10-10] 



TRANSMISSION LINES AND MODES OF PROPAGATION 



535 



The high temperature problem for supersonic missile radomes has 

 hastened the introduction of a new class of structural ceramics called 

 Pyroceram by Corning Glass. This material is unlike glass in that it is 

 crystalline and about twice as elastic as glass. Its hardness and softening 

 temperatures correspond more to those of stainless steel, whereas its 

 density is closer to that of aluminum. Its flexural strength is two-thirds 

 that of steel. Electrically, its loss factor is good and its dielectric constant 

 is 6. This dielectric constant is about midway between those of most of 

 the organic plastic radome materials and of some of the ceramics that have 

 been considered. As this is not one particular material, but rather a class 

 of materials, it is to be expected that as time goes on, compositions suitable 

 for a wide range of radome applications will be found. 



10-10 INTRODUCTION TO TRANSMISSION LINES AND 

 MODES OF PROPAGATION 



Any physical separation of the RF units of a radar, such as that between 

 the antenna and the transmitter, requires the use of an RF transmission 

 line to convey the electromagnetic energy in an essentially lossless and 

 radiation-free manner. Often more than one type of transmission line is 

 employed in a single radar to achieve most effective design. Selection of 

 Coaxial Strip 



(a) 



(d) 



Fig. 10-11 Cross Sections of Various Transmission Lines, Showing Electric Field 



Configurations for (a) Coaxial, (b) Strip, (c) TEio, (d) TE20, (e) TEu, (f) TMoi 



Modes, and (g) TEoi Modes. 



