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how to read gain in polar plot (hfss v13)?

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silky khurana

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i have simulated a aperture coupled patch antenna. the plot of gain is intersecting the axis near 0db. I want to know, what does it mean actually? can anybody plz tell me how to analyze the graph?
 

gain its a measure you have to perform where the radiated fields of your structure are strong, having this in mind, the radiated fields of most microstrip patch antennas happen broad side ( normal to the patch), in HFSS you plot gain in dB ( with out normalizing), if your antenna has 0dB it means that it doesn't have any gain in that particular direction, usually you need 0dB gain in all directions for a wrap around antenna, plus G= efficiency x Directivity, so either you have a low directional antenna, or you have a high loss antenna .
 
Have you looked at the 3d gain plot? Perhaps this helps for the understanding of the polar plot, especially with the used coordinate system.
Also it is good to look at the directivity plot.
 

this is the 3D polar plot.. plz tell me if i have taken the right coordinate systems?(theta and phi) if not then what is the criteria? another fig is the gain vs theta... is it correct?
gain and theta.jpgpolar.jpg
 

I don't understand your 3D polar plot
I assume the following :
the antenna is flat in the X Y plane
the slot is pointing in the z direction
In polar coordinates the R parameter will be the gain ; maximum occurs at theta = 90 deg
The phi plane beam should be symmetrical ; this parameter is call the azimuth for radar
The theta plane is also called the elevation in radar
See the following URL for some pictures https://www.google.com/search?q=3d+...uMMuIhQfNw_CnBw&ved=0CDUQsAQ&biw=1252&bih=556
 

How do you have generated the plot?
 

your 3d plot is strange. i think value of theta and phi for far filed are
theta:-180-180 step size=2
phi:0-360 step size=2

this will show better plot.
you can also plot gain vs frequency same as s parameter plot in hfss in far field report.
 

Hello!

I have designed a slotted patch antenna (+ superstrate) and i need to find the peak value of gain. I have also created a far fields 3d polar plot {db(GainTotal)} and it seams ok, but my questions is: what is the range of values that i sould see? Is there a rule??

Plz help!
Thanks
 

8the range of values are half power Beam width (HPBW), so first you should seek where its the maximum gain of your design ( usually where the retrn loss is minimum for frecuency and for microstrip antennas the "place on the radiation pattern " its usually broad side Theta = 0° Phi=0°), then you plot a 2d radiation pattern of gain at that frecuency the cuts should be Phi=0 to 90 with increments of 90 degrees and theta=0 to 180 with increments of 1 degrees, you subtract 3dB of your maximum gain and look where the lines cross this values and measure the beam width usually its about 60 to 90 degrees. hope this helps.
 
Thank you Dfmona for the information, but my question was more about the peak gain value (and in general the expected values of gain). I seem to get a very low value of peak gain....

My antenna is a compact microstrip, with a substrate of 0.65mm thickness and material with εr=9. I can't change these values...
Except for the use of a superstrate is there anything else i can do??
 

I did MIMO antenna .I got -20 return loss.My doubt is in MIMO antennas how much isloation is needed? and also how to calculate isloation between the antenna?and i attached the gain plot how to analysis this plot?
 

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Hello vishwanivi,
please open a new topic for your question.
 

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