Quad-Band NGD Investigation on Crossed Resonator Interconnect Structure

This brief explains why the coupling between crossed interconnect structure and straight I-lines of printed circuit board (PCB) presents bandpass (BP) negative group delay (NGD) behavior. The NGD effect is investigated with crossed resonator innovative microstrip equivalent topology. As proof of concept (POC), the influences of crossed resonator circuit physical variables on the BP-NGD behavior are illustrated by parametric study. The cross-coupled microstrip circuit POC BP-NGD responses is validated with quad-band NGD behavior. A very good agreement between calculations, simulations and experimentations state results of NGD center frequency-NGD value, (1.541-GHz, −1.84-ns), (2.397-GHz, −1.6-ns), (3.379-GHz, −1.38-ns), and (4.164-GHz, −0.91-ns) representing the 1st, 2nd, 3rd and 4th NGD band, respectively. The studied design has notable advantages in term of NGD application integration in the multi-band transceiver system simplicity and size reduction

EMI Characterization from GaN Power Amplifier Nonlinearity Test for 16-QAM 5G Communication

Today, the anywhere, anyhow and anytime application scenarios of 5G system force designer to challenge on electromagnetic interference (EMI) requirements. Despite the technological progress, relevant test techniques are necessary to minimize the future communication system EMI risk. In this paper, the EMI characterization from nonlinearity (NLT) of 5G system Gallium Nitride (GaN) power amplifier (PA) is studied. Firstly, the PA NLT is evaluated by 1-dB/3-dB/6-dB compression point and 3rd-order intermodulation distortion (IMD3). Then, a measurement platform is built based on vector signal generator and EMI receiver including digital modulation system. According to the adjacent channel leakage ratio (ACLR), error vector magnitude (EVM) and signal-to-noise ratio (SNR), the EMI characteristics of 3.5-GHz carrier signals modulated by 16-Quadrature Amplitude Modulation (16-QAM) distorted by the GaN PA NLT are discussed. Due to the GaN PA 3rd order intermodulation (IM3) product, the SNR degrades from 34.8 dB to 14.6 dB when the input signal power increases from –10 dBm to 6 dBm. The EMI effect is confirmed by significant signal distortion observed with 16-QAM constellation diagram. Research work is currently ongoing for extending the EMI test technique for 6G communication system

Nonlinear Microwave Device LabVIEW Automatic Test Bench: Double-Frequency IMD3 Characterization

The active component nonlinear (NL) effect causes undesirable RF and microwave system electromagnetic interference (EMI) problems which penalizes the communication system performance by signal distortion. Therefore, a relevant NL component measurement method is needed to predict the transceiver system EMI effect. However, the NL measurement characterization of RF and microwave active devices remains a fastidious and time cost task. An innovative NL test bench automatized by LabVIEW®control interface is featured in this research work. The design technique of the NL test methodology is described. The developed automatic test bench is tested with a microwave power amplifier (PA) operating at 2.4 GHz based on double-frequency (DF) method. The experimental test setup including the LabVIEW®test control parametrization and data acquisition is described. The test bench effectiveness was assessed by the third-order intermodulation (IMD3) PA measurement with DF method. The theoretically calculated and measured IMD3 amplitudes based on DF input signal are in very good correlation. Thanks to its advantages in terms of simplicity, flexibility, and time cost, the innovative NL automatic test bench is very useful for transceiver system EMI analyses

Electric near-field scanning for electronic PCB electromagnetic radiation measurement

This paper introduces a design and test of an electric (E) near-field scanning (NFS) system by using innovative 4- layer miniature probe for electromagnetic compatibility (EMC) application. The probe works in the challenging frequency band up to 12 GHz with spatial resolution lower than 2 mm. The NFS is designed to operate by automation based on PC driven by LabVIEW® interface controlling a vector network analyzer (VNA). The PC communicates with the VNA through the local area network to read and save the measured data emitted by the device under test (DUT). The LabVIEW® interface is designed to control the E-NF positioning motion core by means of STM32® microcontroller. A stepper motor is used to move the E-NF probe along the scanning surface plan. Finally, the NFS is validated by visualizing the E-NF intensity maps generated in real time after calibration with a reference device under test represented by microstrip line and a microwave circuit

Nonlinear Modelling of K-Band GaN Power Amplifier

An innovative nonlinear (NL) modeling of K-band power amplifier (KPA) designed and fabricated in Gallium Nitride (GaN) technology operating at frequency f0 = 24 GHz is investigated in this paper. Two KPA prototypes are characterized by single-and double-frequency tests (SFT and DFT). Then, fitting memory NL model from SFT established for input-output power (Pin-Pout) characteristic f0 enables the confirmation of KPA performance. Accordingly, the KPA presents 27.8 dB gain when Pin increases from −5 dBm to 20 dBm, 40.8 dBm saturation output power, and 38.6% saturation power added efficiency (PAE). Moreover, the DFT with f1 = 23.995 GHz and f2 = 24.005 GHz enables the assess to the third-order intermodulation distortion (IMD3) which is assessed from 10.4 dBc to 35 dBc. The KPA critical IMD3 is identified with the Pout variation range from 16.35 dBm to 36.35 dBm. The developed NL model is useful in the future for the electromagnetic interference prediction of multi-carried front-end transceiver communication system due to NL distortion signal

A Novel W-Band Dual-Polarized Cassegrain Antenna for Cloud Radar

Abstract-A W-band dual-polarized Cassegrain antenna for cloud radar is proposed. The aperture diameter of the main reflector of the antenna is 50 cm. By using a modified Magic-T structure in the feed horn, the antenna is dual-polarized with high port isolation. The measured results show that the port isolation is 44.7 dB. The gains are 47.3 dB and 49.5 dB for the two ports at 94 GHz, respectively, and the efficiency of the antenna is better than 87%

NGD Bandpass Type Characterization of Circular Curved Coupled-Line

The present study examines the negative group delay (NGD) behavior of a circular curved (CC) coupled-line (CL) microstrip circuit with a bandpass (BP) characteristic. The novel CC CL-based circuit is derived from the curved li-topology which demonstrates BP-NGD functionality. The basic theoretical approach enabling the BP-NGD analysis is introduced. The BP-NGD function main properties related to NGD center frequency, NGD value, and NGD bandwidth are defined. Despite the progressive NGD research work, it was wondered how the RF printed circuit board trace geometrical parameters such as curvature radius and angle change the microwave communication parameters. To verify the BP-NGD concept feasibility, different microstrip prototypes are designed, simulated, fabricated, and tested as the proof of concept (POC). Thus, a developed empirical study of CC microstrip structures corroborating well-correlated simulations and experimental results is examined. Moreover, deep sensitivity analyses for geometrical design parameters were performed using commercial tool full-wave simulations. The obtained results provide insights into the effects of CC-structure inter-space and curvature angles on the inherent BP-NGD parameters. The proposed NGD circuit is potentially useful in the future in RF and microwave engineering for signal delay correction. Additionally, it helps in understanding the characteristics of microstrip PCB traces that are important for optimizing signal integrity (SI), power integrity (PI), and electromagnetic compatibility (EMC)

Experimental Investigation of Characteristics and Development of Nonlinearity Models for FR1-Range Radio-Frequency Amplifiers

Experimental studies of nonlinear properties of low-power radio-frequency amplifiers similar to those used in 4G/5G mobile communication equipment of the FR1 frequency range are carried out. The measurements of the characteristics of the amplifiers are performed by using the double-frequency testing technique at frequencies of the n7 band (2500–2570 / 2620–2690 MHz), which is allocated in Belarus for 4G mobile communication systems, and the n78 band (3300–3800 MHz), which is planned to be used in Belarus for 5G mobile communications. Based on the results of the measurements of double-frequency characteristics of the amplifiers, their single-tone amplitude characteristics, as well as two-tone characteristics and values of the dynamic range of 3-, 5-, 7-, and 9th order intermodulation in the first harmonic zone, high-order polynomial models of transfer characteristics of the investigated amplifiers are synthesized. The synthesized models are suitable for use in a wide dynamic range of input signals in case of simultaneous modeling of nonlinear effects of all kinds that pose a danger to radio reception in a complex electromagnetic environment created in the frequency bands of mobile (cellular) communications: both “subtle” effects (intermodulation) and “rough” effects (desensitization, cross-modulation). When using the technology of discrete nonlinear analysis of the behavior of radio equipment in a complex electromagnetic environment, the obtained models provide high efficiency of simulation and quantitative analysis of nonlinear processes and radio interference occurring in 4G/5G/6G radio equipment and networks in a complex electromagnetic environment

Nonlinear Testing-Based EMI Characterization of Wireless Communication Transmitter with Microwave Power Amplifier

An effective empirical method of EMI analysis for transceiver (Tx-Rx) system implemented with nonlinear (NL) microwave power amplifier (MPA) dedicated to wireless communication is developed. The nonlinearity is experimentally quantified by the MPA gain, P1dB, and third order intermodulation component via spectral response around 2.4 GHz 802.11b IEEE frequency band. The proof-of-concept represents the Tx-Rx system environment for wireless communication. The considered test signal emulates synchronization and physical broadcast different channels of downlink communication signals under QPSK modulation. The error vector magnitude (EVM) and signal-to-noise-ratio (SNR) due to the microwave Tx-Rx transmission undesirable EMI effect are assessed. Without MPA, the EVM and SNR of various channels fluctuate within a small range. Because of MPA nonlinearity, EMI becomes awfully significant due to the intermodulation generating SNR 20-dB decrease