![]() ![]() ![]() The lumped elements circuit include DC-block capacitor, AC-block inductor, varactor diode and bias resistor. Tunable power dividers (TPD) are another category that controls the operating band or power-dividing ratio, using a circuit consisting of lumped elements and DC voltages. As a result, the power-dividing ratio can no longer be changed after the design and fabrication processes. In these PD type, the power division ratio can be adjusted arbitrarily during design process and before fabrication. To solve this problem, a Wilkinson and Gysel PDs with arbitrary power-dividing ratio are presented in 22, 23, 24, 25, 26, respectively. In the mentioned PDs, it is not possible to consider any value of power-dividing ratio. Because designs 19, 20, 21 use microstrip lines with unequal impedances without any resonator, they are suffering from large total size. ![]() One major disadvantage of 16, 17, 18 is large size. In 17, 18, a 1:6 unequal Gysel PD and a 1:10 UWPD are presented, respectively. A 1:5 UWPD is designed in 16 based on the offset double-sided parallel-strip lines. The UWPD with 1:4 power-dividing ratio 14, 15, which uses simple microstrip lines with different impedances, suffers from large size and inability to suppress unwanted harmonics. ![]() The power-dividing ratio is 1:3 in wideband, but return loss values are not proper in the working band. In 13, a structure using electromagnetic bandgap as a high-impedance transmission line (TL) is adopted for designing of UWPD. In 12, 13, the signal is divided into 1:2 ratio, but occupies very large size. Unequal WPD (UWPD) are another category for unequal signal division 12, 13, 14, 15, 16, 17, 18, 19, 20, 21. The second category is the PDs based on the narrow-band 5, 6, 7, dual-band 8 and wide-band BPF 9, 10, 11. But they are incapable of eliminating DC harmonics. To date, various types of WPD have been designed: The first category is PDs based on elliptic resonators and lowpass filters 3, 4, which are very good at suppressing harmonics up to high-order harmonics. The Wilkinson power dividers (WPD) are extensively used, with characteristics including: flexible power-dividing ratio, ability to remove DC, second and third harmonics, compact size, proper insertion and return losses, and good isolation between output ports. Besides, in microwave wireless communication systems such as phased arrays and beam-steering networks, it is required that the signal divide as equal or unequal using power divider. Recently, the design of microwave circuits based on new methods such as slow wave applications of electromagnetically induced transparency in microstrip resonator 1 and the automated framework for optimization of miniaturized microwave components 2 have been considered by designers. In most telecommunication systems, power dividers (PD) with equal and unequal power splitting ratios are as an essential element in the feeding network for the antenna array. Comparisons of the measured and simulated results are presented to verify the theoretical predictions. Two proposed TWPDs are fabricated and measured. The center frequency of second designed TWPD is 2.52 GHz, and power-dividing ratio can be controlled up to 1:134 by variation of two DC voltages from 1.7 to 4 V. Since the structure of TWPDs are symmetric, the inverse voltages results in the inverted divided power between the output ports. The center frequency of first designed TWPD is 2.5 GHz, and the power-dividing ratio can be controlled up to 1:45 by variation of two DC voltages from 0 to 8 V. The tunable Wilkinson power dividers (TWPDs) are designed based on IL control components to create a wide range of power-dividing ratios, using only two DC voltages. Then, using the surface current density, it is determined by which part of BPF structure the insertion loss (IL) can be controlled at center frequency. Initially, a narrow-band BPF is designed based on the equivalent circuit model and LC equivalent circuit. This paper presents two narrow-band power dividers with a wide range power-dividing ratio based on the two new controlling insertion loss methods, which are low-impedance line and coupling capacitor. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |