2 a. Determine the scattering matrix of a lossless circulator (clockwise) that has insertion [5] loss of 1.5 dB and an isolation of 25 dB. b. Design a 5 dB Branch-line coupler for the system impedance of 50 Q and center [5] frequency of 5 GHz. Draw the top view microstrip layout of the coupler on substrate.

Problem 2 AConsider a cellular system of hexagonal structure. It is assumed that all the base stations transmit with the same power and the path loss follow the break-point model with exponent 4. The required S/I (signal power to interference power ratio) is 12dB. The fading margin is 10dB. What is the minimum cluster size?

Q6. Figure Q6 shows the line spectrum of a modulated signal (all components are positive and real). 3 1 232 234 236 238 frequency/kHz Figure Q6: Line spectrum of a modulated signal (a) Describe the modulation scheme. (b) What are the values of the carrier frequency, modulation frequency and the modulation index? (c) What is the transmission efficiency (ratio of modulated to total power) in this example? (d) The reception of this signal is undertaken with a superheterodyne detector using an intermediate frequency of 110 kHz. What is the appropriate local oscillator frequency? (e) Demodulation of this type of signal is usually accomplished using an envelope detector. Describe the principles of operation of an envelope detector and sketch an example circuit. (f) What considerations should be made about the component values in the design of an envelope detector in order to demodulate the signal after shifting to the intermediate frequency? Relative unitsS

4. For an AM DSBFC modulator with a carrier frequency fc = 100 kHz and a maximum modulating signal fm(max) = 5kHz, determine: a. Frequency limits for the upper and lower sidebands; b. Bandwidth; c. Upper and lower side frequencies produced when the modulating signal is a single frequency 3-kHz tone; Then d. Sketch the output frequency spectrum.

Q7. Figure Q7(a) shows the spectrum of a frequency modulated waveform with a sinusoidal modulation. 12 4.8 5.0 5.2 5.4 5.6 5.8 6.0 Frequency/MHz Figure Q7: (a) Spectrum of a frequency modulated waveform with a sinusoidal modulation. (a) Is this modulated waveform described as narrowband or as wideband? (b) What is the value of the carrier frequency? (c) What is the value of the modulation frequency? (d) Determine the value of the peak frequency deviation. Plots of Bessel functions of the first kind are provided below in Figure Q7(b) to assist you. (e) Estimate the fraction of the total signal power at the carrier frequency. (f) Detection of such a frequency modulated signal is usually accomplished with the use of a discriminator. Describe the function of a discriminator. (g) What is the equivalent AM modulation index obtained if this signal in Figure Q7(a) is demodulated with a high-pass RC filter discriminator? J„(x) 1.0 0.8 0.6 0.4 0.2 -0.2 -0.4 Figure Q7: (b) Bessel functions of the…

Identify how the excessive bandwidth use of FM can be overcome. (Check all that apply.) By using narrowband FM with small deviation ratios By using wideband FM with large deviation ratios By operating in the ultrahigh frequency (UHF) region By operating in the ultralow frequency (ULF) region By operating in the microwave region

In PM, as the amplitude of the modulating signal increases, the frequency deviation will ___________.    a. be infinite b. increase c. decrease d. be constant

What are the effects and significance of using filter capacitance?

3. The signal to noise ratio initially measured at the transmitter was 33 dB. The signal power was doubled prior to transmission in order to compensate the channel conditions. What is the new SNR at the transmitter?

answer b