• Support PF! Buy your school textbooks, materials and every day products Here!

Calculate attenuation constant of an aperture

  • #1
31
0

Homework Statement


The shielding efficiency of an aperture depends on e−αd, where α is the frequency-dependent attenuation constant of the aperture and d is the thickness of the material (or the cutoff waveguide) at frequencies below cutoff.

2mxj4fq.png

where ωc=2πfc.

Calculate α for an air-vent (unshielded) of dimension 0.5×0.3×0.8 m3.

The solution given is

Cutoff frequency = 300MHz (cutoff wavelength = 1 m), α = 5.92

The Attempt at a Solution


I've tried to apply the formula above, with

ωc = 2π(300×106), μ (free space) = 4π×10−7, ϵ (free space) = 8.85×10−12, f = 100×106, fc = 300×106

But I get α = 37.25, not the value given. What am I missing?
 

Answers and Replies

  • #2
18,178
7,767
Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
 

Related Threads on Calculate attenuation constant of an aperture

  • Last Post
Replies
2
Views
2K
Replies
2
Views
4K
Replies
0
Views
1K
Replies
7
Views
6K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
0
Views
2K
  • Last Post
Replies
4
Views
2K
Replies
5
Views
3K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
0
Views
895
Top