Understanding Radiation planes: - Page 1
Forum section: electronics / rf-microwave

author: Beamin
author_rank: Super Contributor
timestamp: October 29, 2018, 11:45:39 am
content: These charts always throw me off.I have added where I think the antenna would be in the pictures. Is this what it would look like? Also when you see these patterns they would extend out miles from the antenna?http://www.taoglas.com/wp-content/uploads/2015/04/AP.10E.07.0039B-1.pdf

author: tggzzz
author_rank: Super Contributor
timestamp: October 29, 2018, 12:00:18 pm
content: The antenna is in the centre.It is the far-field radiation pattern, so extends to infinity (unless something gets in the way). It is not valid close to the antenna, the near-field patterns are required there.FFI, use "near field" and "far field" search terms.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 29, 2018, 12:24:59 pm
content: this must be cool!

author: coppercone2
author_rank: Super Contributor
timestamp: October 29, 2018, 06:43:54 pm
content: I have seen a crude cheap machine for making them, it actually just used less then 1 wall with EMI-absorbing cones on it with a receiver antenna infront and spun the antenna around in a room, it was not full anechoic.

author: hagster
author_rank: Frequent Contributor
timestamp: October 29, 2018, 06:55:24 pm
content: Those plots look mislabled to me. The third plot is just the first two ploted on the same graph.Also. And this is the big one. They have measured them at the wrong frequency. 1624MHz is satcom not GPS.

author: rhb
author_rank: Super Contributor
timestamp: October 31, 2018, 02:55:25 pm
content: As this is a proper question for this forum, here are a some basic plots.The first and third are from "Antenna Theory and Design" by Stutzman and Thiele 3rd ed. They show the free space far field field patterns for dipoles of varying lengths.The second is from "Antenna Theory, Analysis and Design by Balanis 4th ed. It displays the 3D coordinate system typically used. Normally plots will show the XY plane and the XZ plane but for highly directional antennas, they will also show the YZ plane.The circles shown on the 3rd figure are the strength for a fictional isotropic point radiator.

author: Beamin
author_rank: Super Contributor
timestamp: January 10, 2019, 10:47:20 am
content: Quote from: rhb on October 31, 2018, 02:55:25 pmSo the antenna (the little thing that looks like an "i" that I drew in is not in the correct space on the first two?Its hard for me to visualize things if I have no reference but my mind only works in pictures so the concept won't make sense until I can picture it in my head.

author: rhb
author_rank: Super Contributor
timestamp: January 10, 2019, 03:43:50 pm
content: I provided an answer, but only because I happened to be reading those books at the time. That was over two months ago.Please do some research before posting questions. No one is obligated to answer your questions or try to sort out your badly drawn diagrams of things you don't understand.In short, your confusion is your problem and caused by your behavior. You are the only person who can correct the problem. And your general attitude suggests that is unlikely to happen. You have a very large ego inflated with a vast amount of hot air and very little, if any thought.There's an old proverb that the best response to a fool is silence. Because all responses produce the same result. You still claim to be "testosterone free" even though I pointed out that was not accurate. A fact that the most trivial internet search would have shown you.Buy yourself a copy of the ARRL handbook and read it. Any edition will do, so it won't cost much.

author: Beamin
author_rank: Super Contributor
timestamp: January 13, 2019, 04:47:40 am
content: Quote from: rhb on January 10, 2019, 03:43:50 pmYes, I know that women have 20-50 ng/dl of testosterone. I know exactly what level I am at: 18, so it was a joke, not to be taken as scientific fact. But if it's upsetting you I can add a disclaimer that its a joke or change it to my real levels but that kind of ruins it.Why the hatred and rudeness? As you said you can just ignore the question if you think its "stupid" but its kind of hard to google questions that for me are visual. When someone familiar with the concept can quickly say that's correct or incorrect. Lately I have been coming here after I google a question, not before like I was earlier, even though I always learn a lot more here and get more education from reading the posts vs search results. The intelligent conversation is what I like even if I'm only receiving it and not capable of reciprocating the knowledge. I never demanded that anyone answer my question nor made that indication. So I don't know why you seem to think I have a huge ego or more importantly why you feel the need to point that out. I have an opinion of many here but if it's not positive I have enough tact and humility to keep it to myself. There is an old American proverb that says "If you have nothing good to say you..." Well we don't need to go there. Chill. Its just a forum post.

author: BravoV
author_rank: Super Contributor
timestamp: January 13, 2019, 07:33:11 am
content: Quote from: Beamin on January 13, 2019, 04:47:40 amThere, see ? You just admitted it yourself, you just too ignorance to be aware of that how average people, not male nor female, reacts to spam in disguised right ?Just look at your own previous thread counts and the titles, to be frank, its more like testosterone thingy rather than spam to me, as my previous advice to you, talk to your boyfriend, a really serious talk or just dump him.You deserved better one rather than slowly degrading yourself here among strangers and foreigners.

author: rhb
author_rank: Super Contributor
timestamp: January 13, 2019, 02:44:58 pm
content: This is an electronics forum. Sexual identity is completely irrelevant. You started an entire thread devoted to the subject. In it you denigrated one group of males because they thought they knew more than you did and the other group of males because they were geeky nerds. In short, you have a crappy attitude towards men and are blaming it on the men when it is your fault. Before that thread I'd assumed you were just some idiot male whose posts I made a point of avoiding.Contrary to what many believe, the internet is *not* a substitute for a book. Nothing in any of your posts indicates any knowledge of electronics at all. Have you ever cited a book or paper you have read in one of your threads? Have you posted a circuit you have built? In short, you have not even demonstrated an *interest* in electronics. You don't appear to have any interest in any threads except the ones you start.Why do we find you annoying? Because this is a *very* high volume blog with thousands of posts a day. So if you do as I and I'm sure many others do, try to skim through all the active threads it can be rather daunting. If you've been away from the computer for a few days there will be in excess of 40 pages of posts since your last visit. I recently had to mark everything as read even though I had only made it through about 2/3 of the recent posts.I gave you a very precise answer with examples and references. Over two months later you want me to look at your crappy cartoon and explain to you what is wrong with it. Clearly you did not pay any attention to the answer for 2 months.You are *not* special. You are *not* entitled to anything. The only thing guaranteed in life is you will die. Everything else is a product of luck and hard work.As I and others have pointed out before, you are just posting personal "look at me" spam without a shred of content actually relevant to electronics.The only reason I posted my answer was the hope that you had gotten enough of a shock to start behaving in a sensible manner.

author: coppercone2
author_rank: Super Contributor
timestamp: January 14, 2019, 08:49:45 pm
content: i think alot of literature on RF is garbage if you don't have a ridiculous mathematical background.I have experience with MV calculus, differential equations, physics, linear algebra and half of this stuff would require me to get textbooks I never seen before to attempt. I know where to look if I really wanted to figure some solutions out but its just not appealing to do so at all for fun/hobby. There is also a TON of untested theoretical stuff out there because no one can afford to buy the mathematician machine shop hours to test his work. Look for documents prior to like 1975 if you want to get the intuitive feel you are looking for. Otherwise you are going to get literally clobbered with math. The military is particularly useful at explaining antennas if you can find their researchers documents from navy lab etc.Some of the stuff I picked up at a university library that was more recent is like being stupid enough to open the mall doors in a zombie invasion. Just compare something like sedra smith to the art of electronics, with RF/plasma its much worse.The absolute worse shit (only rivaled by SOME books about DSP) is this tome I found about radars once. Oh man cool satellite dish on the cover, some stars, I thought 'damn they musta built some kind of cool radio astronomy van', I thought I would be dog earing that thing in a cafe.. I open it and I feel my eyes diverting and eventually bulging out of my head. Pages upon pages of surface integrals. Not a single picture of anything useful or practical, I could not even find a fucking sketch of something remotely useful. If it was called "boring ass addendum used to optimize cost sensitive radar designs that is useful between the years 1985-1988 and may summon evil spirits" I would have given it some credit. Instead it was called something like 'introduction to radars". To this way I wonder what the person looked like that would find it to be a introduction to radars. I know what they probably looked like, the greeks described this creature as a "gorgon".What you get in a old textbook, is less math nonsense optimization, and some examples of earlier experiments that help clarify. You just won't understand the process unless you got an idea of how they started developing that math. No engineer approached it from a rigid theoretical framework, they found one that fit eventually when they got some kind of peicewise model going (which is still useful to know).***Actually I will say, there is one beast that may be worse then the microwave books, this is the nuclear physics books. I found some shit written in German before (probably pulled out of the fuhers eagle castle) that blitzkreiged my fucking brain. The only interesting thing about it was that I learned they had a integral symbol on a special type writer. I was told there was only a few copies of those books in existence( for good reason). Yea thats right, I am pretty sure it was Nazi literature about reactors. Something like 1936. Despite being horrific on the eyes, there is the possibility the book was called something like "how to perform detailed calculation of nuclear subsystem xx5" (well known German specificity) rather then 'introduction to nuclear energy'. Double surface integralor something on the first freaking page. Believe it musta been un-touched for at least 50 years given how difficult it was to pry out of the book shelf and how glued it was to surrounded literature. It smelled bad and I always wondered what would happen if you approached it with a Geiger counter.**************************************************************************And to answer the OP question, what it looks like is the antenna is in the middle and there is a stationary sensor and the antenna rotates around at a fixed distance. The antenna wont orbit the sensor because thats too complicated to make a track its easier to put it on a swivel joint and spin it around. Like no one would do that because its a ridiculous amount of variables to addthey use this type of stuffhttps://www.pasternack.com/rf-rotary-joints-category.aspxthen the planes should be easy to imagine once you get the image of the setupYou don't want to move the cables around because they introduce flex-related phase error and they wear down (being made of foam dielectric typically for better cables), wheras the rotary joint comes with a manufacturers specification and it can be easily replaced.The EMI labs and even small room test stations with a single wall all come with a kind of turn table that has a controller which you can make it spin, and it has a signal that outputs the angle and you control its speed, they often put a wooden table on top of it.so you make a polar plot based on the angle the table sensor puts out and the signal (often just power) from the receiver antenna. You can go 3d polar if you add another rotary joint or some kind of universal joint and have it sweep.I made something like this out of a old hobby telescope mount, it spins in a circle and up and down a certain number of degrees and you program it with a little controller and it runs on 12V. Decent construction quality etc. Has a camera screw on the bottom to mount to a decent tripod and the base is fly-cut aluminum for flatness.If you are testing antenna polarity you also want to be able to tilt the antenna on another axis. You can also use a actuator to move the height of the antenna around if you get it high up in the air (think like a basketball hoop) rather then try to tilt it.you can add another rotary platform to rotate the antenna but then you need more joints, and it might be cheaper, easier and more stable to make the receiver rotate rather then giving the antenna a rotational axis along its major axis (where it radiates the most energy if its directional, like the face of a horn).Those 3d plots are mostly the same shit as the projects that you see about turning a hand-held IR laser thermometer into a REALLY SLOW thermal imaging camera, but keep the phase in mind (meaning you need to rotate it 360 degrees at all measurement points).https://hackaday.com/2011/03/09/arduino-thermo-cam/but instead of reflection back into the transmitter, imagine the laser as a flashlight that moves around at every possible angle relative to the sensor and backfeeds its position.The confusing part might be the receiver, but keep in mind it has its own profile (you can imagine it for simplicity as a camera lens with a specific FOV), and you measure that FOV constantly, you are not measuring a single point. If you have a 15 degree FOV on the sensor (say the horn angle), and you rotate the antenna being measured by 1 degree, you are still measuring 15 degrees, so you can kinda think of a box-car filter like effect going on. You just get a magnitude.More advanced systems might measure it with a phased array or something, but its unlikely you will ever see this unless they are testing it with a AEGIS missile cruiser or F22 radar (supposedly). Everyone else just rotates shit mechanically.

author: dmills
author_rank: Super Contributor
timestamp: January 15, 2019, 12:23:32 am
content: Bet your book was actually something like "FUNDAMENTALSof radar", be very afraid of any academic book with that word anywhere on the front cover, it is academic speak for "Get yer math on if you think your 'ard enuf".But when you need to get the math on, you need to get the math on, and then those books are worth even Springers prices.AOE gets you to reasonably competent technician, you can read a datasheet and use the sand that someone else designed, and that is fine for a hobbyist or (the intended market!) the physics graduate student who needs to make their supervisors experiment dance, and you can go a long way with that. However if you really want to understand the details, then "Sedra Smith" is IMHO superior, as are things like "Fields and waves in communications electronics", and you will never really understand control theory or filter design without working thru some of those "Get yer math on" books.73 Dan.

author: coppercone2
author_rank: Super Contributor
timestamp: January 15, 2019, 01:07:51 am
content: i agree its a very broad overview but it gives you an idea of what the profession looks like a bit and you get a whole idea. If you are not studying EE for half a decade then you won't get much use out of just reading sedra smith, but you will get a great view from just reading AOE.I had to get an idea of what the industry looks like by talking to faculty that worked before and spending some free time getting lab tours and harassing professors etc. People here are just like 'read a book' but you can get SO tripped up doing that as a start. Unusable crap is dime a dozen, I was selling old DSP books out of the trash whole sale (people would rather throw them out then even keep them as a professional reference they were so bad). I have a feeling if you put that in your office in a company someone that actually knows the field would either think your some kind of super genius or a bullshitter if he saw it on your shelf, either losing respect for you or giving you insane labor.I would say in america though, even if you take all the classes, if you don't get lucky with ex-industry professors that like talking about it on the lectures or don't do some of your own investigations you won't have too much of an idea of WTF is going on. Then you can end up working and get super compartmentalized.And I don't know what the book was, maybe a introduction to being intimidated by paper, I put it back in real short order. Bad distant memory, made me feel like I wasted a few hours of my life but at least I can laugh about it now. I am telling you it was the most unreadable piece of shit I ever encountered. I read some fucking topology textbooks by Russian professors and some parts of 'mathematical analysis' by rudin and other normally considered to be atrocious reads and these engineering textbooks I mention take the cake in terms of being unreadable, boring, confusing and intimidating.Some low level (undergrad) organicish chemistry textbooks have some real garbage in them too. I was looking through a family members textbook recently then I saw a suspicious reaction. I spent 30 minutes on google and I found out how to do it, with like 8 missing steps and weird catalysts required. In theory, written in a research paper around 1986. If they did the textbook problem they would think some impossible ass shit is like mixing in a beaker friendly. When its like 8 percent yield with a completely different complicated mechanism with all these weird sub-steps required. It was like the topic of a PHD research paper not some intro chem reaction. The atoms just don't work the way they said.You need to be careful with books if you want to bring something to life, I don't think the questions posed in this thread are too bad. Its not like 'hur dur whats the volts mean' its a test result representation of a fairly complicated analysis involving moving parts, multiple axis, polar coordinates, radio frequencies, etc.some representation of results are just heinous. I saw some one diagram once, when I was young, that I could not figure out for the life of me. Like a 3d plot with all these lines (something to do with acid concentration, reaction rate, pressure, temperature ,etc). Criss cross apple sauce in the 3rd dimensionthis kinda comes to mind with confusing ways to present information, now imagine someone added some axis and lines to try to open up some fucked up rip in space time with it lol..

author: amyk
author_rank: Super Contributor
timestamp: January 15, 2019, 03:58:29 am
content: https://archive.org/details/principlesunderl00unitQuite old and discusses some truly obsolete technologies, but the laws of physics haven't changed. Chapter 4 should have what you're looking for, provided you actually take the time to read it carefully.If you look around the other threads here, you'll see the amount of knowledge others possess. That is because they learned, so respect that by doing some of your own learning before asking them. This has nothing to do with gender/sex/identity politics or whatever they call that crap these days, and everything to do with how you behave around others. This is not the place to be spoon-fed.