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Dipole antenna input impedance vs frequency

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randy orton

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Hello all

If I am plotting a graph for Input impedance vs frequency graph for dipole antenna using HFSS version 11. than how can i check that plot is correct or not?i mean my design is accurate or not?

One thing that i know is as following:

When the imaginary part of input impedance crosses 0 at that time the real value should be 75ohms.

Is it correct?and moreover is there any other ways to check the plot is accurate or not?

thQs in advance
 

streamlet

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75-ohm cannot serve as the gauge to verify your simulation results, since it is estimated theoretically by itself.

Beside simulation, there are other two approaches we can take advantage to reveal the truth -- theoretical calculation and measurement. There are what u can rely on to test your simulation results.
 

randy orton

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Hey streamlet

from the attached file can you say that is it correct or not?instead of 73 ohms i am getting around 117 ohms in the plot. so can you give some advise? or any opinion on that?
 

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FvM

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randy,

this is at least the third thread, where you are posting effectively the same question. Did you ever hear of forum rules about cross-posting?
 

randy orton

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Dear FvM

I am just looking for an answer that what I am doing is right or wrong?if it is right than why is it and if it is wrong than what i can do to improve my results? it looks like it is wrong so from experts like you i need some kind of guidance which can help me to solve problem. I am aware of cross posting but i just need some answers nothing else is my intention. i really dont want to increase traffic on forum, but the thing is i tried what ever knowledge i have, now i need some expert help from you guys.

Still i am sorry.
 

FvM

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The bad thing with cross postings isn't increasing traffic, but confusing discussions. For me, it's definitely a reason to keep away from some threads.

There may be cases where you are maintaining threads with partly different partly overlapping topic. That's not a problem so far. But there's no reason to start a new same topic thread shortly after two posts.

You can be rather sure that experts interested to help are scanning the respective forums according to their free time. You rather draw interest by telling a single clear, informative question than by swamping various forums.
 

RF_Jim

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The bad thing with cross postings isn't increasing traffic, but confusing discussions. For me, it's definitely a reason to keep away from some threads.

There may be cases where you are maintaining threads with partly different partly overlapping topic. That's not a problem so far. But there's no reason to start a new same topic thread shortly after two posts.

You can be rather sure that experts interested to help are scanning the respective forums according to their free time. You rather draw interest by telling a single clear, informative question than by swamping various forums.
I have to agree; some of us don't have a whole lot of time to read (and reply) on what look like somewhat 'redundant' posts ... to: randy orton, write clearly, put in as much necessary detail as possible (don't overdo it either!) and be assured that someone will answer at some point. Sometimes job or class or real life takes precedence for our time though!

BTW, I make out the 'resonant' frequency of your dipole from your plot at about 138 MHz and the Re component as 70 some Ohms, and I have 'cut' (and swept) my fair share of real dipoles in real life and those values look reasonable.

The one thing that would be good to do is if we could look at HFSS file, but, I see no reason for that at the moment (your dipole Z plots look reasonable for a dipole if it was intended to be 'cut' for around 138 MHz).

Jim
 
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