The article is devoted to the development of a scheme of a dual-band transformer of complex load impedances into a given real value of the input resistance and to the method of calculating the electrical parameters of the elements in its composition. The proposed scheme consists of two segments of single lines, supplemented by a parallel branch on the input side. To remove restrictions on the possible values of complex impedances, which are generally different in different frequency bands, the circuit can be supplemented with two additional line sections, the parameters of which are chosen arbitrarily. It can be a section for connecting the load to the circuit, as well as a section in the form of a branch from the side of the load. Verification of the proposed transformer circuit was carried out by comparing the results of its computer simulation with known results.
[1] Wu Y., Y. Liu, S. Li. A dual-frequency transformer for complex impedances with two unequal sections // IEEE Microw. Wireless Compon. Lett., Feb. 2009, Vol. 19, No. 2, pp. 77–79. DOI:10.1109/LMWC.2008.2011315
[2] Liu X., Y. Liu, S. Li, F. Wu, and Y. Wu. A three-section dual-band transformer for frequency dependent complex load impedance // IEEE Microw. Wireless Compon. Lett., Oct. 2009, Vol. 19, No. 10, pp. 611–613. DOI:10.1109/LMWC.2009.2029732l
[3] Y. Wu, Y. Liu, S. Li, C. Yu, and X. Liu. A generalized dual-frequency transformer for two arbitrary complex frequency-dependent impedances // IEEE Microw. Wireless Compon. Lett., Dec. 2009, Vol. 19, No. 12, pp. 792–794. DOI:10.1109/LMWC.2009.2034034
[4] Y. Wu, W. Sun, S.-W. Leung, Y. Diao, and K.-H. Chan. A novel compact dual-frequency coupled-line transformer with simple analytical design equations for frequency-dependent complex load impedance // PIER, 2013, Vol. 134, pp. 47–62. DOI:10.2528/PIER12101906
[5] M. A. Nikravan and Z. Atlasbaf. T-section dual-band impedance transformer for frequency-dependent complex impedance loads // Electron. Lett., Apr. 2011, Vol. 47, No. 9, pp. 551–553. DOI: 10.1049/el.2010.7452
[6] M. A. Maktoomi, A. P. Yadav, M. S. Hashmi, F. M. Ghannouchi. Dual-frequency impedance matching networks based on two-section transmission line // IET Microw. Antennas Propag., 2017, Vol. 11 Iss. 10, pp. 1415-1423. https://doi.org/10.1049/iet-map.2016.0941
[7] Maktoomi M.A., Hashmi M.S., Ghannouchi F.M. A T-section dual-band matching network for frequency-dependent complex loads incorporating coupled line with DC-block property suitable for dual-band transistor amplifiers // Prog. Electromagn. Res. C, 2014, Vol. 54, pp. 75–84. DOI:10.2528/PIERC14090403
[8] R. K. Barik, P. K. Bishoyi, and S. S. Karthikeyan. Design of a novel dual-band impedance transformer // IEEE Intern. Confer. on Electronic, Computing and Communication Technologies (CONECCT-2015), 10-11 July 2015. DOI: 10.1109/CONECCT.2015.7383868
[9] Chuang, M.L. Dual-band impedance transformer using two-section shunt stubs // IEEE Trans. Microw. Theory Tech., May 2010, Vol. 58, No. 5, pp. 1257–1263. DOI:10.1109/TMTT.2010.2045560
[10] Y.-S. Lin , and C.-H. Wei. A novel miniature dual-band impedance matching network for frequency-dependent complex impedances // IEEE Trans. Microw. Theory Tech., Oct. 2020, Vol. 68, No. 10, pp. 4314–4326. DOI: 10.1109/TMTT.2020.3016328
[11] O. Manoochehri, A. Asoodeh, and K. Forooraghi. π-model dual-band impedance transformer for unequal complex impedance loads // IEEE Microw. Wireless Compon. Lett., Apr. 2015, Vol. 25, No. 4, pp. 238–240. DOI: 10.1109/LMWC.2015.2400933
[12] M. A. Maktoomi, M. S. Hashmi, and F. M. Ghannouchi. Improving load range of dual-band impedance matching networks using load-healing concept // IEEE Trans. Circuits Syst. II, Exp. Briefs, Feb. 2017, Vol. 64, No. 2, pp. 126–130. DOI 10.1109/TCSII.2016.2551547