Quadrupole gyromagnetic ferrite circular variable polariser loaded with a dielectric ring

Che, Wenquan; Yung, E.K.N.; Sha, Kan; Wen, Jihong

doi:10.1049/ip-map:20010219

Cited by 1 publication

(2 citation statements)

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“…It is necessary to ensure that TE 11 is the dominant mode, and to determine under what conditions the TE 11 mode can propagate in the device. An investigation of single-mode transmission in the ferrite variable polarizer in the circular waveguide [7] has been carried out. Firstly, the cutoff characteristic equation for the modes in the circular waveguide filled with three dielectric layers was derived, and the conditions that guarantee the single-mode transmission in the ferrite variable polarizer were determined.…”

Section: Introductionmentioning

confidence: 99%

“…However, due to the nonlinearity of the inverse-scattering problem, there is a risk that the solution will be trapped in a local minimum. The stochastic methods [7,8], though globally convergent, are extremely computation intensive, especially when the number of unknowns is high. One way to minimize the risk of local minima is to use prior knowledge about the scatterer, so that the nonlinear problem is linearized about a different background [4].…”

Section: Introductionmentioning

confidence: 99%

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On single‐mode transmission of variable ferrite polarizers in circular waveguide

Che

Yung

2004

Micro & Optical Tech Letters

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two-stage 2110 -2170-MHz power amplifier was built for the purpose of linearization. Its final stage used a LDMOS MRF21336 amplifier by Motorola. The overall gain of this lineup is 44 dB and the P1dB is approximately 35 dBm. Figure 5 shows the measured results of the first experiment for a four-carrier W-CDMA test signal (20-MHz signal bandwidth). Figure 5(a) shows the output spectral power with and without the predistorter at an output power of 24 dBm. Before linearization, the output power of the power amplifier was 24 dBm and the ACLR was Ϫ40.0 dBc. After linearization, the output power was the same but the ACLR was Ϫ45.8 dBc, an ACLR improvement of 5.8 dB. Figure 5(b) shows the ACLR improvement over a range of output powers from 18 to 33 dBm.For the second experiment, a three-stage 2100 -2170 MHz power amplifier was built for the purpose of this study. Its final stage used two LDMOS MRF21085 devices by Motorola. The second stage was built on the LDMOS MRF21045 amplifier. The first stage used a gain block to drive the two other stages. The overall gain of this lineup is 51 dB and the output power at 1-dB gain compression is approximately 51 dBm. Figure 6 shows the measured results of the second experiment by the four-carrier W-CDMA test signal (20-MHz signal bandwidth). Figure 6(a) shows the output spectral power with and without the predistorter at an output power of 38 dBm. An ACLR improvement of 4.7 dB was obtained. Figure 6(b) shows the ACLR improvement over a range of output power from 31 to 45 dBm. CONCLUSIONA new analog predistorter using a Cartesian vector modulator structure has been demonstrated. This predistorter can easily accommodate four different types of gain and phase characteristics through independent bias adjustments of the two IM generators. We have analyzed the operation principle of the proposed predistorter. To verify the proposed predistorter, a W-CDMA fourcarrier linearization test was performed at a frequency of 2120 MHz. The results showed that an ACLR improvement over a broad range of output power levels is possible. This predistorter can be easily linked to an appropriate adaptation control circuit that has a few control parameters.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%