Calculate the ratio horizon for a 500-ft transmitting

Question

Part A:

1. A balanced transmission line picks up an undesired signal with a 5mW level. After coversion to an unbalanced signal using a center-tapped transformer, the undesired signal is 0.11 µW. Calculate the common mode rejection ratio, CMRR.

2. A fast rise-time 10-V step voltage is applied to a 50-Ω line terminated with an 80-Ω resistive load. Determine the reflection coefficient Γ, E_F and E_r.

3. Calculate the ratio horizon for a 500-ft transmitting antenna and a receiving antenna of 20ft. Calculate the required height increase for the receiving antenna if a 10% increase in the radio horizon were required.

4. An antenna has maximum forward gain of 14dB at its 108-MHz center frequency. Its reverse gain is -8dB. Its bandwidth extends from 55 to 185 MHz , calculate a) the bandwidth and b) the F/B ratio of the antenna.

5. Calculate the effective radiated power (ERP) of an antenna with a gain of 5 at a power of 0.5 kW.

6. The antenna in question 5 has a forward gain of 18dB and a reverse gain of 5dB, calculate the F/B ratio of this antenna.

7. A ship radio-telephone transmitter operates at 2738 kHz. At a distant point from the transmitter, the 2738 kHz signal has a measured field of 147 mV/m. the second harmonic field at the same point is measured as 405 µV/m. How much has the harmonic emission been attenuated below the 2738 kHz fundamental?

8. Calculate the maximum usable range for a radar system with PRT of 400 µs.

9. A green LED light source functions at a frequency of 5.7 * 10¹⁴ Hz, calculate its wavelength.

Part B:

1. A signal level of 0.4 µV is measured on the input to a satellite receiver. Express this voltage in terms of dBµV. Assume a 50-Ω system.

2. A microwave transmitter typically requires a +8dBm audio level to fully drive the input. If a +10dBm level measured, what is the actual voltage level measured? Assume a 600-Ω system.

3. If an impedance matched amplifier has a power gain (P_OUT/P_IN) of 15, what is the value of the voltage gain (V_OUT/V_IN)?

4. Determine the deviation ratio for an FM system that has maximum possible deviation of 5 kHz and the maximum input frequency is 3 kHz. Is this narrow-or wideband FM?

5. A receiver with a 10 MHz bandwidth has a S/N of 5dB and a sensitivity of -96dBm.

6. What is the dynamic range (in dB) for a 12-bit PCM system?

7. Calculate the number of bits required to satisfy a dynamic range of 48dB.

8. The transmit power for digital communications device is 1W. The data rate is 28.8kbps. Determine the energy per bit.

9. A 56kbps NRZ-L encoded data stream is used in a digital communication link. Determine the minimum bandwidth required for the communications link.

Answer 1

For the following questions illustrated below, answer the following questions by providing the appropriate concepts. Q1. A balanced transmission line picks up the undesired signal by means of a 5mW level. After conversion to the unbalanced signal employing a center-tapped transformer, the undesired signal is 0.11 µW. Compute the common mode rejection ratio. Q2. A fast rise-time 10-V step voltage is implemented to a 50-O line terminated by means of an 80-O resistive load. Find out the reflection coefficient G, EF and Er. Q3. Compute the ratio horizon for a 500-ft transmitting antenna and a receiving antenna of 20ft. Compute the required height raise for the receiving antenna if a 10% raise in the radio horizon were needed. Q4. The antenna consists of maximum forward gain of 14dB at its 108-MHz center frequency. The reverse gain is -8dB. Its bandwidth expands from 55 to 185 MHz; compute a) bandwidth and b) F/B ratio of the antenna.