Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Microstrip Coupled line filter design using Rogers Ro4003

Status
Not open for further replies.
R

ramin.ala

Junior Member level 1
Joined
Dec 13, 2010
Messages
19
Helped
7
Reputation
14
Reaction score
7
Trophy points
1,283
Location
!
Activity points
1,429
Hi everyone

I have designed a coupled-line filter at X-band using Ro-4003 with 8mil of thickness.

Rogers Software (MWI-2016) suggests dielectric constant of 3.81 for this substrate, this thickness, and at X band. this number has significant difference with popular dielectric constant for RF design using RO4003 (I mean 3.55).

What is your suggection? should I use 3.55 in my design (and expect shift in response!) OR use 3.81 and be optimistic!
 

I'd suggest using 3.55 until proven otherwise. When working with a board material that I'm not familiar with, I also make a 50 ohm line to verify my trace width. Sometimes this 50 ohm line can be chopped from the input or output trace and connectorizing this. 4003 is quite common.
 
Recently I asked PCB fabrication house about RO4003 and was surprised by this fact. They have recommended Er values for design (without stating frequency, only thickness) , while still providing standard Er value of RO4003. Why still providing standard value? Is it frequency and thickness dependent value?
 

Er is related (to some extend) on a number of factors. I would expect that John Coonrod @ RogersCorp could do an all day discussion on this topic.
h**ps://www.rogerscorp.com/documents/726/acm/RO4000-Laminates---Data-sheet.pdf
The above data sheet shows Er (Dk) vs Frequency. Design engineers have to start with some number to select substrate and thickness... and keep track of assumptions. I do mostly octave and multi-octave designs.
 

ramin.ala said:
Hi everyone

I have designed a coupled-line filter at X-band using Ro-4003 with 8mil of thickness.

Rogers Software (MWI-2016) suggests dielectric constant of 3.81 for this substrate, this thickness, and at X band. this number has significant difference with popular dielectric constant for RF design using RO4003 (I mean 3.55).

What is your suggection? should I use 3.55 in my design (and expect shift in response!) OR use 3.81 and be optimistic!
Click to expand...

I haven't tried the MWI-2016 version yet, but using MWI-2014 at 10GHz, the software provided a frequency related Er value of approx 3.7 for RO4003 of 12mil thickness and the filter centering was pretty good.
 
edf said:
I haven't tried the MWI-2016 version yet, but using MWI-2014 at 10GHz, the software provided a frequency related Er value of approx 3.7 for RO4003 of 12mil thickness and the filter centering was pretty good.
Click to expand...

Thank you.
This answer is what exactly I looked for (experience with dielectric constant, suggested by MWI).

Another question is about non-isotropic dielectric constant of RO4003 (it shows slightly different dielectric constant in X, Y, and Z directions). Therefore, its dielectric constant may also be depend on structure that is printed on substrate.

Is it correct?

It it possible to define a non-isotropic substrate (as mentioned above) in HFSS (or CST)?
 

ramin.ala said:
Thank you.
This answer is what exactly I looked for (experience with dielectric constant, suggested by MWI).

Another question is about non-isotropic dielectric constant of RO4003 (it shows slightly different dielectric constant in X, Y, and Z directions). Therefore, its dielectric constant may also be depend on structure that is printed on substrate.

Is it correct?

It it possible to define a non-isotropic substrate (as mentioned above) in HFSS (or CST)?
Click to expand...

I've only had trial exposure to HFSS and CST. I did use the Er value from MWI for my full-wave EM simulation in AWR's Microwave Office.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top