Impedance and Ham Radio Antennas Explained
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- เผยแพร่เมื่อ 19 มิ.ย. 2024
- In this video, we talk about antenna impedance, what it is and how it's different from resistance.
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7:52 is where Ape really hits it out of the park. The concept of actually adding either capacitive reactance or inductive reactance by changing the overall length of a dipole is SPOT ON! I have never heard any lecture or any antenna book actually come out and say this, but it is an accurate statement. BRAVO APE for teaching this very valuable concept. 73
Thanks for checking it out WEC 👍
Yes I agree although reflections by Walt Maxwell does go into it also more should be mentioned of what happens to reflected power as its not all lost and certainly doesn't damage equipment as many think
@@paulm0hpd319 You might enjoy Eric Dollards presentations
Your way of explaining these not so intuitive concepts is really clear and to the point. I’d would also appreciate some info regarding Smith charts like another person mentioned. Thank you for sharing your knowledge!
Hey Jorge, glad you like the videos! I add Smith Charts to the list.
Another awsem video SA, thank you for all you do!
Hey Ghost, glad you liked it... 👍
Thanks for taking the time in creating this video. I learned a lot.
Glad you liked it G, thanks for watching 👍
A smif chart video would be helpful for those studying for their extra. There are questions in the pool on the chart.
Hey Shooter, I’ll put the smif chart on the list 👍
Man you did it again with an excellent video. You really are an asset to us all. Thank you!
I appreciate that!
Great explanation, Ape! Thanks and 73!
Thanks Ed, glad you liked it!
Unbelievably well done! Thank you! I’m a GMRS Guy that got talk into being a Ham guy as well! I have been working on building a GMRS repeater system in our area for the last year! Its doing well…I sure have learned a lot about antennas the hard way and the expensive way! Anyway this video of yours really helps simplify ( Clear up) what is really a complicated subject! Next to info like this NanoVNA is an awesome tool to own! Extremely useful antenna diagnostic tool… As with most complicated things information is everything… Thanks for all your videos I always learn something with everyone I watch.
That's awesome David. Welcome to Ham Radio 👍
You took me back a long way there Good Excellent demonstration . Cheers for Noo
Glad you liked it Trig 👍
Really enjoyed this video. Helped demystify some concepts for me. tnx
Awesome, glad you liked it Stephen 👍
Thanks a Stack for a Wonderfully Informative, yet 'Simply' explained vidclip .... Best to You, Yours and All, ..... from New Zealand
Thanks for watching Keith, glad you liked it 👍
Thank you so much for this upload very interesting information
Glad you liked it KYM 👍
Man this helped out a ton, thanks!! Will be watching your smith chart vid later this evening. 73's
Thanks R L, glad you liked it 👍
I’m halfway through getting my Ham license, and this topic is not an easy concept to understand… I’ll be watching more of your videos!
It’s confusing at first but you will get it, good luck on the test 👍
Excellent presentation, thanks Ape
Thanks Kevin 👍
Excellent video! Spelled out in clear language that just about anyone can understand. Heck, I'm an Extra and I even learned something (what the capacitor on an EFHW is actually for).
That's great feedback Grimace, thanks man! Glad it was helpful.
Yay!,
Back in the day of me being a trainee electrician, we had to calculate all of this sort of stuff for electrical circuits in an exam situation, I'd already passed the written test for my Ham radio licence and I found it quite easy, lots of electricians failed this part of the exam.
This sort of thing can be really intimidating, if you've never worked with AC theory that depends on frequency as a part of the equation.
My advice is, if you have something like the ARRL book, read and know the sections on basic AC theory, yes it is REALLY dry and boring, but it will hold you in good stead for when you go to build and tune antennas!
Awesome video, Ape.
Thanks Mike, and yes the ARRL handbook is a fantastic resource but that too can be intimidating at first. Thanks for watching bro 👍
Great Video, Very well explained
Thanks Casey, glad you liked it 👍
Great video. Just got a VNA a month ago and like learning how to use them.
Hey Derrick, that VNAs are pretty cool. Thanks for checking out the video 👍
Excellent explanation.
Thanks, glad you liked it 👍
Nice video with some good technical content.
Thanks Ryan, glad you liked it!
You’re teaching me all the things I memorized (but didn’t understand) to get past my Extra Class exam back in the 90s 😝 Seriously. Thanks man.
Now I wanna see a System of a Down t-shirt in a future video 🤘🏻
Glad to hear its helpful, thanks Max!
Very informative video, thank you. I also use a Nano VNA, but until you explained it I had no idea what the heck the Smiths Chart was! In the UK, lower level license holders, like me, an M7, are restricted to only 10 watts. Some say this is a good thing, in that it teaches new Hams the importance of an efficient antenna system, we can't just turn up the juice to get out further! I actually agree with this, so any info on improving my antenna systems will be helpful, so I, for one would appreciate an in depth look at the Smiths Chart, and any other indicators of efficiency. I appreciate that this is a bit of a niche topic, so not a priority, given the likely number of views, but it would help. Failing a video, could you point me to another Tuber who has done a video on the topic. Keep up the great work Jim M7BXT
Hey James, being limited to 10w does "encourage" antenna expertise. I added smith charts to the list, in the meantime these might help. th-cam.com/video/QX8H8U7c71w/w-d-xo.html and th-cam.com/video/uACLz0lHm10/w-d-xo.html
Very good video!
Glad you liked it BA!
Great info as always. Would like to see the one on smith charts as well 👍
Thanks Jason, glad you liked it. I put the charts on the list.
Outstanding explainer. I use a RigExpert instead of a nanovna, but they both get the job done. I'd love to see an in-depth smith chart video!
Thanks for watching FEP 👀👍
The Smith charts!? How soon is now?
Nice informative video.
Thanks for watching Thump 👍
Enjoyed the video and it is coming, for me at the right time. If you count comments I'm with Scott, W9AVA, I would watch one of your basic/easy to understand video on smith charts.
Hey Bill, I will do one on them in the future. Thanks for watching the video 👍
@@TheSmokinApe looking forward to it.
Wow! Congrats! A technical video, in ham radio-world, on antennas, which seems to be correct! (It's a rare find! 😄). I haven't watched this all, but the bits I dipped into seem good! 😀
LOL, thanks Tim 👍
Thanks a lot
Great video and you now have me worried about how bad my antenna is. I would also like to see a good video on the smith chart and what it all means. 73.
LOL, the truth of the matter is the all antenna systems have a problem/issue/compromise somewhere. Just go out have some fun and make improvements as necessary over time. Thanks for watching Steve!
No impediment to impedence importance impression. Impression imparted. I'm pumped.
Lol, thanks for watching Karl 👍
Hey sir. I really appreciate your videos. Always informative. I am curious about something though, when you have a Smith chart and it shows a bunch of circles really tightly wound together does that mean you're antenna is doing well?
The tighter around the center the better 👍
I enjoyed this. Add me to the list of those looking forward to the Smith Chart video.
Wil do Mike, thanks for checking out the video 👍
Great video, Ape! Many thanks!! I'd watch a video on Smith charts.
I have a NanoVNA, but I've never used it in the field. I thought about it last week, at the Don Edwards San Francisco Bay National Wildlife Refuge (K-0189). There is public access from San Jose, Santa Clara County, and from Fremont, Alameda County. I'd never been to Don Edwards before, for any reason, and I went to the San Jose side to check it out. With short trees and pedestrian trails, I couldn't find a suitable place to string my EFHW in any configuration. I finally decided to try an inverted-V from the rear deck of the (closed until further notice--Chicom Crud and all that) Environmental Education Center, using a protruding roof beam as the apex of the V. My inverted-V turned into an inverted-something-or-other, as I ran out of space before I ran out of wire. I thought it would be interesting to measure SWR in that configuration, but what I thought was clearing sky turned out to be just a space between storm fronts, and the downpour began quite abruptly at that point. I did get a few QSOs on 20m, FT8, from Utah, North Dakota, Kansas, and Iowa.
LOL @ inverted-something-or-other!
And this understanding has become a lost art.
Years ago this was a common understanding … we all learned and understood this.
Not a totally big deal but it becomes a big deal when your running really low power or really high power.
Definitely helps you learn to MacGyver a solution on the fly when you need to.
Most all the fancy analyzers will show you the sub components of Z.
What I don’t see TH-camrs doing that would be nice is teach new hams how to read that wonderful info and what it means when your SWR is 1.2 but your reactance components total 40 and the ohmic is 10.
Thanks for all you do.
Good explanation
Please consider going just a little deeper in another video.
Hey D30W, I agree that this type of info can be a little hard to come by on YT. Thanks for the feedback! I do plan to continue exploring the topic in videos.
I love the smell of impedance in the morning!
Lol., that’s a good one ☝️
Go for that smith chart, please. That would be great
I’ve been using them more in my videos and have some more planned, thanks for the feedback 👍
I think I got it Son! ... If your "Impe" "dance" ain't right, then your antenna can't dance! Nice job covering the subject Ape! 73 - KF6IF
Lol, glad you like it Phil 👍
This is a great video. Complex high tech information delivered in manageable bite size chunks. M7MDO
Thanks MDO, glad you liked it!
Thanks for the video Ape. I don't think you covered the case of ladder line because as I understand it, the ladder line will not dissipate heat in the same way as Coax. On another note, I can really see what SWR does in a more dramatic way with the Amplifier because instead of a few watts coming back, it can be hundreds even with a lower SWR in the 1.7 range.
Ladder line? Ain’t nobody got time for that!
If you visualize Ladder line like train tracks with EMF rockin and rolling down the center you then understand how it was improved and used inside a metal tube to stop RFI from other lines "reacting and impeding" and then finally one conducter as a shield and the other line as the center conducter called coaxial cable. Using Maxwell and Lorentz's math to send the RF train down any 2 conducters or for really high frequency EMF down a square, round or triangular tube called a wave guide is mega fun. Get the math wrong and you enter into the world of melted antennas and swr induced magic smoke. 73 kd9uqe
@@TheSmokinApe But . . . But . . . Chuck said . . .
Great info, Ape !! ...Making sure I have this correct.....Assuming the usual std 50 ohm radio, coax & antenna feed point at the freq of interest & making diy antenna (yagi) optimization adjustments......If NanoVNA shows antenna R= 50, X=0 & SWR = 1 : 1.00 the antenna system is Resonant & perfectly Z (impedance) matched to 50 ohms......However, any Significant X (how much Is significant ?...>1, >10, etc) the Driven element Length & Feed match Should be adjusted out to Minimum X reading (more Resonant) & Closest to 50 R, 50 Z & Lowest SWR ......X is Less desirable than R Deviations from 50 & should be corrected 1st .... ??
I believe that is correct!
Nice and simple explanation 👍 Shouldn't "J" be lowercase (06:00) ?
Well, your prolly right on that. Thanks man!
I bought a Bearcat 125AC hand radio, live in Orlando FL (Orange County). I need an antenna that will allow me to listen to FIRE/EMS in case of Emergency power outages. Can someone help me chose an appropriate antenna??
I have been really happy with Comet and Diamond antennas, just make sure you get them from a reputable dealer.
It's all voodoo until the Ape lays it on the table. Thanks OM
Haha, thanks for checking out the video Shawn 👍
Is SWR (without a tuner) an indication of resonance?
if you have a perfect 1:1. Resonance is when there is no reactance...
You have the best lectures in ham radio, I always understand 100% the topics you cover here. Thanks! Suggestion for a video: SWR vs actual power radiated. For example, does a 1:2 SWR mean I’m only radiating half of the power that arrives at the antenna after the coax? Thanks!
Thanks Levy, glad to hear you like the videos. Here are two I did that should help with SWR, Return Loss and Transmissions lines: th-cam.com/video/QX8H8U7c71w/w-d-xo.html and th-cam.com/video/AE1Mvlzi4gI/w-d-xo.html
@@TheSmokinApe thanks, man!
The subject of resonance in multi-band antennas would be a good topic for the Smoking Ape treatment. Using a RigExpert to analyze a friend’s ARRL EFHW, we found that impedance due to inductance and capacitance summed to zero at numerous frequencies. That’s generally considered as the definition of a resonant frequency. On the Smith Chart it would be seen as a crossing of the horizontal centerline. Is there an additional criterion for resonance that I should consider? How does your statement that resonance only occurs at a single frequency (which is what I believed also) align with the fact that there are numerous examples of frequencies where reactance is zero?
Hey Shannon, I am going to guess you were measuring through a transmission line. So what you are actually seeing is the impedance of the antenna system and not the isolated antenna, which is fine. The transmission line does effect the overall measurement. I'll be doing a video on the effect of transmission lines at some point. Thanks for watching the videos 👍
@@TheSmokinApe - exactly right, probably about 38 feet of M&P UltraFlex 10.
Is there any reason I couldn’t connect my RigExpert directly to the EFHW via an adapter or jumper cable with an N male on one end and pl259 on the other? Would it be necessary to calibrate the RigExpert with SO239 standards (short, open, load) first, or will the effects of the short (under a foot long) jumper be noticeable?
At the end, you said 7.1 J of inductance. Was that a verbal typo? I misheard it while going down other mental roads with antennas?
It could have been, thanks Frank!
Given a 50 Ω transmission line matched to a resonant and radiating antenna; can the antenna be thought as acting as an impedance matching device to space impedance 377 Ω ?
You would need a trans match between the transmission line and the antenna 👍
I find it both interesting and curious no one thinks of an antenna as an impedance matching (w/ transmatch).
@@thomassecurename3152 it’s because you will get the reflection at the feed-point, if you add the trans match it’s handles the reflection for you
@@TheSmokinApe Thank you. fm W7TOM
The only use of a multimeter in antennas is as a continuity tester to check for open or shorts.
Agreed. You’d be surprised at how many time I’ve seen “experts” claim to be measuring impedance with a multi 👀
Just a quick point.
There's no such thing as making an antenna electrically longer or electrically shorter without physically making it longer or shorter.
If you look at that half wave 35ft 40m dipole, your "impedance" will read somewhere in the neighborhood of 73 +j0. Great. We may have a 1.5:1 SWR. No biggie, right?
If we add inductors in series of the dipole elements, we will bring the resonance down but the radiation resistance stays the same because you can't electrically lengthen the antenna without physically lengthening the antenna. The R value changes with a physical element length change but the R value doesn't have much change with the additional series inductance.
Therefore, you can take like a 58 foot flat top dipole and that R value is now pretty close to 50 ohms at 40m. See where I'm going with this? Yep. Now you can add a couple of inductors near the feed point to cancel the high capacitive reactance and voila, now have a ...
1. Short Dipole
2. SWR near 1:1.
You talk about the R value, but I'm not really hearing you say that this is what our hobby is all about. That's where our antenna current does its magic and radiation takes place.
Put some feeling into it. Yay!!!
He.. shed some light.. i see what u did there
Lol, thanks for watching 👍
Including the idea that impedance is the resistance to CHANGE vs merely the flow of electricity would help.
Thanks for the feedback Allen 👍
So I’ve gone down this rabbit hole of antenna tuning. I mounted a Laird NMO27 10-11 meter base loaded whip antenna on my truck for CB. I borrowed an MFJ analyzer from a friend and tuned the SWR as low as I could on the center freq. Under 1.8 across the band.. But my Impedance scale was as low as 20 ohm.. But it’s a 50 ohm load, with a 50 ohm coax. (RG58/u). I assumed maybe the Velocity factor was causing the low impedance. So I tried adding a couple jumpers just for test readings to no avail. . I haven’t encountered this issue before. I even grounded the antenna bracket with 1” ground strap to the hood. No effect. Anyone have any hints? Thank you for your time.
With AC current antennas will react differently with varying frequency. Impedance is made up resistance AND reactance, reactance is inductive or capacitive in nature. Have to attempted to adjust the length of the antenna?
@@TheSmokinApe Thanks for the reply. Much appreciated. The only tuning I have done to the whip was during the initial sweep with the analyzer. It is honestly kinda narrow banded. So I trimmed it to reach the lowest overall SWR on the 40 channel spectrum.
I know Z can mean impedence. But most people use the cap Greek letter Omega for these equations. Plus the Italic for other letters. The equation is a one off, but keeping with what we see in the ARRL, textbooks, might keep confusion down
Otherwise, great vid.
Thanks for the comment Dominic. So what I have seen we use Z to represent the word "Impedance" in formulas and we use the Omega sign to mean Ohms or the unit of measurement. Similar to how folks use I to represent current but the unit is Amps. That said I have seen more than one naming convention. Glad you liked the video!
SWR measures characteristic impedance versus load impedance?
SWR measured the delta between forward and reflected power 👍
@@TheSmokinApe isn't the ideal zero difference?
Yes, they call that a 1:1 ratio
I was doing fine until you got to the NanoVNA portion and then lost me. I trust everything you say Ape but I need to learn to make my own mistakes I guess, lol!
Great video as ALWAYS!
Todd WH6DWF 🇺🇸🇺🇸🇺🇸
Everyone is like that around the VNA at first, thanks for watching Todd!
The nanovna is easy to use and there are numerous good videos on them.
They are not a bench quality vna but still a very accurate tool.
You can do a heck of a lot more with them than you can with an ordinary antenna analyzer
In short video , you cover lot.some lines are very important ,that "swr dip is in left ,it means antenaa length is longer and need to tream" actualy i was searching like this type of video that can actualy tune antenna using smith chart.most people make typical video in smith chart just like a college professor where student never understand 😀
Thanks Victor, glad to hear it was helpful.
A lot of people become obsessed with trying to get a perfect tune on their antenna. Most antennas are a compromise. You can get close but never perfect. As soon as you change frequency things change. I always say horse shoes and hand grenades. Get it close and don't worry about it. Just have fun. Informative video.
Totally agree, thanks for watching Marvin 👍
I own a NanoVNA. I still have not mastered it.
Howdy Blue. Here is my playlist for NanoVNAs, it should help you out. The more you use it the better you will get with it. NanoVNA Playlist
th-cam.com/play/PLm8ROkpFeqornjIRLKS0RJqSrUl_lr5lv.html
None of those circles are concentric. None of them. None of them share a center. Not one.
SWR means nothing but an indication of power transfer from feedline to a dipole !!! Does other Hams hear you ??? Then the antenna WORKS ! Anything less than a 3:1 SWR is an efficient power transfer to the radiating elements. END DISCUSSION.
I admire your convictions...
Ape splainin at its finest.
Lol, thanks LC 👍🍻
Great explanation, would love to see one on smith charts!
To much yak, not enough facts....get to the point.
You'd still miss it...
I want to email you sending some screen shoto if vna smith chart of my SlimJim and need to ask some questions.if you didn't mind,can u have your email id please?
Sure. thesmokinape@gmail.com