Antenna Radiation Plots - Page 1
Forum section: electronics / rf-microwave

author: metrologist
author_rank: Super Contributor
timestamp: February 06, 2023, 04:23:15 pm
content: I have some test data and images of radiation plots from an antenna manufacturer. I tried plotting the data but my plot does not line up with their images. I'm wondering if my plots are incorrect? The data steps 2 degrees.E-Plane:-7.888590917-7.991426762-7.964447174-8.055839415-8.071694362-8.147931176-8.260241409-8.341474423-8.426699407-8.548298134-8.67139238-8.67490488-8.752658922-8.852553503-8.900487254-9.00316134-9.077233122-9.093310748-9.174045254-9.220654098-9.293490848-9.313394513-9.371693904-9.487061167-9.530401973-9.574138375-9.670540487-9.740592435-9.812144818-9.942311498-10.0231087-10.19606606-10.41928699-10.65396378-10.85331617-11.09422434-11.50908977-11.78147975-12.20503227-12.6067444-13.16966564-13.75408464-14.53368964-15.32319409-16.22802423-17.3506234-18.69167397-19.98061298-21.3475124-22.0921543-22.17379745-21.11051498-19.72278204-17.94414645-16.3585565-14.96053065-13.55272146-12.42186877-11.23678058-10.28379732-9.384124269-8.562270769-7.807099997-7.156599567-6.48212977-5.834852938-5.285693965-4.755729594-4.279265125-3.835901638-3.402162353-2.98161479-2.637312242-2.326132568-1.97821019-1.690502367-1.458851522-1.187267628-0.95572021-0.832346948-0.902673455-0.53869832-0.327827659-0.307425816-0.080693535-0.0126147620-0.053832101-0.03515279-0.021961633-0.011269447-0.00688131-0.032863242-0.104935266-0.287209137-0.461869844-0.46769158-0.658932299-0.83811115-1.099755593-1.309226083-1.682764918-1.991389725-2.228856793-2.49925663-2.849880381-3.061748849-3.371432041-3.969178052-4.383944758-4.770213989-5.229225957-5.761678062-6.275388761-6.859275072-7.442750791-8.069397557-8.684675392-9.369884107-10.05512583-10.76591077-11.52480213-12.37664169-13.16272559-14.08060253-15.07094322-15.95004176-17.17933236-18.20689739-19.57104888-20.41060611-22.07213948-24.03719576-25.70615388-27.72814505-30.03484659-30.58290624-30.04166738-28.66846112-26.58670704-24.79886898-23.36273108-21.82148713-20.61985291-19.36934675-18.44830622-17.4853645-16.78958131-15.96296761-15.20254271-14.68470777-14.08816028-13.49542668-12.99177124-12.50782458-12.01123076-11.65864276-11.1854634-10.89073254-10.46367354-10.23437747-9.864198535-9.615021897-9.401485169-9.155035464-8.966354894-8.75208112-8.609421715-8.471269356-8.318987282-8.188331398-8.035012643-7.986077082-7.98470578-7.957964855-7.870749283-7.843170677-7.779665174-7.838151379-7.884732798-7.886538485H-Plane:-34.12474937-33.94761734-31.68726194-29.01147271-27.00119113-26.18989902-26.26651224-26.45207089-26.66280019-26.18326016-26.16620094-26.46817391-26.81687665-26.98147921-26.96056868-26.8640185-26.31099053-25.76442834-26.30603607-27.73296402-26.80813566-23.9371756-22.50988079-22.40353494-22.27733849-21.5861555-21.33355453-20.7826906-20.01964965-20.55700425-23.26336948-23.17929264-20.08434423-18.0113634-16.78494926-17.24782763-19.88373045-18.69065855-15.83494526-16.1582191-18.65361732-17.71942159-15.82679879-15.76152372-16.61449507-15.99901296-13.83985078-12.80002144-13.03144362-13.17323193-12.3761371-11.64872938-11.24472774-10.61397746-9.530553022-8.4786042-7.935212371-7.629531081-7.08442738-6.413841022-5.777208975-5.360697228-5.17403264-5.058423751-4.688049588-4.218293156-3.959826862-4.058336164-4.179930801-4.030592562-3.68892579-3.431082434-3.439336504-3.482847901-3.355125047-2.99619726-2.579155674-2.185197609-1.880236855-1.58989397-1.358433775-1.170937165-1.040371651-0.856061176-0.693351923-0.475955121-0.282505432-0.141054838-0.0609301220-0.010957614-0.052525321-0.148082818-0.26249724-0.438543547-0.656521362-0.872980017-1.09570807-1.319149981-1.588191421-1.822906272-2.147848123-2.584932925-3.01938882-3.495039565-3.919970096-4.203219008-4.379055689-4.618152813-4.842536674-5.084213373-5.377986805-5.730449431-5.909225484-5.943224896-5.86374713-6.055059844-6.665822117-7.240094328-7.45660058-7.788540352-8.591182522-9.33975479-9.683607143-10.49760566-11.73614683-12.55493694-13.19178045-14.72326456-16.2604211-16.40599655-16.66292255-17.48925792-18.61801028-19.66542484-20.799605-21.63210884-22.06303023-23.55754771-25.68609775-24.8908343-24.14213744-24.07381293-23.40027338-23.55611005-25.51861171-30.20647588-33.44853371-31.73955289-31.99201338-31.8482976-29.60254114-29.31416088-33.1501321-36.77554554-30.88366371-28.42153097-28.68052773-30.30314107-32.70194725-35.62465642-39.53167966-44.42485969-37.91237143-33.65262058-30.82152635-29.61894301-28.76044969-28.3696369-28.18799428-27.97060522-28.29651233-29.14764236-30.03127911-31.09373437-32.52703335-34.9736113-37.09569996-36.88556916-35.11597151-34.35887698

author: joeqsmith
author_rank: Super Contributor
timestamp: February 07, 2023, 05:37:30 am
content: Quote from: metrologist on February 06, 2023, 04:23:15 pmYour post is vague. I am guessing the two plots you show are what the manufacture supplied along with the data below. You attempt to plot the data and suggest that you do not get the same results. You want to know if without you showing any of your work or your results if what you have is incorrect?If I plot it, I get something close to the graphs you show so I am going to assume the work you fail to show is incorrect. Am I correct?

author: fourfathom
author_rank: Super Contributor
timestamp: February 07, 2023, 07:14:29 am
content: Or are you wondering why your measured patterns don't agree with the published patterns? If so, there can be many reasons, and I would be quite surprised to see a perfect match.

author: metrologist
author_rank: Super Contributor
timestamp: February 07, 2023, 09:32:53 am
content: The plots shown are mine. Why would we not expect the results to be the same? It looks like Joe's plots are on a linear scale, but I am showing a log scale so of course that will not fit. I have both from the mfg. and have superimposed my plot and the mfg's linear plot onto Joe's. The e-plane point at 270 degrees should be ~-30dB, and I scaled them to make that point land on the 270deg line.Looking just at the h-plane data, if you look at the data and my plot, it seems like the point data falls in the correct place, but my plot reaches -infinity at the center. The mfg seems to scale theirs so the center is -50dB and Joe's at a wee bit less than -30dB.They also orient the e-plane data "pointing" to the left, but mark the left side 180 deg. Isn't it normal to start the elevation plot pointing to the right at 0 deg? I rotated my plot to make that so, but realize the plot data runs clockwise so I need to flip the trace to match the ccw scale.I also created a test plot with the top 90 deg starting at 0 dB and as rotating clockwise, each "notch" is -3, -10, -20, -30, -40, ... -80 dB, so it seems the data points land properly.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 07, 2023, 02:09:30 pm
content: So we have yet to see the plots supplied by the manufacture. Still the same problem, I have no idea how your plots compare with the manufacture's. It would be better if you supplied all of the details upfront.I am not understanding the emphasis of the angles, left, right and why you feel this matters.I wonder what your end goal is.

author: Bud
author_rank: Super Contributor
timestamp: February 07, 2023, 02:34:45 pm
content: The manufacturer's data is already Logarithmic log(A). You for some reason calculate log(log(A)) before you plot. That is why your plot is fatter on a same scale.

author: metrologist
author_rank: Super Contributor
timestamp: February 07, 2023, 05:57:04 pm
content: Quote from: joeqsmith on February 07, 2023, 02:09:30 pmThe mfg has other information in the graphics that are not for public release. I forgot to mention, in the image from Joe that I overlay my plot and the mfg plot, theredtrace is from the mfg. It is uniformly scaled to put the dips where they appear (or rather, so the outer normalized 0 value circles match in diameter.)But that does not matter because the center point value or axis range differs, as you can see. But then no matter how I scale the traces, they will never line up.And yes the data is log data but I am merely showing it on a log scale. The objective of course is to determine if my plot is accurately showing the data.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 07, 2023, 06:43:56 pm
content: I don't understand why you would care if you can plot data or not if the mfg is providing them. If you had told us that you wanted to run some calculations from that data then maybe it would have made more sense to me. Oh well.For the mfg's plots, maybe just remove the sensitive sections. Seems like you would rather focus on the plot I provided. So, I tried to make life a a little easier on you. Showing a single data set, larger graph with new scale scale. Maybe your mfg's data overlays this closer.

author: metrologist
author_rank: Super Contributor
timestamp: February 07, 2023, 11:33:57 pm
content: Sorry I was not very clear in my original post. I supplied my plots and just wanted to know if they are accurate to the data I also supplied. If not, then I'd have to go back and see if I could correct my error. I might need to ask for help to do that, though. So that is the question I am still wondering.Only to address some questions or curiosities:The plots they supplied are not usable for me for a variety of reasons. They are raster images and I really need vector image data that is in a versatile and more mainstream format for various applications. Say I want to publish them in a 4-color printing process and need to separate/trap CMYK colors. RGB raster images are not great for that. I also might want to target the plots to a variety of devices with various display requirements. Raster images with narrow lines do not scale very well. Also, perhaps they need to fit within a library of other similar type plots and would clash in their presentation. Also, not wanting to be dependent on mfg to supply the same in future...I already extracted the parts of the mfg image that is relevant and overlayed on other's plots here. The issue is they have overlayed about a dozen traces on the same plot, and those other traces are not relevant and overlap. You can see the broken trace that is available to me. Additionally, I have tabular measurement data to plot, and we would like to make our own measurements and plot in kind.Below is mfg plot on Joe's updated plot. I have so many plots of same data that look different. Which one is correct? Why are Joe's two plots so different?

author: joeqsmith
author_rank: Super Contributor
timestamp: February 08, 2023, 12:53:40 am
content: When I first glanced over your original post, I thought the same thing as fourfathom. Then I slowed down and read it ... Still confused but a little less...Plot scales are log vs linear. It just depends how you want to view the data. Assuming the manufacture knows what they are doing and have provided you with valid plots, the fact it overlays would seem to suggest you have your answer. Before jumping to any conclusions, if you would like to check the other data set, I have attached it.

author: metrologist
author_rank: Super Contributor
timestamp: February 08, 2023, 12:15:35 pm
content: Interesting. Joe's last plot on a log scale matches closely with the mfg plot on a linear scale. If I look at the data point that crosses 120 deg. it crosses the 0.500 circle. On Joe's first plot, it crosses just inside of the 0.400 circle (actually @ 300 deg. as the plot there is rotated 180). Which one is correct? What do these numbers mean? Is 0.500 -3dB? The actual data at this point is ~-6dB.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 08, 2023, 02:03:44 pm
content: Nice that it closely matches up. Because you can't provide the mfgs plots, I have no idea what units or scale factors they use to present their data. Again, there is no right or wrong. I am guessing based on what you have posted and what I have seen other manufacture's publish.If the plots that the mfg provided do not include details about the scaling, I would say that needs to be cleared up. It's odd that there is some error when you overlaid the mfg's data on what I show. I would expect these two to be identical. That discrepancy needs to be understood as well. Maybe the plot and the data are from two different sweeps, antennas, setups.... I think you will just need to work with them to get that sorted out. Time for a 10 minute phone. Guessing your under NDA so shouldn't be a problem.I would be interested in hearing what they have to say, assuming you're allowed to disclose it.

author: radiolistener
author_rank: Super Contributor
timestamp: February 11, 2023, 12:15:34 pm
content: Quote from: metrologist on February 06, 2023, 04:23:15 pmhow did you obtain test data? Antenna radiation pattern is very sensitive to any kind of object within near field region, antenna matching with a feeder and frequency.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 11, 2023, 04:10:17 pm
content: Quote from: radiolistener on February 11, 2023, 12:15:34 pmAs I understand it, they are just trying to plot the data supplied by the manufacture in the OP and have it match with the graph the manufacture supplied.

author: metrologist
author_rank: Super Contributor
timestamp: February 12, 2023, 11:13:01 am
content: Yeah, that's right. Something like thishttp://cuminglehman.com/wp-content/uploads/hf_lg2.jpg

author: joeqsmith
author_rank: Super Contributor
timestamp: February 12, 2023, 04:43:13 pm
content: Did you end up contacting the mfg to iron out the details?

author: metrologist
author_rank: Super Contributor
timestamp: February 12, 2023, 07:00:16 pm
content: I'm confident in my plot because of the test plot I posted above. All plots seem valid once considering the scale. I've even seen these plots on a rectilinear scale.The truth is, I made my Excel plotting capability about 10 years ago and could not remember how I did it. I can plot on log or linear scales and it seems fine.Pitiful MS does not have provision for polar plots in Excel natively.