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Quadrifilar Helix Antenna

Posted 24 mar 2017, 10:45 GMT-4 RF & Microwave Engineering Version 5.2, Version 5.2a 5 Replies

Sebastian Thuné
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Hi!

I'm looking to simulate a Quadrifilar Helix Antenna with infinite balun and was hoping that some one either: Done it before or knows how to do it.

I have built a model in comsol as seen in the picture. I've put the arms, inner conductor and the outer conductor as "Perfect electric conductor" boundary. in the bottom of the center coax cable i've put the boundary between the inner and outer conductor as a "lumped port". I have a far field boundary as seen in the pictures. The outer boundary of the Far field sphere is put to a "Scattering boundary condition"

All domains ar set to air and the the arms and conductors are in copper, the dielectric in the coax is PTFE with epsilon_r = 2.1.

The mesh is set to minimum wavelength of 0.2*wavelength.

When I simulate it, it never seem to converge and ran for a hour on one freq. Thats when i gave up and started thinking that I have done something wrong. I've only done RF simulations for a week and will take any help/lesson I can get and will appreciate it immensely.


Thanks,

Sebastian
5 Replies Last Post 24 ago 2017, 02:13 GMT-4
Edgar J. Kaiser Certified Consultant
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Posted: 8 years ago 24 mar 2017, 11:16 GMT-4
Sebastian,

Comsol mostly chooses an iterative solver as default in RF models. Try a direct solver if you have enough memory.
If you can upload the model we can have a closer look.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Sebastian, Comsol mostly chooses an iterative solver as default in RF models. Try a direct solver if you have enough memory. If you can upload the model we can have a closer look. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Sebastian Thuné
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Posted: 8 years ago 27 mar 2017, 04:13 GMT-4
Hi Edgar,

Thanks for the answer. I will try the direct solver instead.
For some reason the webpage does not let me upload the model file so I put it on Dropbox instead under the link:

www.dropbox.com/s/mfd9hllg0jp1pcx/QuadrifilarHelixantenna.mph?dl=0

Hopefully that will work for you guys.

Again, all feedback in any form is welcomed.

Regards,

Sebastian
Hi Edgar, Thanks for the answer. I will try the direct solver instead. For some reason the webpage does not let me upload the model file so I put it on Dropbox instead under the link: https://www.dropbox.com/s/mfd9hllg0jp1pcx/QuadrifilarHelixantenna.mph?dl=0 Hopefully that will work for you guys. Again, all feedback in any form is welcomed. Regards, Sebastian
Edgar J. Kaiser Certified Consultant
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Posted: 8 years ago 27 mar 2017, 09:09 GMT-4
Sebastian,

a quick look into your model revealed that some metallic boundaries around the feed into the helices are not properly assigned. You may want to check that.

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Sebastian, a quick look into your model revealed that some metallic boundaries around the feed into the helices are not properly assigned. You may want to check that. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Sebastian Thuné
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Posted: 8 years ago 3 apr 2017, 05:13 GMT-4
I'll have a look. Thanks!
I'll have a look. Thanks!
Asif Al Noor
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Posted: 7 years ago 24 ago 2017, 02:13 GMT-4
Hi Sebastian,

Have you figured out the mistake in your simulation file? If yes, could you please update the file that you shared. It would be very helpful if I could use your model for my research.

Thanks.
Hi Sebastian, Have you figured out the mistake in your simulation file? If yes, could you please update the file that you shared. It would be very helpful if I could use your model for my research. Thanks.

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