ECSE_405___Simulation_Projects

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Jan 9, 2024

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ECSE 405: Antennas – Simulation Projects Instructor: Professor Milica Popovich (milica.popovich@mcgill.ca) TA: Milad Mokhtari (milad.mokhtari@mcgill.ca) October 2022 Please note the following teams and project assignments. All project descriptions are included in the subsequent pages. The guidelines for presentations and report formats will be given in a separate document. 1
ECSE 405: Antennas - Simulation Projects October 2022 Project I: Hansen-Woodyard Array of Dipole Antennas You are to design and simulate an endfire array of half-wave dipole antenna with Hansen-Woodyard excita- tion. The operation frequency is 1 GHz and a maximum gain of 12 dB in the + z direction is needed. (a) Based on the required maximum gain, specify the number of array elements, element spacing, their respective locations and Hansen-Woodyard phase shift. (b) Use MMANA-GAL to simulate and optimize a single element of the array. Report the radiation pattern, gain, VSWR and input impedance. Is the length of dipole exactly half the wavelength of operation? (c) Based on what you learned from (a) and (b) , construct the full array in the software and report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. What is the polarization of the assembled array? Also compare the side lobe levels to that of uniformly excited, equally spaced linear array. Discuss the trade-off between gain and side lobe level. (d) In the pursuit of improving front to back ratio of the array antenna, add a perfect ground plane to your configuration. Use the optimizer to find the optimum height between the array and the ground plane for maximum gain and front to back ratio. Once again, report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. 2
ECSE 405: Antennas - Simulation Projects October 2022 Project II: Yagi-Uda Antenna You are to design and simulate a Yagi-Uda antenna operating at 500 MHz with a main lobe in the + z direction. The maximum gain is desired to be more than 10 dB with front to back ratio also greater than 10 dB. Figure 1: Yagi-Uda Antenna (a) Briefly explain the role of the radiator, reflectors and directors. Discuss the effect of increasing the number of directors and reflectors on the radiation pattern. (b) Design a folded dipole antenna as the radiator. Report the radiation pattern, gain, VSWR and input impedance. What is the advantage of folded dipole over the regular half-wave dipole? Compare these two antennas. (c) Start with one director and one reflector (and of course one radiator) and simulate the antenna in MMANA-GAL . Try to increase the number of directors and reflectors to achieve the desired gain and front to back ratio. Use to optimizer to your advantage. For each step, report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. 3
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ECSE 405: Antennas - Simulation Projects October 2022 Project III: Log-Periodic Dipole Antenna You are to design and simulate a wideband wired log-periodic dipole antenna centered at 2 GHz with 2 GHz of bandwidth. The main beam is directed towards + z with maximum gain of 8 dB. Figure 2: Log-Periodic Dipole Antenna (a) Briefly discuss the reason why LPDA has a wide bandwidth. Talk about scale factor and spacing factor and their effect on the maximum gain. Why are the excitation line crisscrossed? (b) After carefully calculating the length of each dipole and their locations, use MMANA-GAL to simulate the antenna and report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. (c) Do a parameter study and the scale factor and spacing factor and their effect on the maximum gain and frequency response of the antenna. Thoroughly explain why increasing or decreasing the scale factor might result in less ripples in the frequency response. (d) Discuss the necessity of the load termination at the end of the antenna. Remove the load to see the effect. 4
ECSE 405: Antennas - Simulation Projects October 2022 Project IV: Cycloid Dipole Antenna You are to design and simulate a cycloid dipole antenna operating at 1 GHz and its required gamma matching network. The antenna should be matched to a frequency between 50 Ω and 200 Ω. You are permitted to approximate the circle with an octagon. Figure 3: Cycloid Dipole Antenna (a) Get yourself familiar with Cycloid dipole antenna here . This link and figure 6-35 from the Stutzman textbook can help you with the gamma match. Explain how this antenna radiates and what the polarization would be. Is it possible to achieve fully circular polarization? If yes, under what condition? (b) What is the role of the capacitor in the gamma match? How can one calculate its optimum value for a given antenna operating at a certain frequency? Discuss. (c) Design and simulate a 1 GHz cycloid dipole in MMANA-GAL and report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. Do this for both vertical and horizontal polarizations. 5
ECSE 405: Antennas - Simulation Projects October 2022 Project V: Square Loop Antenna You are to design and simulate a square loop antenna operating at 1 GHz and radiating towards + z direction. Figure 4: Square Loop Antenna (a) Discuss the operation mechanism and calculate the dimensions of the antenna by hand, using the analytical formulas. What is the polarization of this antenna? Why? (b) Design and simulate the antenna in MMANA-GAL and report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. (c) Plot the current densities on all wires. Discuss the current distribution. Study the role that the location of the excitation source plays. Report input impedance and VSWR for various locations of excitation. (d) In the pursuit of improving front to back ratio of the array antenna, add a perfect ground plane to your configuration. Use the optimizer to find the optimum height between the array and the ground plane for maximum gain and front to back ratio. Report your findings. (e) Use four of these antennas in a 2D array to improve maximum gain. report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. Do this for both vertical and horizontal polarizations. 6
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ECSE 405: Antennas - Simulation Projects October 2022 Project VI: Wire Biconical Antenna You are to design and simulate a wideband wire biconical antenna at 100 MHz with an omnidirectional pattern, matched to a 50 Ω impedance. Figure 5: Wire Biconical Antenna (a) Discuss why biconical antenna is widebanded and how we may approximate this antenna via a few tilted radial dipole antennas. (b) Simulate the antenna with different number of dipole antennas to find out about their effect on the performance of the antenna. Report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns for each. (c) Considering the size of the antenna, discuss whether it’s possible to increase broadside gain of the antenna via using an array. If it’s possible pair up four of these antenna together in a uniform linear array for a better gain. Report gain, VSWR, input impedance, front to back ratio, 2D and 3D radiation patterns. 7