1. Collin, R. E., Foundations for Microwave Engineering, John Wiley & Sons, 2007.
2. Pozar, D. M., Microwave Engineering, John Wiley & Sons, 2011.
3. Fooks, E. H. and R. A. Zakarevicius, Microwave Engineering Using Microstrip Circuits, Prentice-Hall, Inc., 1990.
4. Rao, P., Design of Wide Band Hybrid Coupler, LAP LAMBERT Academic Publishing, 2013.
5. Maddio, S., G. Pelosi, M. Righini, and S. Selleri, "Balanaced loaded transmission lines applied to hybrid couplers design," 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 947-948, IEEE, 2018.
doi:10.1109/APUSNCURSINRSM.2018.8608400 Google Scholar
6. Maddio, S., G. Pelosi, M. Righini, and S. Selleri, "A novel hybrid coupler design based on the concept of balanced loaded transmission lines," 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, 743-744, IEEE, 2019.
doi:10.1109/APUSNCURSINRSM.2019.8889137 Google Scholar
7. Cidronali, A., S. Maddio, N. Giovannelli, and G. Collodi, "Frequency analysis and multiline implementation of compensated impedance inverter for wideband doherty high-power amplifier design," IEEE Transactions on Microwave Theory and Techniques, Vol. 64, No. 5, 1359-1372, 2016.
doi:10.1109/TMTT.2016.2549524 Google Scholar
8. Maddio, S., G. Pelosi, M. Righini, and S. Selleri, "A multi-objective invasive weed optimization for broad band sequential rotation networks," 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 955-956, IEEE, 2018.
doi:10.1109/APUSNCURSINRSM.2018.8608713 Google Scholar
9. Liu, G.-Q., L.-S. Wu, and W.-Y. Yin, "A compact microstrip rat-race coupler with modified lange and T-shaped arms," Progress In Electromagnetics Research, Vol. 115, 509-523, 2011.
doi:10.2528/PIER11032003 Google Scholar
10. Liu, H., S.-J. Fang, Z. Wang, and Y. Zhou, "Miniaturization of trans-directional coupled line couplers using series inductors," Progress In Electromagnetics Research C, Vol. 46, 171-177, 2014.
doi:10.2528/PIERC13122201 Google Scholar
11. Bernardi, P., R. Cicchetti, G. Pelosi, A. Reatti, S. Selleri, and M. Tatini, "An equivalent circuit for EMI prediction in printed circuit boards featuring a straight-to-bent microstrip line coupling," Progress In Electromagnetics Research B, Vol. 5, 107-118, 2008.
doi:10.2528/PIERB08020502 Google Scholar
12. Selleri, S., M. Mussetta, P. Pirinoli, R. E. Zich, and L. Matekovits, "Some insight over new variations of the particle swarm optimization method," IEEE Antennas and Wireless Propagation Letters, Vol. 5, 235-238, 2006.
doi:10.1109/LAWP.2006.874071 Google Scholar
13. Tseng, C.-H. and H.-J. Chen, "Compact rat-race coupler using shunt-stub-based artificial transmission lines," IEEE Microwave and Wireless Components Letters, Vol. 18, No. 11, 734-736, 2008.
doi:10.1109/LMWC.2008.2005225 Google Scholar
14. Agastra, E., G. Pelosi, S. Selleri, and R. Taddei, "Multiobjective optimization techniques," Wiley Encyclopedia of Electrical and Electronics Engineering, 1-29, 2014. Google Scholar
15. Agastra, E., G. Pelosi, S. Selleri, and R. Taddei, "Taguchi's method for multi-objective optimization problems," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 23, No. 3, 357-366, 2013.
doi:10.1002/mmce.20680 Google Scholar
16. Pelosi, G., S. Selleri, and R. Taddei, "A novel multiobjective Taguchi's optimization technique for multibeam array synthesis," Microwave and Optical Technology Letters, Vol. 55, No. 8, 1836-1840, 2013.
doi:10.1002/mop.27705 Google Scholar
17. Maddio, S., G. Pelosi, M. Righini, and S. Selleri, "A comparison between grey wolf and invasive weed optimizations applied to microstrip filters," 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, 1033-1034, IEEE, 2019.
doi:10.1109/APUSNCURSINRSM.2019.8888446 Google Scholar
18. Chuang, M.-L., "Miniaturized ring coupler of arbitrary reduced size," IEEE Microwave and Wireless Components Letters, Vol. 15, No. 1, 16-18, 2005.
doi:10.1109/LMWC.2004.840960 Google Scholar
19. Mandal, M. K. and S. Sanyal, "Reduced-length rat-race couplers," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 12, 2593-2598, 2007.
doi:10.1109/TMTT.2007.910058 Google Scholar
20. Gu, J. and X. Sun, "Miniaturization and harmonic suppression rat-race coupler using C-SCMRC resonators with distributive equivalent circuit," IEEE Microwave and Wireless Components Letters, Vol. 15, No. 12, 880-882, 2005.
doi:10.1109/LMWC.2005.859980 Google Scholar
21. Okabe, H., C. Caloz, and T. Itoh, "A compact enhanced-bandwidth hybrid ring using an artificial lumped-element left-handed transmission-line section," IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 3, 798-804, 2004.
doi:10.1109/TMTT.2004.823541 Google Scholar
22. Eccleston, K. W. and S. H. Ong, "Compact planar microstripline branch-line and rat-race couplers," IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 10, 2119-2125, 2003.
doi:10.1109/TMTT.2003.817442 Google Scholar
23. Settaluri, R. K., G. Sundberg, A. Weisshaar, and V. Tripathi, "Compact folded line rat-race hybrid couplers," IEEE Microwave and Guided Wave Letters, Vol. 10, No. 2, 61-63, 2000.
doi:10.1109/75.843101 Google Scholar
24. Kuo, J.-T., J.-S. Wu, and Y.-C. Chiou, "Miniaturized rat race coupler with suppression of spurious passband," IEEE Microwave and Wireless Components Letters, Vol. 17, No. 1, 46-48, 2007.
doi:10.1109/LMWC.2006.887254 Google Scholar
25. Chen, C.-C. and C.-K. Tzuang, "Synthetic quasi-tem meandered transmission lines for compacted microwave integrated circuits," IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 6, 1637-1647, 2004.
doi:10.1109/TMTT.2004.828468 Google Scholar
26. Monti, G. and L. Tarricone, "Reduced-size broadband CRLH-ATL rat-race coupler," 2006 European Microwave Conference, 125-128, IEEE, 2006.
doi:10.1109/EUMC.2006.281216 Google Scholar
27. Ghali, H. and T. A. Moselhy, "Miniaturized fractal rat-race, branch-line, and coupled-line hybrids," IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 11, 2513-2520, 2004.
doi:10.1109/TMTT.2004.837154 Google Scholar
28. Wang, C.-W., T.-G. Ma, and C.-F. Yang, "A new planar articial transmission line and its applications to a miniaturized butler matrix," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 12, 2792-2801, 2007.
doi:10.1109/TMTT.2007.909474 Google Scholar
29. Maddio, S., A. Cidronali, M. Passaume, G. Collodi, and S. Maurri, "Fine-grained azimuthal direction of arrival estimation using received signal strengths," Electronics Letters, Vol. 53, No. 10, 687-689, 2017.
doi:10.1049/el.2017.0456 Google Scholar