Extra Class Lesson 9.1, Basics of Antennas

[@applepie2775]

Thank you so very much! You're that patient teacher I always wished I had when I was a kid with a hunger for learning such things. Now decades later I've finally found my teacher and I feel like I'm re-igniting some long forgotten fascination with this world of things---forgotten and left behind in frustration.

[@markdisbrow7184]

I have a bachelors degree in EE and this is incredibly helpful. This sort of teaching is absent in formal education these days. Thank you.

[@davecasler]

Thank you

[@francismcclaughry3794]

I'm glad he is out here two. I have a general ticket and have played around with antenna since i was a kid. but i did not think that I could kill some one because of not thinking. and that I wanted my antenna to work from east to west. and dave used several big words that the meaning did not compute in my mind. Yes there is a lot that is not taught.

[@maniac50ae14]

How do they teach this then? I didnt go to school so id have assumed this is how its taught

[@emailshafihusain]

Very informative. And it is so rare to hear someone so articulate. Thanks! 73 from India. This is VU3BQY.

[@josecarlosribeiro3628]

Good afternoon Professor Casler! I am studying about antennas and radar by myself applied to remote sensing. Yours teaching and explations are so clear and high quality! Congratulatiobs!👏🏾👏🏾👏🏾👏🏾 "The man is eternal when your job is continuous! God bless you and have a Merry Christmans, for you and your Family! Jacareí- São Paulo-Brasil.

[@k5rpb]

As always, Dave has a way of explaining the complex to a guy like me so that I can understand. Thanks, Dave! I'm taking on the Extra exam and using the ARRL study guide as my text. But, I always come running to this channel to get the classroom version which makes it all clearer.

[@carlmckinney196]

I sure do wish I had these videos when I studied for my licenses! What a great refresher!

[@SRINIVASMALLAREDDYPETA]

I really appreciate the way the topic is presented and superbly explained.. Thanks a lot Mr. Casler.!

[@davecasler]

+SRINIVAS MALLAREDDYPETA You're welcome!

[@johnallsopp8260]

Superb David, I taught the RAE here in the UK using many of the tips of explanation found in your video series. 73 de John Allsopp G4YDM Washington,(Ancestral Home George Washington) North East England. Stay safe and well in the U.S.A.

[@HouseOfBane79]

OMG I love this guy!!! I wish I would have had him as a teacher when I was in school, I'd probably be an engineer rather than an electrician!!!!!! SUBSCRIBED

[@จรูญดําแดง-ฌ6ฌ]

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[@peglegpete6656]

Never to late.

[@stereopolice]

You sir are one fine teacher. Thanks for the video.

[@johnpierre1898]

If I put a vertical on top of a steel shop building, will it need radials?

[@jonathanokocha2358]

I would like to design my own antenna for a Radar receiver!. Outstanding Lecture!!! My first introduction to Antenna Design. I started reading a textbook on Antenna. This video is superb and really summarized with all details. Thank you, sir!

[@VanishingNomad]

Improve your antenna before investing in an amplifier = WRONG!! The correct way is to invest in whichever one presents the sweet deal first. Get the other one later. Great video btw!! I learned a lot from this one!

[@glowingone1774]

Better antenna is almost always a good upgrade.

[@carmelpule6954]

Excellent contents and a gentleman as a presenter. There is many hours of preparation for such a video. The priority points are mentioned and his experience does admit that practical performances are not always as theory stated, His best statement concluded from his experience is ," Everything can affect the performance of the antenna." My congratulations on your presentation and experience.

[@davecasler]

Carmel Pule' Thank you

[@RAndrewNeal]

I subscribed after watching one video. You're up there with w2aew when it comes to explaining this sort of stuff. It's also so much that I can't learn it all from watching a single video a single time.

[@nedwardj]

Thanks for having both thorough knowledge, and rock-solid presentation skills. You rock!

[@MarkRose1337]

This is by far the best explanation of antennas I have ever come across. I've learned more from this video than in countless hours of browsing the web. Thank you!! May I suggest adding the topics covered to the video description to help others find this amazing video?

[@davecasler]

Mark, thanks for the suggestion. I've updated the video description. 73, Dave

[@malamati007]

There are myriad ways to screw up the use of "myriad"....kudos to you, David, for knowing how to use the word correctly. Oh, and BTW, just an exceptional video on a very difficult (for me) topic. Thanks!

[@lydiafrancis5185]

Thank you from the bottom of my heart for this video. You made the pages in my manual come to life!

[@jedihakan]

Thank you sir, I wish I had courses thought by people like you.

[@tombra4ril]

Most useful and understandable Antenna explanation I have heard. Thank you sir, remain blessed.

[@vaishravanas4234]

Thank you sir. This is the best explanation of antenna patterns I have ever watched. Very intuitive description , superb presentation and indeed accurate.

[@harrisonfamily7576]

Dave, you do an amazing job explaining all this stuff. Spent many hours listening to you. THANK YOU.

[@xxilluminatixxxx]

My old TV's antenna is a piece of electric wire hanging from it... It may not be the best, but man this things are easy to make... Great video by the way! Very informative.

[@larryak0z672]

Some people think that you should use a certain length of coax between your radio and swr meter when adjusting your antenna. What are your thoughts? Thank you. Larry

[@BarelyAPilot]

You are an excellent teacher. Very clear explanations of hard to grasp concepts.

[@davecasler]

Tyler Snowden Thank you!

[@hamradiox]

Studying for my Extra, thank goodness for your channel! Thank You!

[@fikretcolak6507]

Thank you Dave, great explanation. So much beneficial for me to understand the topic.

[@JoeShockey]

What is a "dipole" antenna? Why is it stretched from west to east, don't antennas go up and down?

[@EmrysMaier]

Your description says this video is obsolete, but the video linked is private. Is there an updated updated video link?

[@davecasler]

See www.ke0og.net/extra for the current links. You will need to be an ARRL member to view.

[@stormbytes]

Might be "obsolete" as far as the current HAM radio exam. Certainly NOT obsolete in regards to real life learning. Outstanding presentation. Wish I knew which "book" he's refrencing.

[@Tannerys]

He's referencing the ARRL Extra Class License book, this may be a little out of date but ~95% of the content hasn't changed much in the last 10 years.

[@isolatedgirl5276]

what should be the radiation pattern of multiband antenna

[@johnsherrill6411]

David - I have thoroughly enjoyed your instructional videos in preparation for my advancement to Extra Class license. 73's

[@codijack9577]

Best ever explanation of antena. Thank yo, you are great, talented teacher.

[@ahmadsayem]

Sir you're good!! Thanks for your contributions, this is S21TB, 73

[@davecasler]

+Ahmad Sayem You're welcome!

[@dandypoint]

A dipole in free space hads 2.15 dBi gain but not when it’s halfwave over real ground as you state at the 18:40 point in the video. It has more like 6, 7 or 8 dBi. Many people get this wrong.

[@jwrosenbury]

This story might help some people understand radiation resistance: Back about the turn of the twentieth century a young patent clerk was trying to understand why antennas generated far fields. Applying Maxwell's Equations generated a near field, but no far field. After pondering the problem, he discarded everything everyone knew about physics and invented Special Relativity to solve the problem. It turns out that accelerating charges changes their inertial reference frame and causes them to emit photons. One way of understanding antennas is to see them as guides to accelerating electrons so the photons they emit go in the directions you want. But rather than teach every HAM radio guy Special Relativity, they started teaching "Radiation Resistance" instead. That worked for a long time, and Electrical Engineers forgot the physics behind their craft. But it's a nice tidbit to know, even if it's not that practical.

[@petevannuys5642]

May I ask for your assistance with apartment for antenna installation simple type antenna ?

[@sludge1298]

Sure am glad this exists! Thank you, Sir!

[@Tendieee]

Deep. Well done. Better than 5 yr degree programme.

[@warrennetherton6011]

Wow, this is a very good explanation. Thanks, Dave!

[@n0rg]

Love your videos and how you present the material. I always learn something new. However, you've probably never been to Western Nebraska as it is NOT flat. Once you get past North Platte, you're rising in elevation and the hills become more apparent.

[@intellilab-rw8qi]

What playlist is this on? Tks dave😊

[@axelsolhall5830]

What is the best type of antenna to use if i want the main lobe to be a cone with maximum gain around the axis in the centre? I want a drone to to follow the maximum signal strength, in other words, the drone should always be going towards the central axis in the middle of the main lobe.

[@joystaton2497]

Do you have a video where you explain this in terms of Earth specifically?

[@WaltWashburn-up3np]

Video link for updated version is "private" and thus not accessible. Thanks Walt KT0D

[@yelyab1]

What is the relationship between receiving antenna configuration and transmitting antenna configuration for shortwave radio frequencies? My impression is that reception is less precise than transmission, and the most important characteristic is height. I want to try a weather ballon just under 500 ft with a 1/2 or 1/4 wave antenna out of a rigid material in a horizontal mode. Compass heading may have to be magnetic, ie, north- south. I’m a ME by education and practice. Be kind.

[@ki6eeo]

David, U R STILL THE ONE !!! Thank you so much for your lessons ! Alex

[@davecasler]

ki6eeo You're welcome!

[@raghavsamba]

complex topic but well explained, i feel video needs to be watched multiple times to get better understanding....

[@yelyab1]

What do the new satellites looking at the edges of the universe use for a radiation pattern. It must be extremely focused because signal strengths are not in the megs watts.

[@mooredelira]

Great, I found your amateur extra videos and your general videos.

[@davecasler]

Good luck with your studies!

[@mktwatcher]

Why does the Signal Strenght indicator show the Signal is Stronger the futher away it is from the dipole antenna's element (radiator). It's my understanding that an RF/Electromagnetic Wave falls in strenght based on the Inverse Square Law: The Strength of the EM field is Inversely Proportional to the Distance Squared from the Radiating Antenna.

[@jeffguidry5099]

I need to know if an end fed antenna will work if shack is in a valley

[@forbaldo1]

my god I almost understood I checked a few words and it's coming clearer thanks from don the welder

[@mooredelira]

Great, glad I found you. Why did your video go obsolete? Do you have videos on the general license?

[@davecasler]

The technician videos are now available learn.ARRL.org. All of my training videos are moving to the league website. If you want to see the technician website, go to KE0OG.net/training. They are all listed there. The general videos are in process of being moved to be hosted by the ARRL.

[@yelyab1]

If the radiation pattern can be reduced, is it assumed that the antenna has more range? The power is concentrated over a smaller volume cross section therefore the pattern should be elongated?

[@thehandleiwantedwasntavailable]

Started a diy double cross antenna build for receiving satellite images and somehow ended up here in the weeds 😂

[@aloisiosimoni165]

I do have a question: what is the inportance of: R, R2, C, C2, Z, and Z2 in a broadcast fm antenna, most of the Engeeniring look for SWR, and dont care about the anterior measurements (R, R2, C, C2, Z, ad Z2)

[@jihansalah7148]

would you mind explaining the fundamentals of patch antennas

[@MrHugomiguelcandeias]

Mr. David, thanks to you i know more about RF

[@mikeZL3XD7029]

Thanks! from ZL3XD

[@truculenttabasco]

Very informative, thank you. Now on to the not obsolete video, haha.

[@helloman1976]

Brilliant! You're an excellent teacher, thanks!

[@aldrichperez9981]

Which is the best antenna to transmit and receive 915mhz frequency ?

[@poorman-trending]

The link in the description doesn’t work. It says the video is private…

[@vince_only_way_is_up]

can you make a Yagi spinning antenna and get benefit of isometric antenna ??

[@SeaJay_Oceans]

GREAT Video ! Thank you! Better than a paid-for University Class...

[@corax2012]

Now I understand why there seems to be so much experimentation with antennas. I have LOS from my mailbox 600 yards to my workplace through a closed window. Being a run down rural road. I'm going to build a disk Yagi and mount it inside a newspaper tube aimed down the street. :)

[@trollhummer]

You are a rock star teacher!

[@deuce-way1440]

What do you mean by two "S" units? @15:34

[@jorgeguzman9955]

A flash light reflector be made of plastic can act as a reflector for my antenna how to make it

[@ambientsoda106]

Degrees of Assemoth; sounds like some fantasy game or folklore...lol ...but how would you know what agnle or direction the em wave is moving in, in terms of maxwells law of thre evectors electric field, magnetic field and motion.

[@matthoward8546]

21:24... under water pattern??

[@williamlindsey5906]

Wow Dave . Looking good!

[@azanisahal1043]

Hi Dave, i need your help in my project about an adaptive antenna array. Is there any lesson video that you had done before that maybe will help me a little about my project. :)

[@davecasler]

Unfortunately I'm not familiar with any. I'm not sure what you mean by "adaptive" antenna. Please tell me more.

[@soloban81]

24:34 Dave - your antenna must not be that bad! I heard you via my 20m dipole clear as day in N. Al last night talking to a station in HI on 20m - W5CSW

[@davecasler]

+soloban81 Indeed! I was talking with KH6CB at the time on 14,290 kHz on the 20 meter band. I often hang out somewhere near that frequency--perhaps I'll catch your CQ! 73, Dave, KEØOG

[@soloban81]

+David Casler Yes it was that conversation. I was listening in and thought man his voice is familiar and then heard your call sign and it clicked.

[@soloban81]

+David Casler /ae as of tonight. Big thanks for the videos!

[@davecasler]

+soloban81 Congratulations on the upgrade! Perhaps we'll hook up on 20 or 40. 73, Dave, KEØOG

[@ishkool8664]

Thank you Sir! You just made me a better engineer :)

[@grostig]

OBSOLETE? I tried to go to the new link for version 11, but it is "private"! Anyone know what is going on?

[@stevemacbr]

Hi, can you do a video on ceiling mounted, omni-drecional dome antennas, used with repeater amplifiers in the mobile cell phone frequencies (1800Mhz )? - How they work & construction.

[@davecasler]

Steve, I haven't worked with any of these. I see several advertised on the web, all for cell phone applications. Perhaps another viewer will have more information. 73, Dave

[@kobert2007]

Well done Dave.

[@terencebarfield5864]

David Sir - respect how do you get the antenna to transmit at a lower angle ???

[@davecasler]

Put the antenna up higher. As you push it higher, the main lobe tilts further down to the horizon. There is a limit on this--as you elevate past one-half wavelength, the main lobe starts to split into two lobes.

[@Satchmoeddie]

Hey there Dave! Thanks for you & all the other You Tube University professors. My extra class status posted to the FCC data base, last week, or the week before. I managed to sail through the Technician & General, mainly from repairing AF & RF stuff for the past, uhhhhhhmm, erm, eh, carry the, and add the, uhm, wow. Let's just not go there. Anyway, thanks for explaining why a dipole does what it does & how the test got their figures. My QTH in between two AM stations, that tend to wreak havoc with everything. Antenna types I was never bothered by, were/are one of my weak areas. I am up in Colorado now, again and will be headed out your way soon. Who knows? Maybe? I generally drive & I don't even like even using a cell phone, while doing so. 73 KI7AQJ

[@davecasler]

+Seth B Congratulations on your upgrade!

[@TriPham-xd9wk]

If we use telegraph type of communication system there can never jam possible because unpredictable amplitude or timing

[@adelarsen9776]

Element orientation does not always equate with polarization.

[@daslolo]

and 50 ohms at the feed point, is that the impedance of the wire to the amplifier?

[@davecasler]

Yes, that's the impedance of the cable.

[@vr4edu985]

Love it! Not sure what software is being used but there is a slight delay between video and audio. I am studying for my General and also need to put up an antenna. I love this stuff! Thanks!

[@davecasler]

Donna, thanks for the pointer. I'm getting close to redoing this video for the 11th edition, and I'll take another look at video/audio sync. Good luck with your studies! 73, Dave

[@jermiinus]

What book are you referring to?

[@davecasler]

The ARRL Antenna book. www.arrl.org/shop/ARRL-Antenna-Book-23rd-Hardcover-Edition/

[@vr4edu985]

Okay. Thank you!

[@ronwiderman667]

How can you detect a radio control transmitter channel signal operation strength and frequency with a meter?

[@davecasler]

If you're quite close to the transmitter (a couple feet) you can use a frequency meter. Otherwise you'd need a wide-band SDR radio that covers a wide-enough range to pick up the signal.

[@nickfish03]

Thank you very much for these videos. I know it took a LOT of time and energy to produce. This video helped me understand antenna gain better. 73 KK4VYS

[@johndeacon2101]

What are you using for a balun on your 80 meter loop?

[@davecasler]

I don't have that antenna anymore, but what I was using was a 4 to 1 balun. It really was the wrong balun. If I ever put up another large horizontal loop like that, I will definitely updated for better feed point.

[@codyherrin6939]

Great video, thanks for putting it together. I look forward to checking out more of your videos

[@hoseingame2203]

fantastic video. Thank you for sharing a lot of beneficial information

[@niteshad9]

New video is marked "private."

[@walther89]

can you explane quickly, so devices have their own Gains and Losses, Loss in dB and Gain dBi, what the loss means, which way is better,

[@DutchyBart]

Hi David, is there a diffrence between antenna resistance and radiation resistance? And how do you determine de antenna resistance in practice? Thank you for the video, helped a lot!

[@davecasler]

Radiation resistance is a theoretical resistance that corresponds to how much of the power offered to the antenna actually gets radiated. The rest gets converted to heat. I don't know of any way to measure it directly unless on an antenna range, and even then it's rather esoteric to measure and must be inferred from signal strength at a receiving site. The idea is that if the resistance (impedance) of an antenna is 50 ohms, you want the radiation resistance to be as close to 50 ohms if possible. In that ideal case, there are no losses in the antenna itself.

[@Jtoksa2]

A question to experts out there: I bought a log-periodic antenna for 4g data (the type with white wegde-shaped plastic housing, 30-40cm long) and when I measure its impedance at the remote end of the coax cable with a simple TDR circuit, I see a near (but not total) short circuit at the antenna end, and when I measure DC resistance, also at the coax end, I get 3 ohms. Is this normal? Is the antenna not supposed to be matched to 50 ohms so that there should be no reflection at all?

[@davecasler]

Yes, it should match 50 ohms at the design frequency, but likely not at other frequencies. Many perfectly good antennas measure zero ohms (dead short) or close to it at DC. The DC resistance is often completely unrelated to the RF impedance.

[@Jtoksa2]

David Casler Check this picture, I am driving a fast rise time signal up the remote end of the coaxial cable (length 10m) and after 90ns I get back a reflection which looks nearly a short circuit but not quite. Is it still possible that the impedance is matched at the frequency range that the antenna is meant to operate at? Or is the antenna defective? It seems to work because I am right now accessing the Internet through it :-) dev.gruppo.fi/~jaakko/IMG_20170525_122459.jpg Here is also a picture of the antenna itself: dev.gruppo.fi/~jaakko/IMG_20170525_143315.jpg

[@davecasler]

A fast-rise-time pulse has a very broad frequency content, and the antenna and feedline react to these different frequencies differently. If your fast rise time pulse is in fact a step function, you have all frequencies in the response. If you are looking at the response unit impulse then the result is a response curve that translates as a broadband frequency response. Since no such physical system can exist, some of the frequency components will get lost, resulting in a reflected pulse that is not clean. A transmission line has its own characteristic impedance, which is a weak function of frequency. The antenna's impedance is generally a strong function of frequency. I think you are trying to analyze the system in the time domain. I suggest using the frequency domain and using sine waves rather than step functions. Good luck with your experiments! 73

[@Jtoksa2]

David Casler Thank you for your great explanation! I recently dug up my old textbooks from thirty years ago about transmission lines and related subjects, and plan to brush up my understanding of those subjects as soon as I have the time :-) The 15€ ($15) Aliexpress antenna works great, though, as I seem to be getting better speed than before.

[@kenyinelson1272]

Sir , ve made it better to understand and develope .thanks for the video

[@Camillus419]

at around 30minutes. why is it horizontally polarised if the book is using the direction of the H-field rather than the conventional E-field?

[@davecasler]

The E-field is horizontally polarized. What we're looking at is the elevation profile, so that's "in the direction of the H field, which is, of course, vertical" The only reason the League puts this confusing stuff in is because there's a confusing test question in the question pool. The bottom line is simply that it's showing far-field signal strength in the vertical direction.

[@Camillus419]

David Casler thank you.

[@galaxy0088]

Great information. Getting close to my extra. Thank you

[@mooredelira]

I like how you present your instruction. Is there a list of simple pieces of technology that will help us incrementally progress? I'm a retired high school math & science teacher

[@davecasler]

Thanks. I've tried creating videos that touch on electronic fundamentals including demonstrations. But my audience doesn't seem to resonate with those, so I am sticking to answering viewer questions. Most of the questions are about grounding and antennas. But I do try for a little variety.

[@VE2FET]

Excellent presentation! Very very well done! Bravo to you!

[@daslolo]

why do we visualize in log scale? it seems to be making things more difficult to understand visually

[@davecasler]

Actually, a log scale allows visualizing numbers that are tiny and huge all on a manageable scale.