theory. Those will involve more Math and formulas (I will try and steer from a few of those) Understandings of the Earth’s atmosphere (layers) Understanding of HF and different modes A lot more…but we don’t have all year So tonight we are going to focus on a more simpler underlying principles set often overlooked..and forgotten And do this in a much more relaxed topic without math (OK, I’ll leave most of the physics class out of this one)

So what is Radio Propagation 100? First, you have to get to basic physics What is a Radio Wave? Definition Merriam – Webster: Simple Version: an electromagnetic wave that is used for sending signals through the air without using wires Yep! now a little more…an electromagnetic wave having a wavelength between 1 millimeter and 30,000 meters, or a frequency between 10 kilohertz and 300,000 megahertz. Not so hard you all know all of this…

What does a radio wave look like What does a radio wave look like? Without getting into too much difficulty, here ARE AM and FM Radio Waves AM - Amplitude Modulation FM - Frequency Modulation Without getting into the physics of each at least that is how they look in 2D, Er, Flat that is

For our purposes tonight, just think of them as waves. There is more to them than that, such as they contain magnetic and electrical properties. Let’s not get into 102 or even 103 yet… http://www.radio-electronics.com/info/propagation/em_waves/electromagnetic-reflection-refraction-diffraction.php

Here is another look This might look more familiar. We are not focusing specifically on modes, as most of you Hams know this stuff. But eventually it does matter – Ever go under a bridge listening to AM radio?

basic principle: when radio waves travel they interact. These interactions cause the radio signals to change direction, and to reach areas which would not be possible if the radio signals travelled in a direct line.

The 3 Basics of Radio Wave Propagation: Reflection Refraction Diffraction How do they interact? They follow the rules of physics. Much like the light our eyes see. But remember, there are many differences in frequency and how our eyes see biochemically. So that is not a correct analogy to use.

Reflection of light is an everyday occurrence Reflection of light is an everyday occurrence. Radio waves are similarly reflected by many surfaces. For relatively short range communications, many buildings, especially those with metallic surfaces provide excellent reflectors of radio energy. There are also many other metallic structures such as warehouses that give excellent reflecting surfaces. As a result of this signals travelling to and from cellular phones often travel via a variety of paths. Similar effects are noticed for Wi-Fi and other short range wireless communications. An office environment contains many surfaces that reflect radio signals very effectively. Reflection http://www.radio-electronics.com/info/propagation/em_waves/electromagnetic-reflection-refraction-diffraction.php

REFRACTION The concept of light waves being refracted is very familiar, especially as it can be easily demonstrated by placing a part of stick or pole in water and leaving the remaining section in air. It is possible to see the apparent change or bend as the stick enters the water. Mirages also demonstrate refraction and a very similar effect can be noticed on hot days when a shimmering effect can be seen when looking along a straight road. Radio waves are affected in the same way. It is found that the direction of an electromagnetic wave changes as it moves from an area of one refractive index to another. The angle of incidence and the angle of refraction are linked by Snell's Law that states: n1 sin (theta 1) = n2 sin (theta 2) But we said no formulas: Let’s just say it CHANGES DIRECTION

DIFFRACTION To understand how this happens it is necessary to look at Huygen's Principle. This states that each point on a spherical wave front can be considered as a source of a secondary wave front. Even though there will be a shadow zone immediately behind the obstacle, the signal will diffract around the obstacle and start to fill the void. ..For a radio signal a mountain ridge may provide a sufficiently sharp edge. A more rounded hill will not produce such a marked effect. It is also found that low frequency signals diffract more markedly than higher frequency ones. It is for this reason that signals on the long wave band are able to provide coverage even in hilly or mountainous terrain where signals at VHF and higher would not. It is found that when signals encounter an obstacle they tend to travel around them. This can mean that a signal may be received from a transmitter even though it may be "shaded" by a large object between them.

Refraction of waves involves a change in the direction of waves as they pass from one medium to another. Layers of Air for example Diffraction involves a change in direction of waves as they pass through an opening or around a barrier in their path. Doorways, Building edges, mountains for example Confusing point, what is the difference between refraction and diffraction (Besides both having the word Fraction in them)? http://www.physicsclassroom.com/class/waves/Lesson-3/Reflection,-Refraction,-and-Diffraction

But what does all this mean to you? It means everything. Without these 3 principles you would not hear most radio communications. They would simply be LINE OF SIGHT and travel on without you picking them up. And knowing these principles, you can use them to your advantage: Antenna placement and direction Placing yourself in the area of best reception Radio direction finding to name a few.

One last thought for Radio Propagation 101 On all of these, does the Radio frequency matter on how well they react to these 3 principles? As you might expect, you bet’chem! In fact, it’s a study all to itself! Guess what’s next? Next time we might Discuss FRIIS and a few of his friends Or, just keep it simple http://www.rfcafe.com/references/electrical/NEETS-Modules/NEETS-Module-10-2-31-2-40.htm

THAT is all of Radio Propagation 100 Next month, 101 And then to Infinity and (hopefully) not beyond.

It’s that time! Thank you! Please help move tables and chairs – 73 and 75 - LOREN