Abstract: The present disclosure provides a novel brassinosteroid (BR) analogue, a novel crystal form, and a preparation method and use thereof. The BR analogue has a chemical formula of C27H46O7, a chemical name of (20R,22R)-2?,3?,14?-14,20,22,25-hexahydroxy-5?,8?,9?-cholestan-6-one, and a structural formula of: In the present disclosure, a novel crystal form with a high bioactivity is obtained by improving a recrystallization process of a naturally extracted BR analogue. This novel crystal form can be applied in the field of agriculture to promote the growth of plants.

Abstract: A transformer based power amplifier introducing leakage inductance to extend a working bandwidth thereof and corresponding design methodology are provided. An ultra-wideband transformer comprises a primary coil, a secondary coil mutual coupling with the primary coil, a primary tuning capacitor coupled with the primary coil in parallel and a secondary tuning capacitor coupled with the secondary coil in parallel. By means of setting a self-inductance of the primary coil, a self-inductance of the secondary coil, a mutual coupling factor between the primary coil and the secondary coil, a capacitance value of the primary tuning capacitor, and a capacitance value of the secondary tuning capacitor, a 3 dB bandwidth of the transformer covers a first mutual resonated frequency and a second mutual resonated frequency formed by the transformer.

Abstract: A predistortion linearizer for a microwave power amplifier comprises a signal separator for receiving a signal and dividing the signal into first and second signals, a first path for carrying the first signal and a second path for carrying the second signal, and a signal combiner for combining the signals from the first and second paths. The second path between the separator and combiner includes a non-linear device for receiving the second signal and generating distortion therefrom, and a vector modulator for controlling at least one of the amplitude and phase of the second signal.

Abstract: A predistortion linearizer for a microwave power amplifier comprises a signal separator for receiving a signal and dividing the signal into first and second signals, a first path for carrying the first signal and a second path for carrying the second signal, and a signal combiner for combining the signals from the first and second paths. The second path between the separator and combiner includes a non-linear device for receiving the second signal and generating distortion therefrom, and a vector modulator for controlling at least one of the amplitude and phase of the second signal.