Problem 4 (10 points) (Chap 3) (Learning objective: Wave Propagation in TEM transmission line) A voltage wave Voe- travels along a transmission line. The voltage is maximum at = x/4 and t = 0. The wavelength A is 10 cm. Write an expression for this voltage wave as a function of both position and time. Be sure to indicate numerical values in your solution whereever possible.

3) Solve the cutoff frequency for the first mode and second mode of WR975 Wave guide TABLE 7.1 Some Standard Rectangular Waveguides Waveguide de signation a (in) b (in) t (in) fe, (GHz) Frequency range (GHz) WR975 9.750 4.875 0.125 0.605 0.75-1.12 WR650 6.500 3.250 0.080 0.908 1.12–1.70 WR430 4.300 2.150 0.080 1.375 1.70-2.60 WR284 2.840 1.340 0.080 2.08 2.60-3.95 WR187 1.872 0.872 0.064 3.16 3.95-5.85 WR137 1.372 0.622 0.064 4.29 5.85-8.20 WR90 0.900 0.450 0.050 6.56 8.2–12.4 WR62 0.622 0.311 0.040 9.49 12.4–18

Solve the cutoff frequency for the first mode and third mode of WR430 waveguide.

Communication system

We have discussed in class that a wire should be treated as a transmission line when its length exceeds an appreciable fraction of the wavelength. If this fraction is 1%, calculate the maximum frequencies at which you can neglect the transmission line effects for the following (assume the wave velocity is equal to speed of light in free space) and make the comparisons indicated: a. Power line of length 300 km (How does this frequency compare with the line frequency used for AC power?) b. Phone line of length 3 km c. USB cable of length 0.3 m (How does this compare with today's USB data rates?) d. CMOS circuit trace of length 300 μm (How does this compare with today's processor frequencies?)

Answer the following questions with simple answer within few lines only. A. If the probability of error of BPSK is 0.85 then Pe of BFSK is? B. What happens to the radio wave propagation when the refractive index of ionospheric layer becomes low or high? C. If the number of quantization levels are multiplied by four time them how many numbers of bits are added to the actual number? D. What is the disadvantage of wave tilt? E. What is a bipolar line coding technique with phase encoding, and explain why it is named as phase encoding method? F. What is oblique communication circuit? G. What are the differences between DPCM and Delta Modulation? H. What is the change in bandwidth when channel capacity is doubled and two number of bits are increased?

Give a waveguide example that can support a TEM wave.

1- 2- 3- 4- 5- s, True or False, and correct the error if there is. The solid-state relay depends on the electric field to control the output moving parts. At the solar cells, the long wavelengths generate electron-hole pairs at near the surface. The IMPATT is a noisy system because it depends on the avalanche break down. The BARITT diode depends on thermionic emission rather than avalanche multiplication. For IMPATT and BARITT microwave devices, the frequency generation is inversely proportional to the drift region length. 6- The Gun diode depends on the avalanche break down.

Ope X. The frequency spectrum of an AM signal is shown below: 5.5V 1V 1V 52kHz 58kHz a) if the modulating signal is a sine wave, write the equation of the modulating signal b) if the carrier signal is a cosine wave, write the equation of the carrier signal c) calculate the current of the AM signal flowing through a 300-ohm load

Q/ The wave impedance of the TE10 mode of an air-filled rectangular waveguide at a frequency of 15 GHz is given to be 480 2. a- Calculate the cutoff frequency for the TE10 mode of this waveguide b- Calculate the 'a' dimension for the waveguide c- Calculate the cutoff frequency for the TE11 mode for this waveguide assuming b-0.4a d- Calculate the wave impedance at the frequency of 15 GHz for the TE10 mode if the above waveguide is filled with a dielectric with &,-2.5