From: Doug McKean (firstname.lastname@example.org)
Date: Mon Sep 25 2000 - 09:17:46 PDT
"KHOO,KENG-KOK (HP-Singapore,ex4)" wrote:
> Sorry for the mistake.
> The box demension is (L)70mm x (W)120mm x (H)140mm
Your actual problem may be as Mr. Weir explained.
The various modes of TE resonance for those dimensions
will give you the following frequencies:
It operates on the fact that the length of one of the
dimensions is one half wavelength for resonance. So, the
1.25 GHz comes from a resonance along the 120mm width.
The length is considered half wavelength because it
sets up a standing wave. The 1.07 GHz comes from a
resonance along 140mm height. The 2.14 GHz comes from
a resonance along the 70mm length. Again, the actual
lengths being considered half wavelengths.
Assume for the moment that various combinations of the
(height, width, depth) are different resonance modes at
a fundamental frequency. It's easy to assign numbers
so that (1,0,0) is the fundamental resonance along the
height (between the top and bottom plates), or
1,0,0 = 1.07 GHz.
Likewise, the other modes turn out to be ...
0,1,0 = 1.25 GHz (TE resonance between the side plates)
0,0,1 = 2.14 GHz (TE resonance between the front and back plates).
The other modes
1,1,0 = 1.64 GHz
1,0,1 = 2.48 GHz
0,1,1 = 2.39 GHz
1,1,1 = 2.70 GHz
are more complex modes of resonance. 1,1,0 being a resonance
between the top, bottom, and side plates, etc ...
The calculation of these frequencies is simply
by using the three dimensional distance formula.
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