A longitudinal space charge amplifier (LSCA), operating in soft x-ray regime, was recently proposed. Such an amplifier consists of a few amplification cascades (focusing channel and chicane) and a short radiator undulator in the end. The broadband nature of LSCA supports generation of few-cycle pulses as well as wavelength compression. In this paper we consider an application of these propertie...

A novel method for the excitation of ELF waves in the ionosphere is presented. It utilizes the nonlinear mixing of two groundor satellite-produced radio frequency waves with a compressional Alfv6n wave. Parametric amplification thresholds are estimated to be between 10 and 20 MW peak power for 5-MHz pumps producing waves in the ELF range. Potential applications to ELF communications are discussed.

For massive MIMO public channel with any sector size in either microwave or millimeter wave (mmwave) band, this paper studies the beamforming design to minimize the transmit power while guaranteeing the quality of service (QoS) for randomly deployed users. First the ideal beampattern is derived via Parseval Identity, based on which a beamforming design problem is formulated to minimize the gap ...

A brief analysis of methods and features measuring thermal parameters integrated microwave power amplifiers on bipolar transistors (BT) is presented. The hardware software complex implementing the method amplifier according to OST 11 0944-96 original modulation described. In both methods, temperature active region BT crystals determined by a change in certain temperature-sensitive parameter (TS...

With the advent of spectrally efficient wireless communication systems employing modulation schemes with varying amplitude of the communication signal, linearization techniques for nonlinear microwave power amplifiers (PAs) have gained significant interest. In this article, a low complexity, direct-learning multilevel lookup table based adaptive digital predistortion technique has been proposed...

A novel structure that encodes and decodes very high speed unipolar Code Division Multiple Access (CDMA) signals is proposed. This scheme is based on the analogy between the distributed amplifier and the transversal filter. By adjusting the gain of each tap and the delay between taps, the proposed device acts as a high-speed encoder (transmitter) or correlator (receiver). The theoretical analys...

This paper presents a new approach for the global electromagnetic analysis of the three-Terminal active linear and nonlinear microwave circuits using the Finite-Difference Time Domain (FDTD) Method. Here, we have updated the both electric field components on the three terminal active device by correlating the voltage and current with its impedance. This approach is applied to the analysis of a ...

Understanding electromagnetic wave phenomena is very important to be able to design RF cavities such as for atmospheric microwave plasma torch, microwave vacuum oscillator/amplifier, and charged-particle accelerator. This chapter deals with some electromagnetic wave equations to show applications to develop the analytic design formula for the cavity. For the initial and crude design parameter, ...

A high-linearity and high-efficiency MMIC power amplifier is demonstrated adopting a new on-chip adaptive bias circuit, which improves efficiency at the low output power level and linearity at the high output power level automatically. The intelligent two-stage W-CDMA power amplifier using the newly proposed adaptive bias circuit extends the maximum linear output power of 0.6dB and exhibits an ...

We address the peak power scaling of our DPSS MOPA system from 10 MW to >100 MW (anticipated) at multi-kHz for OPCPA pumping. We discuss the challenges in scaling this Nd-based picosecond amplifier system. OCIS codes: (140.0140) Laser and laser optics; (140.3280) Laser amplifiers