Chapter 5, Problem 129P

A cell phone antenna picks up a call. If the antenna and cell phone are modeled as shown in

Fig. P5.129,

(a) Find $R_{cell}$ for maximum output power.

(b) Determine the value of $P_{out}$.

(c) Determine the corresponding value of $P_{ant}.$

(d) Find $V_o/V_{ant}.$

(e) Determine the amount of power lost in $R_{ant}.$

(f) Calculate the efficiency $\eta =P_{out}/P_{ant}.$

(g) Determine the value of $R_{cell}$ such that the efficiency is 90%.

(h) Given the change in (g), what is the new value of $P_{ant}?$

(i) Given the change in (g), what is the new value of $P_{out}?$

(j) Comment on the results obtained in (i) and (b).