This paper presents a hybrid design of 1 × 2 and 1 × 4 arrays operating in 0.277–0.292 THz on 65 nm Complementary metal–oxide–semiconductor (CMOS) technology. Each of the chips has an X-band input with 3 ×3 multiplier stages and connected at the output to an on-chip ring antenna. A wideband microstrip Wilkinson four-way and two-way power dividers have been developed on a multilayer printed circuit board to feed the array elements with proper radio frequency and direct current inputs. Demonstrating improvements in effective isotropically radiated power and in total radiated power compared to a single CMOS element, the hybrid integration approach proves effective in implementing coherent THz transmitter arrays. Theoretical and practical factors that reduce the radiated power compared with ideal arrays are also discussed.

Aperture-coupled ESPAR antenna with a unique feed structure for switched beam application has been presented. The feed structure provides control over surface current of the driven element with the help of which main lobe can be steered in desired direction. This control has been achieved through the use of PIN-diodes. Finite element method has been utilized for design and simulated and measured results have been presented for validation. The antenna has the ability to steer the main beam in six directions. All radiation patterns are symmetric. The planar aperture-coupled nature of proposed antenna is ideal for integration and commercialization.

In this paper, significance of studying the nonlinear performance of amplifying reflectarray antenna is clarified by showing nonlinear behavior of the unit cell. Furthermore, the procedure for nonlinear analysis of amplifying reflectarray antenna is described and nonlinear analysis is verified by ADS software simulation. Moreover, a typical amplifying reflectarray antenna is designed considering the nonlinear behavior. Nonlinear analysis of the active aperture-coupled patch unit cell is performed using harmonic balance method considering nonlinear model of the amplifier. Then, the effect of nonlinear element in radiation pattern of the antenna is studied. Passive unit cell is simulated using full-wave analysis method considering infinite array approach, and scattering parameters of the unit cell is obtained. Next, these scattering parameters are transformed to admittance parameters and used in obtaining nonlinear response and harmonic distortion of the unit cell containing amplifier. Obtained results show up to 3.4 dB error in predicting pattern of the antenna with linear modeling of the active element.

The purpose of this paper is twofold. It first describes how Microwaves were progressively organized by Professional Engineering Institutions in Europe in the years 1960–2000, essentially through individual efforts over many years. The first formal Microwave event organized in Europe was the European Microwave Conference in London, 1969, opening a series that continues as the European Microwave Week. It then shows that, over the same period of time, the Institute of Radio Engineers (IRE), USA, which merged in 1963 with the American Institute of Electrical Engineers, USA, to form the Institute of Electrical and Electronic Engineers (IEEE), also became stronger in Europe. European IRE members developed the structure of the IRE in Western Europe, with a first Regional meeting in Geneva, 1962. The paper illustrates the development of both Microwave Engineering and IRE-IEEE in Europe in the period of time considered, thanks to the commitment of European individuals, some of whom have been active on both counts.

A novel asymmetric “+” shaped fractal slotted circularly polarized microstrip antenna with a Yagi–Uda structure is proposed. Four asymmetric plus shape slots are embedded symmetrically in the center of all four quadrants of a square patch. To suppress undesirable higher modes, dumbbell-shaped defected ground structure (DGS) is introduced at the ground layer of the antenna. We introduce a method to compensate the reduction in gain occurring due to the presence of DGS, without changing in the overall size of the antenna. A 3 dB axial ratio bandwidth of 4 MHz at center frequency of 862 MHz, 10 dB impedance bandwidth of 13.20 MHz and a gain of 4.25 dB is achieved with the proposed antenna. A laboratory prototype of the proposed antenna is made to cross-verify the simulation results. Very good agreements between the two are obtained. The proposed antenna may prove useful for International Mobile Telecommunication application for designing high-gain arrays.

A new split frequency envelope modulator for envelope tracking radio-frequency power amplifiers is proposed based on a lead-lag network. By mathematically deriving the transfer functions of the lead-lag modulator and the conventional split frequency type, the lead-lag is shown to have a significantly flatter phase response. The frequency response of the two modulators is verified by simulation, where the phase transient of the lead-lag is significantly less than the 360° of the conventional type. They are further simulated with a 3 MHz bandwidth 3GPP long-term evolution (LTE) signal and the lead-lag shown to reduce the modulator's normalized root-mean-square error (NRMSE) from −27.3 to −39.2 dB. A practical demonstrator was developed around an existing high-efficiency modulator architecture. To maintain system efficiency synthetic impedance was incorporated in the low-frequency switched mode power supply (SMPS) path. This was achieved with voltage and current feedback around the SMPS. The dynamic wideband signal response was investigated by applying a 3 MHz LTE envelope signal to the modulator and comparing the input and output signals. The measured NRMSE was improved from −27.5 to −30.0 dB by adopting the lead-lag structure and the dynamic frequency response verifies correct operation.

This paper proposes a technique to design wide band switched-line (SL) true-time-delay (TTD) networks, commonly used for phased array antenna (PAA) applications. This study investigates the constant-delay behavior of switched-line phase shifters based on single-pole double-throw (SPDT) switches. Circuit sizing starts by considering the effective S-parameters of the switches, to use their non-idealities as an integral part of the phase shift linearly dependent to the frequency and by considering, from the beginning, the possible spatial positioning of elements that allows the circuit feasibility as a design target. The aim of this study is to provide a technique suitable for the design of well-matched TTD networks with a flat delay in wide bandwidth. In this paper, we propose new design formulas for which we show a single-frequency implementation. A computational strategy is used to obtain numerical solutions of the derived equations with this study. Finally, a monolithic X-band TTD circuit example is shown.

A compact navigation receiver comprising a decoupled and matched four-element L1-band antenna array with an inter-element separation of a quarter of the free-space wavelength is presented in this paper. We investigate the impact of the decoupling and matching network on the robustness of the navigation receiver. It is observed that in order to achieve high robustness with a compact antenna array, it is necessary to employ a decoupling and matching network, particularly in case of three spatially separated interferers. Furthermore, we study the influence of the polarization impurity of the compact planar antenna array on the equivalent carrier-to-interference-plus-noise ratio (CINR) of the receiver when impinged with different numbers of diametrically polarized interference signals. It is shown that the higher-order modes possess strong polarization impurity, which may halve the available degrees-of-freedom for nulling in the presence of linear-polarized interferers, using a conventional null-steering algorithm. We verify the robustness of the designed compact receiver by means of a complete global-navigation-satellite-system demonstrator. It is shown that the maximum jammer power that is allowed us to maintain the CINR above 38 dBHz with three interferers can be improved by more than 10 dB if a decoupling and matching network is employed.

This paper presents results of direction of arrival (DOA) estimation using multiple signal classification (MUSIC), Root-MUSIC, and estimation of signal parameters via rotational invariance technique algorithms. As is well known, these algorithms are mainly based on the specific properties of the signal covariance matrix as well as the decomposition of the observation space into two subspaces, one for the signal and the other for the noise. Here, we are particularly interested in the quality of sources localization considering only the case of uncorrelated radio frequency signals impinging on an antenna array. A measurement system consisting of a linear array antenna and a five-port network applicable to a demodulator such as a receiver is used for the DOA estimation process. Co-simulations performed with the Advanced Device System and Matlab yielded interesting results not only on their performance but also on their limitation.

A simple and volume efficient circular antenna-array design with a low profile programmable beam rotation mechanism was presented. The proper selections of the rotation vector and the excitation coefficients of rectangular array-elements were made for rotation of the beam. The proposed rotation mechanism was capable to rotate the radiation pattern at any desired speed and to transmit in any desired direction, and the design included the ease of construction. Although simulating the radiation pattern using FEKO EM simulator, two basic functions, the power splitter and the introduction of phase difference, were included in feed network of microstrip circuit to divide the power and then individually feeding the each patch after introducing the desired phase difference.

This paper presents a radio frequency (RF) continuous-time band-pass delta sigma modulator (CT BP DSM) receiver realized in a 180 nm SiGe BiCMOS technology. It also provides an introduction to active antenna systems (AAS) for cellular infrastructure base stations, which is the target application for this RF integrated circuit (IC). The internal quantizer and feedback digital to analog converter (DAC) resolution of the CT BP DSM is 2 bit. Without applying DAC linearization techniques such as trimming or dynamic element matching being utilized, measured performance parameters include an SNR and SNDR in 35 MHz bandwidth of 56.7 and 53.7 dB, respectively. IIP3 and noise figure are −6.6 dBm and 10 dB, respectively. No image reception is noticeable within a measurement dynamic range of 83 dB. When driven by single-carrier and three-carrier W-CDMA signals, adjacent channel leakage ratio (ACLR) is −62.6 and −52.1 dB, respectively, making the design also suitable as a modulator for a class-S power amplifier.

This paper reports the test results of a small-scale prototype that implements a digitally beam-formed phased antenna array in the E-band. A four-channel dual-conversion receive RF module for 71–76 GHz frequency band has been developed and integrated with a linear end-fire antenna array. Wideband frequency-domain angle-of-arrival estimation and beam-forming algorithms were developed and implemented using Orthogonal Frequency Division Multiplexing (OFDM) with Quadrature Phase-Shift Keying (QPSK) at 1 Gbps. Measured performance is very close to the simulated results and experimental data for an analogue-beam-formed array. This work is a stepping stone toward practical realization of larger hybrid arrays in the E-band.