This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: 37 Effective area and reciprocity Antenna response to multiple plane waves: Consider next an arbitrary antenna located at the origin with x y R z a resistive termination R , a gain function G ( , ) , and Incoherent power addition : Consider a voltage v ( t ) = V 1 cos( t ) + V 2 cos( t + ) applied across a 1 resistor where is a random phase shift param eter. Squaring v ( t ) and taking its timeaverage it can be shown that the time averagepower P = 1 T T v 2 ( t ) dt = 1 2 V 2 1 + 1 2 V 2 2 + V 1 V 2 cos( ) . Notice the third term in P . With random we would be unable to know P , but still its expected value is P = 1 2 V 2 1 + 1 2 V 2 2 , which is the incoherent sum of the timeaverage power due to signals 1 and 2 oneatatime . which is exposed to a spectrum of incident plane wave fields E i at a frequency f = 2 arriving from directions ( i , i ) with power densities S i , such that each E i arriving from ( i , i ) is polarized identically as the field the antenna would radiate toward direction ( i , i ) . Assume that each plane wave E i will deliver an average power P r = S i A ( i , i ) to the resistor R oneatatime where A ( , ) is by definition the effective area of the antenna for reception and, furthermore, the...
View Full
Document
 Fall '08
 Staff
 Electromagnet

Click to edit the document details