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IE3D port definition problem

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abhi_kolkata

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hi ,

can anybody plz suggest me how to feed(the port definition) a rectangular microstrip patch antenna (resonating at 30 GHz) with a microstrip inset feed line over finite ground and finite dielectric layer(about 0.35mm thick and of same size as the finite ground i.e. 15mmx15mm)in IE3D.i want to know how to define port for this antenna with finite ground and dielectric in IE3D correctly so that i can get highly accurate results.

plz do help me out.

with regards

abhi
 

Hi, Adhi:

Here are some models (edge fed, infinite gnd & sub, finite gnd &/or sub) for the 8 GHz range. You can start from them.

I do want to warn you on the substrate thickness. The 2nd order mode should happen at about 30 GHz for a 0.35 mm thick substrate. Even you can use edge fed, microstrip lines in this frequency range with such a thick substrate may have problem. You can consider reducing the substrate thickness for such a high frequency. Regards.
 

hi jian,

can u plz send the example files u mentioned in ur reply to my email addr.,so that i can download them and try them out.

i am working at this moment.

my email id : abhi_8051@yahoo.co.in and abhi_hrec1@yahoo.co.in

with regards
abhi

Added after 2 minutes:

hi jian,

can u plz send the example files u mentioned in ur reply to my email addr.,so that i can download them and try them out.

i am working at this moment.

my email id : abhi_8051@yahoo.co.in and abhi_hrec1@yahoo.co.in

with regards
abhi
 

Hi, Adhi: Just send them to you.
 

hi jian,

i am sending to u the geometry files that i have modelled for the 30 GHz antenna. plz let me know that they are not violating any of the IE3D modelling rules(or port assignment rules).Whether the antenna will give nearly same results - if i fabricate it on similar finite substrate & gnd (and if i try the same geometries with HFSS).

while doing the models i tried to stick to the procedure given in the examples sent by u.but if in any case i have made an mistake plz kindly let me know.

eagerly waiting for ur reply.

With regards

abhi
 

Hi, Abhi:

I will check it. Please remember that the thick substrate is not a rule of IE3D. It is a general one for any structures. I will get back to you soon. Thanks!

Regards.
 

hi jian,

i was designing a 30 GHz inset fed(width: 0.26mm) microstrip patch
antenna over 15x15 mm ground and 0.35mm thick
substrate of permittivity 12.9.
now, as u suggested me previously, i am trying to
simulate it on infinite gnd and substrate ,as that is
almost is the case here.
but while doing that and setting a port i.e.
port->port for edge group->advanced extension scheme(5
cells for deembeding arm)as mentioned in the IE3D
manual(chapter 5)and simulating it with meshing freq.
40 GHz and 20 cells/wavelength.it is giving a medium
warning that the substrate is too thick for this port.
is that a serious warning .if so, wat should i do??

plz do reply with ur valuable suggestions.

with regards
abhi
 

Hi, Abhi:

For 30 GHz (Er=12.9 from your file), the waveguide wavelength is about 3 mm. 15 by 15 mm ground plane is quite big already. I think you should use infinite ground plane for the modeling. Again, your substrate is 0.35 mm. The 2nd order mode should happen around 30 GHz. It is quite possible that some energy can get converted into the 2nd order mode from discontinuities. You may not be able to get very consistent results no matter from simulation or from measurement. You should try to reduce the substrate thickness if you want to have the antenna working very well at 30 GHz.

Best regards.
 

I think it's better to use a vertical feed in case of finite ground. The feeder will be defined inside the dielectric at the excitation point. The top of the vertical port will be connected to the radiating plate, the bottom will be connected to the finite ground.
 

Yes. Probe-feed should be more appropriate for such a thick substrate.
 

hi jian,

following ur line of advice , i'm now trying to simulate the same structure mentioned before using infinite gnd and infinite substrate(12.9) and i'm using a vertical localized port at the microstrip feed line edge( positive level = 0.0035 mm and negative level = 0 mm; for substrate thickness of 0.35mm). i have taken the length of the microstrip feed line(a 50 ohm line) 7.4274 mm to reflect the feed point impedance exactly at the port end.

plz let me know is this set up is valid.

with regards

abhi
 

Hi, Abhi: I got your e-mail. I will check it and see what exactly you try to do. Regards.
 

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