Coaxial Waveguide Cutoff Frequencies

does anybody know how to find these using MATLAB? apparently there are special formulas or something that each waveguide has to be able to calculate the kc's for each q'nm mode. i don't understand this at all.

There is an old, venerable reference I find particularly useful:

Principals and Applications of Waveguide Transmissions, Southworth

i kind of need to know now. i have something due pretty soon and i've been clueless about this problem for 12 hours now. i have no bloody idea how to find these things.

The basic relations can be found in any HF engineers handbook, I think.

The fomula is not avaialbe in most of the books.

Here is the formula for cutoff frequency for TE11 mode

f=c/ (0.5*pi*(b+a)*Sqrt(√εμ))
c=speed of light
a=inner radius of the coax
b=outer radius of the coax

Regards

Coaxial Waveguide propogate TEM mode . so it cutoff frequency is infinity.

I think Coax surely support TE11 mode as frequency increases

its pure TEM mode

yes coax support pure TEM mode before cuttoff at higher frquency TE11 mode is also supported and obvously not desired