Problem 5.5. Noise Figure and Noise Power Output of a Multi-stage System The RF front-end of...

 

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Problem 5.5. Noise Figure and Noise Power Output of a Multi-stage System The RF front-end of a receiver, employed in a digital personal communication system, consists of an antenna, a low-noise amplifier, and a section of transmission line interconnecting the two. The antenna impedance, the transmission line characteristic impedance, and the receiver input impedance are all matched. The front-end is maintained at room temperature, and operates over a frequency range of 1805 to 1880 MHz. For a particular orientation and at a particular time, the antenna delivers a noise power of- 95 dBm over the operating bandwidth to a matched load at its terminals. The transmission line section causes a signal attenuation of 1.5 dB. The amplifier is specified by its manufacturer as having a power gain of 12 dB, and an equivalent noise temperature of 180 K for matched terminations at its ports. Determine the following: (a) The equivalent noise temperature of the antenna over the operating bandwidth. (b) The noise figure of the amplifier. (c) The noise figure of the chain consisting of transmission line in cascade with the amplifier. (d) The total noise power output of the front-end (i.e., the amplifier) over the operating bandwidth, delivered to a matched load. Problem 5.5. Noise Figure and Noise Power Output of a Multi-stage System The RF front-end of a receiver, employed in a digital personal communication system, consists of an antenna, a low-noise amplifier, and a section of transmission line interconnecting the two. The antenna impedance, the transmission line characteristic impedance, and the receiver input impedance are all matched. The front-end is maintained at room temperature, and operates over a frequency range of 1805 to 1880 MHz. For a particular orientation and at a particular time, the antenna delivers a noise power of- 95 dBm over the operating bandwidth to a matched load at its terminals. The transmission line section causes a signal attenuation of 1.5 dB. The amplifier is specified by its manufacturer as having a power gain of 12 dB, and an equivalent noise temperature of 180 K for matched terminations at its ports. Determine the following: (a) The equivalent noise temperature of the antenna over the operating bandwidth. (b) The noise figure of the amplifier. (c) The noise figure of the chain consisting of transmission line in cascade with the amplifier. (d) The total noise power output of the front-end (i.e., the amplifier) over the operating bandwidth, delivered to a matched load.

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a The equivalent noise temperature of the antenna over the operating bandwidth can ... View the full answer