×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Frequency selective surfaces

## Frequency selective surfaces

(OP)
Is anyone out there working on Frequency selective surfaces?
It seems I have a problem with TE polarization when reaching cut-off frequency

### RE: Frequency selective surfaces

I have in the past worked on them. So, what's the real problem?
An FSS is part of a radome near an antenna that rejects certain frequencies (it can be put in the antenna too, but carefully), it's really just a filter implemented in the antenna, usually it's rolloff's are weak compared to normal circuit based filters. You use them to cut out interference on a budget, or for high power transmissions where discrete devices would blow up easily.
kchiggins.

### RE: Frequency selective surfaces

(OP)
Thank you, Higgler,
You're right, those are some of the applications for the FSS's. What I am doing is a code to analyse them and when the element is a square or a symmetrical cross, and the unit cell is square, I should get the same reflection coefficient for both TE and TM polarization, but I don’t, and it seems that my problem is in the TE polarization and it worsen when I am approaching to its cut-off frequency.
Any idea?
Thank you very much.

### RE: Frequency selective surfaces

On boresight it should be the same, off angle it's very different, even though you're using square pieces. Maybe you have simple approximations that lose their luster at cutoff.

as an example off boresight, the impedance of a thick slab of dielectric is n/cos(theta) versus n*cos(theta)for the two different cases, and the thick slab is homogeneous.
Maybe you are doing it correctly.
kch
There are reference materials on them.

### RE: Frequency selective surfaces

(OP)
I'm just working on boresight by the moment.
Maybe, there's something with the condition number of the matrix. I've seen that the variations in this number along the frequency have influence in the final TE reflection result.  I'll keep working on it.

Thank you again

### RE: Frequency selective surfaces

Have you found the edge on performance of any square tic to be direction insensitive?

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!