tched to any number of receivers. This is true only within limits because the signal level supplied voltage transmission loss = (2.1.21) to individual receivers decreases with the number of distribution points. With large numbers of receivers, network losses become prohibitive. Transmission losses associated with the matching network of Figure 2.1-23 can be calculated by reference voltage transmission loss = 20 log[1/2n]dB18 to Figure 2.1-24. The network has been re-drawn for easier derivation of circuit losses but Z0, R and n still retain their original definitions. In Figure 2.1-24 Example 2.1.8 Voc = open-circuit source voltage from the aerial A broadcast signal induces an open-circuit voltage of Vce = terminated voltage at an intermediate point in 100 uV into a rod aerial. The aerial system has the network a characteristic impedance of 50 O and it is used to Vout terminated voltage at the input to a receiver supply signal to three identical receivers each of which has an input impedance of 50 Q. If the matching network type shown in Figure 2.1-23 is used, calculate (a) the value of the resistance (R) required for the matching network and (b) the ter- minated voltage appearing across the input terminals of the receiver. Given: 50 S aerial system, input impedance of each receiver = 50 S, no. of receivers = 3, open-circuit voltage in aerial =100 uV. Required: (a) Value of matching resistor, (b) termi- Fig. 2.1-24 Calculating the signal loss in an antenna distribution nated voltage at receiver input terminal. system. CHAPTER 2.1 Basic features of radio communication systems Solution Solution (a) For the matching network of Figure 2.1-23 By inspection: (b) Using Equation 2.1.20 (b) input impedance to the network V receiver = (43 + 75)/2=59 2 = = 16.67 uV 2.1.7.3 Other aerial distribution (c) receiver source impedance systems = 43 + + The matching network shown in Figure 2.1-23 is only one type of matching network. Figure 2.1-25 shows a com- mercially available matching network for two outlets. From the answers to 