FM Microwave Radio Receiver Components Quiz

The channel-combining network is used to connect multiple microwave transmitters to a single transmission line feeding the antenna.

The channel separation network in the FM microwave receiver isolates and filters individual microwave channels to direct them to their respective receivers.

The FM demodulator in the FM microwave receiver is a coherent detector.

Typical distances between an FM microwave transmitter and its associated microwave receiver are between 5 miles and 15 miles.

A single-hop microwave system, such as the one shown in Figure 2, is adequate for most practical system applications.

The bandpass filter, AM mixer, and microwave oscillator in the FM microwave receiver down-convert the RF microwave frequencies to IF frequencies and pass them on to the FM demodulator.

For frequencies above 30 MHz to 50 MHz, the surface wave is considered the most important path.

At frequencies above 30 MHz to 50 MHz, the sky wave is a reliable signal for microwave communications purposes.

The free-space path loss involves dissipation of energy along the propagation path.

The free-space path loss is calculated based on the absorption or reflection of energy from nearby objects.

Surface and sky wave propagations are the main focus in the chapter on microwave communications.

The free-space path loss includes elements like transmit antenna gain and receiving antenna gain.

The noise figure of the mixer down-converter in the receiver is 10 dB.

The total input noise power of the microwave receiver is -102 dBm.

The path loss for a frequency of 200 MHz and a distance of 800 km is 0.5.

The fade margin for a 30-km microwave hop with a reliability objective of 99.995% is 20 dB.

For a system gain of 114 dB, the minimum input C/N is 34 dB.

The terrain sensitivity loss for an 8-GHz carrier over very smooth and dry terrain is negligible.

The minimum carrier-to-noise ratio at the receiver input is 30 dB.

The overall noise figure for a receiver with two RF amplifiers, a mixer down-converter, and IF gain is 18 dB.

The microwave receiver has an overall noise figure of 6 dB.

The system gain is 126.8 dBm.

The minimum receive carrier power for a minimum C/N ratio of 20 dB at the input to the FM detector is 73 dBm.

The free-space path loss is 141.8 dB.

The transmission path should pass over obstacles with a clearance of at least 0.6 times the distance of the first Fresnel zone.

Refraction effects necessitate greater clearance to reduce deep fading under adverse atmospheric conditions.

To determine the height of a microwave tower, a profile plot of the terrain between the proposed antenna sites is made.

The worst obstacle in the path, such as a mountain peak or ridge, is ignored when determining the minimum path clearance.

Portable antennas, transmitters, and receivers are used to test the location to determine the optimum antenna heights.

Path loss remains constant over time, and the receive signal level can be calculated to within 1 dB for path lengths above 10 GHz.