350lect38 - 38 Equivalent circuit models of coupled anten-...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 38 Equivalent circuit models of coupled anten- nas Since Maxwells equations and the associated boundary conditions which govern the interaction of a pair of antennas with input currents I 1 , 2 and response voltages V 1 , 2 are linear , the equivalent circuit model describ- ing the relationships of I 1 , 2 and V 1 , 2 is also linear and obeys a set of equations +- +- I 1 I 2 V 1 V 2 r +- +- I 1 I 2 V 1 V 2 Linear 2-Port V 1 = Z 1 I 1 + Z 12 I 2 V 2 = Z 21 I 1 + Z 2 I 2 Ant.1 Ant.2 V 1 = Z 1 I 1 + Z 12 I 2 V 2 = Z 21 I 1 + Z 2 I 2 . With I 2 set to zero, we recognize Z 1 above as the input impedance of ant.-1, while Z 21 is a coupling impedance connecting the open circuit response voltage of ant.2 to the driver current of ant.1. Likewise, Z 2 is the input impedance of ant.2 and Z 12 is a coupling impedance from ant.2 to ant.1. The reciprocal behaviour of a pair of antennas separated in free space restricts the coupling impedances in the model circuit to satisfy Z 21 V 2 I 1 | I 2 =0 = Z 12 V 1 I 2 | I 1 =0 Z c so that transmission gain P t /P r is independent of the transmission and reception roles assigned to the antennas (as verified below). 1 With that restriction the equivalent circuit model of the coupling sim- plifies as (see margin) Reciprocal circuit model for antenna coupling: +- +- V 1 V 2 I 1 I 2 Z c Z...
View Full Document

Page1 / 6

350lect38 - 38 Equivalent circuit models of coupled anten-...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online