I have designed a frequency reconfigurable antenna. When I change frequency to check multibands the previous resonating frequency changes. eg. freq sweep is 1-2 GHZ resonating frequency is 1.6GHz when sweep is changed resonating frequency also changes to 1.75GHz and the gain is also affected rather lowered. No, I have not changed solution frequency, just the sweep is varied. Why this is happening? Would it affect when I fabricate and test the Antenna? how should I overcome the problem?
Rohit,
In HFSS make use of discreet sweep type. Keep the start and stop frequency in which you are interested. Keep the solution frequency as maximum frequency in start and stop frequencies. This will give you correct results.
The point you are saying about changing resonant frequency is due to change in number of meshes due to change in solution frequency, sweep type and range of frequencies.
Rohit,
Always follow standard settings in simulation software. The guidelines will be available in the software guidelines brochure. You have not mentioned the type of simulator you are using. The software settings depend upon the type of software you are using....
Anveshkumar Nella ,
I am using HFSS and antenna is designed in Driven Modal. Well did not find any guideline what sweep is supposed to be alway. Thanks.
Rohit,
In HFSS make use of discreet sweep type. Keep the start and stop frequency in which you are interested. Keep the solution frequency as maximum frequency in start and stop frequencies. This will give you correct results.
The point you are saying about changing resonant frequency is due to change in number of meshes due to change in solution frequency, sweep type and range of frequencies.
Anveshkumar Nella,
Thanks a lot for the suggestion, I'll keep in my mind. But still one question remains, Would fabricated results will match or reach close to simulated results? I know quality of fabrication is also important to match the results. What else can be done to get matched results of simulation and measured? Thanks once again! :)
Rohit,
They almost close to simulated ones provided standard simulation and fabrication precautions....
Try to keep discrete mode analysis and high no.of passes such as 10 for better result. Also check whether your result is converged or not.
Thanks.
Ravi Dwivedi, well, Antenna is converging, the RL, gain, pattern are good. just that changing sweep also changes resonating frequency with a small margin 1.63 Ghz to 1.635 GHz. Will try simulation with discrete mode, Thanks for suggestion.
Before manufacturing and to have a matched results to the measured ones, you need to update the accuracy and convergence setting, for example, max_delta to be 0.005 instead of 0.02 and passes 10 instead of 6 then discrete sweep with a small step such as 10MHz.
What may be happening and change fr from 1.6GHz to 1.75GHz if you have a different step with changing the sweep so different points are simulating, which can come from putting a number of point in the sweep instead of a fixed step. But if you fix the step and all other parameters such as solution frequency, you must have the same results.
Kerlos Atia Abdalmalak,
Thanks for the suggestions. solution frequency is same, so is step size, linear count with 201 and max_delta was 0.02. The only change I made was change is sweep earlier it was 1-2GHz then to check multibands I made 1-4 GHz. The change in Resonating freq I got was 1.6GHz to 1.635GHz. Which made me concern about manufacturing, as it may affect the result quality.
I will try with delta value 0.005. Thanks once again.
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