Frequency-independent Phase Shifter Research Articles

Vivaldi Antenna Arrays Feed by Frequency-Independent Phase Shifter for High Directivity and Gain Used in Microwave Sensing and Communication Applications.

This paper describes a novel feed system for compact, wideband, high gain six-slot Vivaldi antenna arrays on a single substrate layer using a unique combination of power splitters based on binary T-junction power splitter topology, frequency-independent phase shifter, and a T-branch. The proposed antenna system consists of six Vivaldi antennas, three on the left, and three on the right arm. Each arm connects with T-junction power divider splitter topology, given that the right arm is linked through a frequency-independent phase shifter. Phase shifters ensure that the beam is symmetrical without splitting in a radiating plane so that highly directive radiation patterns occur. The optimal return losses (S-parameters) are well enriched by reforming Vivaldi’s feeding arms and optimizing Vivaldi slots and feeds. A novel feature of our design is that the antenna exhibits the arrangements of a T-junction power splitter with an out-of-phase feeding mechanism in one of the arms, followed by a T-branching feeding to even arrays of proper Vivaldi antenna arrangement contributing high realized gain and front-to-back ratio up to 14.12 dBi and 23.23 dB respectively applicable for not only ultra-wideband (UWB) application, also for sensing and position detecting. The high directivity over the entire UWB frequency band in both higher and lower frequency ranges ensures that the antenna can be used in microwave through-wall imaging along with resolution imaging for ground penetration radar (GPR) applications. The fabricated antenna parameters are in close agreement with the simulated and measured results and are deployed for the detection of targets inside the voids of the concrete brick.

Highly Efficient Front End Direct Conversion Receiver for 28-GHz Wireless Access Point

The manuscript presents the design and characterization of a wideband front-end receiver, based on hollow waveguide technology, for the wireless access point (WAP) applications. The Ka-band receiver is comprised of a low-loss beam-switching antenna network (BSAN) with two-dimensional (2D) scanning property. For demodulation, the receiver uses an efficient six-port network (SPN) that is composed of four 90° hybrid couplers and a 90° phase shifter. To suppress the phase imbalance on the entire band of interest, 27 GHz to 33 GHz, a frequency-independent phase shifter with a minimum phase error is suggested. The SPN receiver is integrated with antenna-in-package in waveguide technology to decrease the insertion losses and noise levels at the first stages. To determine the SPN phase errors, a theoretical and experimental analysis of real-time wireless data transmission utilizing phase-shift keying (PSK) and quadrature amplitude modulated (QAM) signal is conducted. Besides, channel capacity along with beamformer influence on channel performance improvement are determined.

Multi-pole multi-zero frequency-independent phase-shifter

A multi-pole, multi-zero design allowed realizing a "true" phase-shifter (not time-delayer) of flat frequency-response over more than three decades (30 Hz-100 kHz), which can be extended to higher frequencies or broader bands thanks to a modular design. Frequency-dependent optimization of a single resistance made also the gain flat to within few percents. The frequency-independent phase-shifter presented can find application in any experiment in which an action needs to be taken (e.g., a measurement needs to be performed) at a fixed phase-delay relative to an event, regardless of how rapidly the system rotates or oscillates.

Low-cost sensorless control of brushless DC motors using a frequency-independent phase shifter

This paper describes a sensorless control scheme for brushless DC motors (BLDCMs) using a phase shifter (FlPS) which can shift the zero-crossing point of the input signal with a specified amount of phase. The detection performance of the proposed FIPS is independent of the frequency of the input signal and quite robust with respect to the measurement noise. It is shown that the proposed sensorless control scheme using the FIPS is more effective in the respects of noise-robustness and cost than the previously known schemes. Moreover, a flux-weakening control scheme can be easily incorporated into the proposed sensorless control scheme. The generality and practicality of the proposed sensorless control scheme is demonstrated through performance analysis and experiments under various operating conditions.

Precision frequency-independent variable-phase phase shifter

A frequency-independent phase shifter, that provides a precise phase shift, variable from 0 to 360°, is described. With the use of a microcontroller and feedback arrangement, the phase shift depends only on the ratio of two DC voltages. A stable, drift-free operation with good accuracy is hence obtained over the AF range.

A frequency-independent phase shifter

Describes a circuit which produces, over a restricted frequency range, a frequency independent phase shift and an invariant amplitude. The circuit uses switched capacitor techniques to ensure linearity and to simplify the setting up procedure.

A frequency-independent phase shifter

The circuit described gives the frequency-independent phase shift for a band-limited signal, while keeping its amplitude invariant. The key component is a field-effect transistor which, driven by a frequency discriminator, provides a resistance which is inversely proportional to the frequency. A prototype circuit produces a phase shift flat to within +or-2 degrees over the frequency range from 20 to 40 kHz.