e r m i t s a n i m p r o v e d c h a r a c t e r i s t i c r e s i s t a n c e o v e r t h e t r a n s m i s s i o n b a n d .No a d d i t i o n a l compon e n t s a r e r e q u i r e d t o p r o v i d e e s s e n t i a l l y f l a t t r a n s m i s s i o n bands From a u s e r ' s p o i n t o f v i e w , the p e r f o r m a n c e c h a r a c t e r i st i c s o f m o n o l i t h i c c r y s t a l f i l t e r s a r e v e r y s i m p l y s t a t e d i n t h e form ' B -' A ---2 x Ro; t h a t i s , t h e f r a c t i o n a l b a n d w i d t h i n ' m Hz/MHz i s a d i r e c t m u l t i p l e o f t h e t e r m i n a t i o n ' r e s i s t a n c e . A s p e c i f i c c a s e i s shown where a s i n g l e c r y s t a l p l a t e may be used t o form a m o n o l i t h i c f i l t e r t h a t may b e t e r m i n a t e d i n 100-ohm c i r c u i t s w i t h a r e s u l t i n g b a n d w i d t h o f .005$ o f t h e 'mean ' f r equency. T h i s m a y ' b e u s e d f o r a s i n g l e f r e q u e n c y s e l e c t o r s u c h a s c a r r i e r and p i l o t f i l t e r s i n t h e -r a n g e f r o m 6 t o 25 MHz o v e r n o r m a l c e n t r a l o f f i c e t e m p e r a t u r e r a n g e s . B a n d w i d t h s a s h i g h a s -07% may e a s i l y be r e a l i z e d w h i c h c a n a l l o w t h e u s e of s i n g l e s i d e band channel f i l t e r s a t c a r r i e r f r e q u e n c i e s a s low a s 6 MHz. Some e x a m p l e s o f t r a n s m i s s i o n c h a r a c t e r i s t i c s f o r m o n o l i t h i c c r y s t a l f i l t e r s a r e shown for narrow band and wide band cases a t a p p r o x i m a t e l y 10 MHz. O t h e r c o n v e n t i o n a l c r y s t a l f i l t e r s may be r e a l i z e d by t h e a d d i t i o n o f i n d u c t o r s a n d / o r c a p a c i t o r s w i t h i n t h e limits t h a t t h e e q u i v a l e n t l a t t i c e o f c r y s t a l u n i t s i m p o s e s . F i n a l l y , i t i s shown t h a t t h e g e n e r a l c a s e , f o r m o n o l i t h i c f i l t e r s o f t h i s t y p e , may b e c o n s i d e r e d a s a m e c h a n i c a l f i l t e r formed by e i a s t i c a l l y c o u p l e d r e s o n a t o r s and may be d e a l t w i t h b y c o n v e n t i o n a l t r a n s m i s s i o n m e t h o d s .200

At the high radio frequencies, filters and transformers become difficult to construct from conventional electrical coils and condensers, on account of the small sizes of the elements, the large effects of the interconnecting windings and the low ratios of reactance to resistance realizable in coils. It is shown in this paper that selective filters and wide‐band transformers can be constructed using transmission lines and condensers as elements. The ratio of reactance to resistance in these elements can be made very high; consequently very selective filters and transformers with small losses, can be constructed. The effect of the distributed nature of the elements is taken account of in the design equations and methods are described for obtaining single‐band filters and transformers. Experimental measurements of such filters and transformers are shown. The experimental loss curve is shown of a coaxial filter used in the Provincetown‐Green Harbor short‐wave radio circuit for the purpose of connecting a transmitter and receiver to the same antenna.

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