How to inerpret the input impedance from Smith chart whether it is perfectly matched over the frequency range ?
This is very basic question, to measure the input impedance using smith chart. As you know, if you have load impedance and characteristics impedance which is taken as 50 ohm, you can find out the value of Zin. You have to normalized the ZL by Zo and then plot real part on real axis (constant resistance circles) and after that, plot imaginary part on constant reactance circles. Where they cut to each other that is your Zin. To match Zin with ZL, first you have to match ZL=Zo and then Zo=Zin, which is matched conditions for transmission apart from open and short circuit condition, if you are not getting matching condition, use stub matching in which lambda/4 is the perfect one.
To calculate bandwidth, first plot S11 vs frequency and then take two peak points for that particular plot and measure the distance which decides your bandwidth of antenna.
Thanks
SM (impedance), on a software simulator (or a VNA if on the test bench) directly writes on the SM when you power the antenna system with a range of frequencies ( say start and stop) , under both these situation (software simulation or under testing) just move the cursor over the path traced, this will directly read the impedance associated with eaxh of the frequencies - across the complete band , which is the input impedance of that antenna system under design or testing at that spot-frequency wherever you have position the cursor - at the moment
as far as the BW is concerned, switch the plot attributes to RL (return-loss or VSWR) mode (in software or testing on VNA) whereever the plot-trace crossing value lies between 1:2 (VSWR) or -9.98 db and plot-trace returning back and crossing 9,98 db (if ever its crossing this mark) its the antenna system BW
You can use Smith Chart for Interpret of antenna's characteristics such as input impedance. The center of Smith Chart represent 50 Ohm impedance. If the loop of curve is occurred the near of center, you can understand that the impedance matching is occurred. In this link letter, the Smith Chart is used to Interpret bandwidth from Smith Chart.
http://www.freepaperdownload.us/1752/Article4987791.htm
Interesting question, in a way; pray tell us your field of study, Amit.
thankyou all
@Denis Jaisson: Communication Systems
Project on: "Antenna System Development for Microwave Imaging for Breast Cancer Detection"
I see... Then I suggest that you take courses on antenna theory and microwave circuits; otherwise you will be running in circle and shooting in the dark, I'm afraid.
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