A novel shape penta-band microstrip patch antenna is presented in this paper. The proposed antenna shows five operating frequencies and can be used for various wireless applications, i.e. 2.58 GHz for non-direct line of sight, wireless Internet service providers, and compatible with Navini Networks; 3.17 and 3.42 GHz for WiMAX; 4 GHz for C-band application such as weather radar systems; and 5.3 GHz for higher WLAN. Very small frequency ratios of the values 1.2286, 1.078, 1.169, and 1.325 are achieved between two consecutive resonant frequencies. Antenna design techniques for achieving five bands are presented and discussed step by step. The analysis is done by Ansoft HFSS v.15, and results are verified with experimental results of fabricated prototypes.

Metamaterial transmission lines can be realized as a combination of right- and left-handed transmission line (TL) sections exhibiting positive and negative dispersion. This approach gives additional degrees of freedom for improving the performance of microwave devices. Artificial right- and left-handed sections, which are based on lumped-element unit cells consisting of inductance and capacitances (LC-cells), are used. This makes it possible to decrease dimensions of the devices drastically. Furthermore, using variable capacitors in LC-cells allows designing tunable devices. This paper presents the results of design, numerical simulation, and experimental investigation of a tunable rat-race ring and free-of-spurious response dual-band filter manufactured as integrated ceramic multilayer circuits based on low-temperature co-fired ceramics. Commercial semiconductor varactors have been used as tunable components.

This paper presents the design and implementation of power amplifiers using high-power gallium nitride (GaN) high electronic mobility transistor (HEMT) powerbars and monolithic microwave integrated circuits (MMICs). The first amplifier is a class AB implementation for worldwide interoperability for microwave access (WiMAX) applications with emphasis on a low temperature cofired ceramics (LTCC) packaging solution. The second amplifier is a class S power amplifier using a high power GaN HEMT MMIC. For a 450 MHz continuous wave (CW) signal, the measured output power is 5.8 W and drain efficiency is 18.5%. Based on time domain simulations, loss mechanisms are identified and optimization steps are discussed.

In this paper, a metasurface-based aperture-coupled circularly polarized (CP) antenna with wideband and high radiation gain is proposed and analyzed. The proposed antenna is comprised of coplanar waveguide coupling with 4 × 4 corner truncated square patches, which show compact size and low profile. The mechanism of the CP antenna is analyzed theoretically based on the mode analysis and equivalent circuit analysis. The parameters of feeding structure and truncated corner are studied and optimized to achieve wide impedance bandwidth (BW) and axial ratio (AR) BW. Finally, an overall size of 38.8 mm × 38.8 mm × 3.5 mm (0.71λ0 × 0.71λ0 × 0.064λ0 at 5.5 GHz) CP antenna is proposed and fabricated. The simulated results demonstrate that over 41.7% impedance BW (S11 < −10 dB) of 4.55–6.95 GHz and 3 dB AR BW of 5.05–6.15 GHz (fractional BW is about 19.6%) are achieved. In addition, the antenna yielded a broadside CP radiation with a high gain average about 7.5 dBic. Experimental results are in good agreement with the simulated ones.

In this paper, the design of a graded honeycomb radar absorbing structure (RAS) is presented to realize both a wide bandwidth and absorption over a wide range of angles. For both transverse-electric and transverse-magnetic polarization, a fractional bandwidth of more than 118.6% is achieved for at least a 10 dB reflectivity reduction when the incident angle is <45°, an 8 dB reduction when the incident angle is <55° and a 5 dB reduction when the incident angle is <70°. Meanwhile the 10 dB reduction upper angle limit is approximately 30° for the uniform coating honeycomb RAS in the literature, which loses its absorbing ability when the incident angle is larger than 55°. Furthermore, the total thickness of our design is 10.7 mm, which is only approximately 1.29 times that of the theoretical limitation. The good agreement between the calculated, simulated, and measured results demonstrates the validity of this optimization.

Millimeter-wave band-pass filters using spherical dielectric resonators are presented. The dielectric spheres are sandwiched between metal plates and are excited by a simple microstrip line structure on a thin-film circuit board. As such, these filters could also be implemented in the back-end-of-line layers of an integrated circuit. A single resonator, based on a diameter 0.6 mm alumina ceramic sphere, is shown to resonate with high unloaded Q-factor of 750 at 170 GHz. A three-sphere band-pass filter is measured showing <5 dB insertion loss and 0.4% bandwidth at 170 GHz. A concept for mechanically tuning of a two-sphere band-pass filter is demonstrated for a filter operating around 105 GHz. The measured filter shows approximately 5 dB insertion loss and <0.5% bandwidth and its passband can be varied over 3 GHz of frequency, or 3%. Technological challenges are discussed.

In this article, an ultra-wideband printed flexible monopole antenna is proposed for indoor wireless communications. A flexible Rogers RO3003 is used as a substrate, and its performance is estimated for a flat state and when subject to bending along the y-axis. A 2.45 and 5.8 GHz dual-band textile artificial magnetic conductor (AMC) surface consisting of a 4 × 4 unit-cell array was integrated into antenna design with optimum separation distance to extend its potential applications to wearable on-body communications. The specific absorption rate (SAR) levels were numerically investigated using the Hugo human voxel model at both frequencies to evaluate the on-body safety level. Detailed analysis is presented for antenna designs of flat and bent states in free space and on the human body. The proposed UWB flexible antenna has the size of 41 × 38 × 0.25 mm (0.33λ0 × 0.31λ0 × 0.002λ0 at 2.45 GHz). It was added at a distance of 3 mm above a textile AMC surface of 99 × 99 mm. The integrated model is fabricated and experimentally characterized. Measured data and numerical results show that the impedance matching and radiation characteristics are slightly affected by introducing the bending and human body loading. With these remarkable features, the integrated model can be utilized for wireless indoor and wearable applications.

Airbus Italia recently developed enhanced passive components as key elements for its telecommunication Ku-band antenna product lines, tailored to reconfigurable payloads. This paper describes the design and qualification of a dual linear polarization Ku-band-radiating chain, developed for the DRA receive (Rx) active antennas embarked on the Eutelsat Quantum satellite. The feed chain covers the entire Ku-band frequency range allocated for fixed satellite services providing receive functionality and embedding sharp rejection features over the adjacent transmit band. The proposed design provides high radiation efficiency (>90%) and polarization purity (XPD > 33 dB), together with low RF losses and flat group-delay variation over a 13% fractional bandwidth, keeping a compact size and reduced axial length. The unit has been optimized for high reproducibility in high volume productions, typical of large DRA applications, for which stringent mass and dimensional constraints, as well as excellent amplitude and phase tracking among similar units, are key features. Details of the feed chain design and an overview of RF and environmental qualification test results are presented.

This manuscript deals with the development of a novel configuration of a wide-band single-layer frequency selective surface (FSS) for wide-band rejection applications. The established unit cell is composed of a simple circular ring on the top side of the substrate and a combined conductive element on the backside. Such an inclusion of conductive elements and accurate tuning of their dimensions ends in the rejection of a wide frequency band extended from 6.3 to 16.3 GHz. Moreover, the proposed structure exhibits a stable response against different angles of incidence for both TE and TM polarizations. Detailed simulation and measurement studies are carried out to investigate the performance of the proposed FSS. The obtained results are discussed in depth.

This paper presents the design of an eight-element 60 GHz phased-array receiver chip with interference mitigation capability, fabricated in 0.25 μm SiGe BiCMOS technology. Each receiver element contains a low noise amplifier (LNA) and a vector-modulator that supports high-resolution amplitude and phase control. A fully differential power combining network follows the eight elements. The chip also includes an active power divider, a down conversion mixer, and fully integrated 48 GHz PLL to demonstrate the IF down-conversion. With LNA, a phase shifter and hybrid active and passive power combining network, each receiver path achieves 18 dB of gain, 360° phase shift in steps less than 3°, 20 dB amplitude control, and 4 GHz 3 dB-bandwidth and input referred 1 dB compression point P1 dB of each element is of −22 dBm. Each receiver element dissipates in total 132 mW. The phased-array receiver shows more than 25 dB of signal to interference noise ratio, by means of amplitude and phase control.

In this article, the design of a new dual-band impedance transformer with ultra-high transforming ratio (UHTR) is presented. The closed-form expressions are derived analytically using a lossless transmission-line theory. To practically validate the proposed design concept, two examples of dual-band transformer working at smaller and larger frequency ratios are designed for different load impedance of 500, 1000, and 1500 Ω. Finally, three prototypes of dual-band transformer with UHTR are designed, fabricated, and tested. For all these prototypes, different frequency ratios (two operating frequencies can be chosen arbitrarily) are considered. The measured return loss of the prototypes is better than 15 dB at all the operating frequencies. The measured results are matched very closely with the simulated results. This design is then extended to match a complex load at two different frequencies. The multi-band characteristic is obtained by decomposing a shorted stub into a stepped impedance section of the proposed structure. With the necessary derivation and analysis, a tri-frequency matching network is designed for a transforming ratio of 10.

This study investigates a low-profile circularly polarized (CP) antenna using coplanar waveguide feeding. Rectangular-shaped slots and an inverted L-shaped slit are entrenched into the ground plane to enhance the impedance bandwidth of the antenna. Furthermore, the antenna is implemented with six elliptical electromagnetic band gap structures on its substrate to enhance the −10 dB return loss bandwidth and also to generate CP waves. The experimental and theoretical results closely match each other and indicate that a simple and compact design antenna with dimensions of 0.317λ0 × 0.317λ0 × 0.023λ0(λ0 is the operating wavelength at 4.74 GHz in free space) achieves 36.9% (3.91–5.68 GHz) of the −10 dB return loss bandwidth and 9.98% (4.09–4.52 GHz) of the 3-dB axial ratio bandwidth, thus making it a favorable entrant for radio altimeter and wireless avionics infra-communication systems.

In the following, a continuous wave radar system based on the Six-port principle will be shown for measurement tasks at enclosed systems needing micrometer accuracy as well as high update rates like tank level monitoring or hydraulic cylinder piston control. To exceed the ambiguity limit of such an interferometric system, a dual tone approach is used. The system will be presented with measurement results at 24 GHz within a WR42 waveguide to prove the feasibility of the proposed concept. Furthermore, considerations on timing will show the potential as a low-latency system, capable of high measurement data update rates, and different influences on the system performance and limitations of such a system will be discussed in comparison to alternative setups.

In this paper, a novel decoupling technique for closely spaced E-plane patch antennas using defect ground structure (DGS) is proposed. The electric field coupling between the antennas is suppressed by etching DGS which consists of a pair of rectangular slots and four stubs on the ground plane. Moreover, unlike the other methods, the DGS is not etched in the middle of the antennas but loaded along the outer edge of the radiated patch. Thus, through the adopted technology the distance between the antenna elements is reduced and the isolation is increased. To validate the improvements by adopting the proposed technology, the array with DGS loading has been fabricated and then measured. The measurement results show that designed antennas have 95 MHz 10-dB impedance bandwidth, which is 25 MHz higher than that of the antenna without DGS. More importantly, isolation improvements have been increased from 8.5 to 31.3 dB by using the decoupling technique when the antennas are placed with a 0.032 λ0 edge-to-edge distance, where λ0 is the free-space wavelength. Therefore, this technique can be widely applied to improve isolation in a compact and low profile antenna system.

Triple band circularly polarized fractal boundary microstrip antenna is proposed and experimentally studied. The two orthogonal sides of the square patch are replaced with asymmetrical fractal curves for circular polarization (CP) radiation. A 45° rotated asymmetrical fractal slot is embedded at the center of the fractal patch for triband CP operation. The indentation factors of the fractal curves are optimized for better CP emission. The inserted fractal slot redistributes the current elements on the patch for triband CP radiation. The proposed antenna is implemented over a single layer with a single probe feed, so it is simple to fabricate and is cost effective when compared with the existing stacked layered multiband antennas in the open literature. The measured 3 dB axial ratio bandwidths of the proposed antenna at 2.4, 3.4, and 5.8 GHz are 2, 1, and 1.8%, respectively, so it is well suited for WLAN and Wi-MAX wireless applications.

This paper presents two J-band amplifiers in different 0.13 μm SiGe technologies: a small signal amplifier (SSA) in a technology in which never before gain has been shown over 200 GHz; and a low noise amplifier (LNA) design for 230 GHz applications in an advanced SiGe HBT technology with higher fT/fmax, demonstrating the combination of high gain, low noise, and low power in a single amplifier. Both circuits consist of a four-stage pseudo-differential cascode topology. By employing series–series feedback at the single-stage level the small-signal gain is increased, enabling circuit operation at high-frequencies and with improved efficiency, while maintaining unconditional stability. The SSA was fabricated in a SiGe BiCMOS technology by Infineon with fT/fmax values of 250/360 GHz. It has measured 19.5 dB gain at 212 GHz with a 3 dB bandwidth of 21 GHz. It draws 65 mA from a 3.3 V supply. On the other hand, a LNA was designed in a SiGe BiCMOS technology by IHP with fT/fmax of 300/450 GHz. The LNA has measured 22.5 dB gain at 233 GHz with a 3 dB bandwidth of 10 GHz and a simulated noise figure of 12.5 dB. The LNA draws only 17 mA from a 4 V supply. The design methodology, which led to these record results, is described in detail with the LNA as an example.

This paper presents the research done at LAAS-CNRS and in the context of “NANOCOMM” project. This project aims to demonstrate the potential of nanotechnology for the development of reconfigurable, ultra-sensitive, low consumption, and easy installation sensor networks with high performance in terms of reliability in line with the requirements of aeronautics and space. Each node of the sensor network is composed of nano-sensors, transceiver, and planar antenna. In this project, three-dimensional (3D) heterogeneous integration of these different components, on flexible polyimide substrate, is planned. Two types of sensors are selected for this project: strain gauges are used for the structure health monitoring (SHM) application and electrochemical cells are used to demonstrate the ability to detect frost phenomenon. After processing, sensors data are processed and transmitted to the reader unit using an ultra-wide band (UWB) transceiver. (digital baseband and radiofrequency (RF) head). The design and implementation of reconfigurable wireless communication architectures are provided according to the application requirements using nanoscale 65 nm CMOS technology. It is proposed to integrate on flexible substrate the transceiver using the flip-chip technique. A 60 GHz planar antenna is connected to the transceiver for the wireless data transmission. This paper is focused on the 3D integration techniques and the technological process used for the realization of such communicating nano-objects on polyimide substrate. The first assembly tests were carried out. Tests of interconnections quality and electrical contacts (Daisy Chain, calibration kit, etc.) were also performed with good results. A bumps contact resistance of 15 mΩ is measured.

This paper presents a very flexible tool for numerically evaluating the small-signal and noise parameters of a transmission line subject to an arbitrary thermal gradient. Contrary to previous methods, the proposed approach allows straightforwardly taking into account possible variations of electrical parameters along the propagation direction, such as may be expected when temperature ranges between very different values. The main application of the proposed method is cable modeling in noise-figure measurement setups under cryogenic operation: in such circumstances, indeed, the coaxial cables (or waveguide) at the interface between the outside and the inside of the cryogenic chamber are subject to remarkable temperature excursions. As a consequence, significant de-embedding errors may arise if the cables are not correctly modeled, given the very low values of noise figure which are commonly exhibited by cryo-cooled active devices.

In this paper, a compact, low-profile, coplanar waveguide-fed metamaterial inspired dual-band microstrip antenna is presented for Wireless Local Area Network (WLAN) application. To achieve the goal a triangular split ring resonator is used along with an open-ended stub. The proposed antenna has a compact size of 20 × 24 mm2 fabricated on an FR-4 epoxy substrate with dielectric constant (εr) 4.4. The antenna provides two distinct bands I from 2.40 to 2.48 GHz and II from 4.7 to 6.04 GHz with reflection coefficient better than −10 dB, covering the entire WLAN (2.4/5.2/5.8 GHz) band spectrum. The performance of the proposed metamaterial inspired antenna is also studied in terms of the radiation pattern, efficiency, and the realized gain. A comparative study is also presented to show the performance of the proposed metamaterial inspired antenna with respect to other conventional antenna structures in terms of overall size, bandwidth, gain, and reflection coefficient. Finally, the antenna is fabricated and tested. The simulated results show good agreement with the measured results.

This article presents the configuration and technical specification of the passive radar exploiting third-party transmitters of second-generation digital video broadcasting standard DVB-T2 as illuminators of opportunity. The performance of the two-dimensional (2D) passive radar estimated based on theoretical and experimental study is described. The possible configuration of the 2D non-equidistant antenna array for the three-dimensional (3D) passive radar is proposed to ensure the 3D localization of detected targets. The experimental results on drone detection conducted with the 3D passive radar show that the radar with the 2D antenna array is capable to measure not only azimuth but also elevation and consequently target altitude.