parallel plate metal waveguide [Archive]

sarika

Oct7-04, 07:05 AM

Mikko Kiviranta

Oct8-04, 06:20 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nsarika wrote:\n> How can I obtain dispersion relation for parallel plate metal\n> waveguides with finite conductivity?\n\nYou can put a thin metal wall half the way between the\ntwo parallel plate conductors without affecting the field\npatterns. In this manner the parallel-plate waveguide\nreduces into two microstrip waveguides each having half the\ninsulator height. There is a large body of results for\nmicrostrip lines because of their importance in the electronics\nindustry: some of those can be found (with references\nto the original work) in the "Handbook of Microwave integrated\ncircuits" by Reinmut K. Hoffmann, and the "Transmission line\ndesign handbook" by Brian C. Wadell.\n\nI seem to recall that the dispersion relations are most\noften approximated to come due to the varying distribution\nof the fields into air and a material with higher dielctric\nconstant; *not* due to the conductor losses. If you cannot\nfind an explicit derivation of the dispersion relation due\nto conductor losses in the above references (but you may),\nperhaps you can modify the derivations in the literature\nand take the losses into account. Derivation of the propagation\nconstant (which includes the dispersion) for a general lossy\ntransmission line can be found e.g. in Pozar\'s\n"Microwave engineering".\n\nRegards,\nMikko\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>sarika wrote:
> How can I obtain dispersion relation for parallel plate metal
> waveguides with finite conductivity?

You can put a thin metal wall half the way between the
two parallel plate conductors without affecting the field
patterns. In this manner the parallel-plate waveguide
reduces into two microstrip waveguides each having half the
insulator height. There is a large body of results for
microstrip lines because of their importance in the electronics
industry: some of those can be found (with references
to the original work) in the "Handbook of Microwave integrated
circuits" by Reinmut K. Hoffmann, and the "Transmission line
design handbook" by Brian C. Wadell.

I seem to recall that the dispersion relations are most
often approximated to come due to the varying distribution
of the fields into air and a material with higher dielctric
constant; *not* due to the conductor losses. If you cannot
find an explicit derivation of the dispersion relation due
to conductor losses in the above references (but you may),
perhaps you can modify the derivations in the literature
and take the losses into account. Derivation of the propagation
constant (which includes the dispersion) for a general lossy
transmission line can be found e.g. in Pozar's
"Microwave engineering".

Regards,
Mikko