Nazih Khaddaj Mallat

V-band Six-Port Down-conversion Techniques

This paper presents comparative down-conversion results using two different topologies. The conventional approach using anti-parallel diodes acting as LO-driven switches is compared with the six-port one. The proposed down-converter which provides an intermediate frequency of 900 MHz uses a six-port circuit and two pairs of parallel Schottky diodes acting as power detectors connected to two differentials amplifiers. Simulation results of down-converter passive circuits in terms of I/Q IF power and phase are presented and discussed. In addition, comparative analyses are performed in terms of local oscillator and RF power required for the frequency conversion and phase stability. These results show the advantages of the proposed frequency conversion six-port technique.

Millimeter-wave ultra-wideband six-port receiver using cross-polarized antennas

This paper presents a new low-cost millimeter-wave ultra-wideband (UWB) transceiver architecture operating over V-band from 60 to 64 GHz. Since the local oscillator (LO) power required in the operation of six-port receiver is generally low (compared to conventional one using diode mixers), the carrier recovery or LO synchronization is avoided by using second transmission path and cross-polarized antennas. The six-port model used in system simulation is based on -parameters measurements of a rectangular waveguide hybrid coupler. The receiver architecture is validated by comparisons between transmitter and receiver bit sequences and bit error rate results of 500 Mb/s pseudorandom QPSK signal.

V-Band Quadrature Phase Shift Keying Demodulator Using Wr-12 Six-Port

A direct 61GHz demodulator, based on a rectangular waveguide (WR-12) six-port, is presented in this letter. The six-port device, composed of four 90 - hybrid couplers fabricated in a metal block of brass, is implemented in ADS software. Good agreement between QPSK demodulation results using an ideal six-port model and a second one, based on the S-parameter measurements of a 61GHz hybrid coupler, is achieved.

Development of Substrate-Integrated Waveguide Filters for Low-Cost High-Density RF and Microwave Circuit Integration: Direct-Coupled Cavity Bandpass Filters With Chebyshev Response

Direct-coupled cavity bandpass filters with Chebyshev response are studied and realized, using the technique of planar substrate-integrated waveguide (SIW) for the purpose of high-density integration and cost reduction. Using a general mode-matching technique, the scattering matrix of waveguide bifurcation-type discontinuity and asymmetric iris are established and analyzed. Such discontinuities are used as coupling components and building blocks in the design of filters that are realized on RT/duroid 6002 with the ordinary printed circuit board process in our work. Measurement for one of the three four-pole filters gives 3.4 dB insertion loss and 17 dB return loss over the whole passband at near 24 GHz (K-band) with 440-MHz bandwidth (1.8%). The design method can be widely adopted for the development of microwave-integrated circuits, and the mass-fabrication of such SIW filters can be made easy while maintaining a very low cost.

On the design of millimetre-wave antennas for 5G

This paper addresses the millimeter-wave antenna design aspect of the future 5G wireless systems. The paper reviews the objectives and requirements of millimeter-wave antennas for 5G. Recent advances in mm-wave antenna are reported and design guidelines are discussed. In particular, four different designs are identified from the recent literature based on their attractive characteristics that support 5G requirements and applications. The first design employs a dual-band slotted patch antenna operating at 28 GHz and 38 GHz. The antenna has circular polarization and is excited by a single-feed microstrip line. The present design is desirable for high-gain antenna array implementation in the mm-wave band, in order to compensate for the mm-wave propagation loss. The second design that is presented employs a compact planar inverted-F antenna (PIFA) with single layer dielectric load of a superstrate to enhance the gain and achieve a wide impedance bandwidth resulting in high efficiency. The third design that operates in the mm-wave band is a T-Shaped patch antenna. The proposed antenna a wideband range from (26.5 GHz-40 GHz) of the Ka band. The PFT substrate was used as it offers some advantages; low cost, high flexibility, harmless to human body and resistive towards environmental effects. The last mm-wave antenna design presented employs two MEMO arrays each composed of 2×2 antenna elements. The two MIMO array configurations are spatially orthogonal to each other which results in polarization diversity.

Cognitive Chaotic UWB-MIMO Detect-Avoid Radar for Autonomous UAV Navigation

A cognitive detect and avoid radar system based on chaotic UWB-MIMO waveform design to enable autonomous UAV navigation is presented. A Dirichlet-process-mixture-model (DPMM)-based Bayesian clustering approach to discriminate extended targets and a change-point (CP) detection algorithm are applied for the autonomous tracking and identification of potential collision threats. A DPMM-based clustering mechanism does not rely upon any a priori target scene assumptions and facilitates online multivariate data clustering/classification for an arbitrary number of targets. Furthermore, this radar system utilizes a cognitive mechanism to select efficient chaotic waveforms to facilitate enhanced target detection and discrimination. We formulate the CP mechanism for the online tracking of target trajectories, which present a collision threat to the UAV navigation; thus, we supplement the conventional Kalman-filter-based tracking. Simulation results demonstrate a significant performance improvement for the DPMM-CP-assisted detection as compared with direct generalized likelihood-ratio-based detection. Specifically, we observe a 4-dB performance gain in target detection over conventional fixed UWB waveforms and superior collision avoidance capability offered by the joint DPMM-CP mechanism.

Carrier recovery loop for millimeter-wave heterodyne receiver

A carrier recovery loop process, for a millimeter-wave heterodyne receiver, is proposed in this paper. The millimeter-wave frequency conversion is performed using a six-port module, avoiding the conventional millimeter-wave active costly mixers. The second frequency conversion is performed using conventional circuits. The carrier recovery is done at the intermediary frequency (IF) part and not at the millimeter-wave one. In this paper, the carrier recovery is demonstrated by showing the spectrum and corresponding waveform of the recovered signal, extracted through the loop from the IF received signal and used for the second frequency conversion. The bits received are transmitted by an arbitrarily incoming QPSK modulation.

In-phase reflection and band-gap characteristics of EBG structure for millimeter-wave applications

Design and analysis of millimeter-wave (MMW) mushroom-like, circular-patch electromagnetic band-gap (EBG) structure is presented. The in-phase reflection and band-gap characteristics of the proposed EBG structure are investigated. Results show that the proposed EBG structure has stable reflection properties when normally and obliquely illuminated by a plane wave with different polarizations around the 60 GHz band. In addition, the proposed EBG structure is found to have a band-gap around the same frequency bandwidth. With these properties, proposed EBG structure is suitable to be used as reflectors in antenna applications in orderto increase the gain and improve the radiation characteristics.

SIR-based miniaturized EBG structure for millimeter-wave isolation improvement applications

A new uni-planar compact electromagnetic bandgap (EBG) structure is presented. The proposed EBG unit-cell is designed based on the stepped-impedance resonator (SIR) technique. Results show that the proposed EBG structure provides a wide frequency bandgap around the 60 GHz band. Moreover, results show that the proposed EBG unit-cell has further miniaturization factors of 0.79 and 0.66 compared to conventional uni-planar EBG and uniplanar compact (UC-EBG) structures, respectively.

60 GHz Ultra Wideband Multiport Transceivers for Next Generation Wireless Personal Area Networks

Ultra wideband (UWB) communications is one of the most promising recent developments in wireless world for high-speed applications as shown in figure 1. In addition, the use of millimeter-waves has allowed in recent years the development of wireless communications: unlicensed short-range (57 – 64 GHz), outdoor semi-unlicensed point to point links (71 76 GHz, 81 86 GHz, and 92 95 GHz), automotive radar (76 77 GHz), and imaging sensor (84 – 89 GHz and 94 GHz) systems.