A new circularly polarized planar array antenna using linearly polarized microstrip patches is designed and optimized for X-band wireless communication applications. Four square patch elements with feed network are used to design the circularly polarized array antenna. The feed network consists of microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. Both-sided MIC technology is successfully employed to apply its inherent advantages in the design process of the array structure. The unequal feed line is used to create 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Characteristics of the proposed array are investigated by using two electromagnetic (EM) simulators: advanced design system and EMPro. The −10 dB impedance bandwidth of the antenna is around 5%. The 3 dB axial ratio bandwidth of 1.48% is obtained. The design of the proposed antenna along with parametric study is presented and discussed.

In this paper, a new antenna has been proposed with dimensions of 28 × 28 × 0.8 mm3 and the ability of operating in ultra-wideband (UWB) frequency and switching three notched bands. In the structure, to achieve the removal of characteristic of three frequency bands, a rectangular patch with an H-shaped slot on its surface and two C-shaped arms on its sides have been used. In addition, the designed antennas have the ability of operating in five different modes. To achieve the performance of reconfiguring, three pin diodes are used on the slots of rectangular patch and those two C-shaped arms. Also, with the defect ground structure and creating two rectangular slots and two L-shaped slots on the ground plane we make the excite of additional resonances and thus increase antenna bandwidth. Simulation and measurement results show that the designed antenna is able to cover the range of frequencies 3–12 GHz and a controllable frequency band rejection in the three frequency bands 3.2–3.75 GHz (WiMAX), 5.05–5.9 GHz (WLAN), and 8–8.45 GHz (ITU). The proposed antenna decreases the interference of the mentioned wireless systems with the UWB frequency.

This paper presents design, fabrication, and testing of a palm tree structured monopole antenna for wideband applications. The proposed antenna has a wide impedance bandwidth (−10 dB bandwidth) from 4 to 10.4 GHz. Palm tree antenna of compact size 23 mm × 20 mm is designed and fabricated on an FR4 substrate of thickness 1.6 mm. To validate the design, a mathematical relationship between the parameters of the palm tree geometry and the lower cut-off frequency has been established. Parametric study has been carried out to obtain optimum wideband characteristics. The prototype is experimentally validated for the band 4–10.4 GHz within ultra-wideband operations. Transfer function, impulse response and Group delay has been plotted in order to address the time domain characteristics of the palm tree antenna with fidelity factor values. The possible applications cover 5.2–5.8 GHz WLAN, C-band operations, 5.5 GHz WiMAX, and Wireless USB.

This paper presents and discusses several methods for predicting the low-frequency (LF) noise at the output of a mm-wave detector. These methods are based on the extraction of LF noise source parameters from the single diode under a specific set of bias conditions and the transfer or conversion of these noise sources, under different operating conditions including cyclostationary regime, to the quasi-dc output of a mm-wave detector constructed with the same model of diode. The noise analysis is based on a conversion-matrix type formulation, which relates the carrier noisy sidebands of the input signal with the detector output spectrum through a pair of transfer functions obtained in commercial software. Measurements of detectors in individual and differential setups will be presented and compared with predictions.

This paper presents the design of a fully integrated ultra-low-power Ultra Wide Band (UWB) pulse generator. The circuit is designed and optimized for low rate and localization applications. This UWB transmitter is based on the impulse response filter method in order to achieve high energy sub-nanosecond pulses. The circuit has been integrated in a ST-Microelectronics CMOS 0.13 μm technology with a supply voltage of 1.2 V on a die area of 0.56 mm2. A power manager is used to reduce the power leakages to 3.91 μW which gives a power consumption of 3.98 Mw at 10 kb/s. The measured dynamic energy consumed per pulse is 68 pJ and the measured energy of the emitted pulse is 2.15 pJ.

A compact asymmetric coplanar strip (ACS)-fed monopole antenna for dual-band application is presented. The single-layer antenna composed of inverted L-shaped exciting strip and an L-shaped lateral ground plane. The antenna resonating at two different frequencies, 2.4 and 5.8 GHz is covering the wireless local area network/radio frequency identification bands. The antenna has an overall dimension of 35 × 5.7 mm2 when printed on a substrate of dielectric constant 4.4 and loss tangent 0.02. The planar design, simple feeding, and compactness make it easy for the integration of the antenna into circuit boards. Details of the antenna design, and simulated and experimental results are presented and discussed. The experimental result shows good conformity with simulated results. The simulation tool based on the method of moments (Mentor Graphics IE3D version 15.10) has been used to analyze and optimize the antenna.

This paper presents a compact broadband printed monopole antenna with U-shaped slit in the partial ground plane and rectangular parasitic patches adjacent to the microstrip line for multiple applications. The optimal dimensions of the proposed antenna are 35 × 25 × 1.5 mm3 and is fabricated on commercially available low-cost FR4 substrate with εr = 4.3 and 0.025 loss tangent. Due to introduction of rectangular parasitic patches and U-shaped slit large bandwidth has been achieved. The impedance bandwidth (return loss, magnitude of S11 < 10 dB) of the proposed antenna is 139% (2.9–16.3 GHz). The proposed antenna covers ultra wide band applications, 5.2/5.8 GHz WLAN bands, 3.5/5.5 GHz WiMAX bands, X band (8–12 GHz), satellite communication, and other wireless communication services. The study shows that there is good agreement in simulated and measured results. Nearly stable radiation patterns have been obtained throughout the operating band. Antenna results and details are discussed and elaborated.

An engineered novel tunable dual-band metamaterial antenna based on stacked split ring resonator (SRR) array is presented. The μ-negative SRR array present at two sublayers of stacked microstrip patch antenna substrate adds tuning capability to the antenna with marginal trade-off between antenna gain and cross-polarization. If the size of resonator element is considerably smaller than resonance wavelength, ideally lesser than λ/10, the resonator would support the resonating mode of antenna. Compact SRR array embedded in radiator facilitate the antenna tuning to intended allocated spectrum of L5- and S-band frequencies without modifying external dimensions of patch antenna, which in turn helps the satellite payload design. The variations in SRR array dimensions and inter-element spacing are subsequently utilized to maintain the antenna gain and voltage-standing wave ratio. The proposed design of inset fed antenna, matched at 50 Ω, was validated by experimental results and it is suitable for global positioning satellite applications.

In this paper, a dual wideband microstrip antenna (MSA) has been presented for wireless local area networks (WLAN), worldwide interoperability for microwave access (Wi MaX) and U-NII band applications. The antenna is designed and simulated using CSTMWS V'10. The main goal of this paper is to get multi-frequency behavior by cutting resonant slots into the patch of the antenna and a wideband antenna behavior using an aperture coupled feeding method. The designed antenna has a semi-spiral G-shaped compact structure and an electromagnetically coupled feeding mechanism (aperture-coupled feeding). It is fabricated on an FR4 substrate with a dielectric constant of 4.4 and a dielectric loss tangent of 0.009. The testing of prototype antenna (to measure S11) is done using a vector network analyzer. The measured results are 80% matching to the simulated ones. The parametric study, simulation results, measured results, and applications of the MSA for WLAN, WiMAX, and the FCC unlicensed 5.2 GHz National Information Infrastructure (U-NII) bands are presented in the paper. The antenna shows a simulated gain of about 4.5 dB at the three wireless application bands.

A wideband orthogonally slot cut annular ring microstrip antenna fed by L-shaped probe is investigated using modal expansion cavity model and circuit theory approach. Simulation of the proposed antenna is performed using Ansoft HFSS and simulated results are compared with the measured and theoretical results. The impedance bandwidth of about 37.46% is observed at resonant frequency 3.15 GHz. The proposed antenna realizes an improvement in bandwidth of 13.46% and miniaturization in physical dimension about 10% from earlier reported structures. An improvement in bandwidth and miniaturization is due to thick substrate, L-probe feed, and orthogonally loaded slots. The measured results of fabricated antennas are in good agreement with simulated and theoretical results.

A novel antenna-harvester co-design paradigm is presented for wireless nodes operating in an Internet of Things context. The strategy leads to compact and highly-integrated units, which are able to set up a reliable and energy-efficient wireless communication link, and to simultaneously harvest energy from up to three different sources, including thermal body energy, solar, and artificial light. The core of the unit consists of a substrate-integrated-waveguide (SIW) antenna. Its surface serves as a platform for the flexible energy-harvesting hardware, which also comprises the power management system. To demonstrate the approach, two different SIW cavity-backed slot antennas and a novel compact dual linearly polarized SIW antenna are presented. These topologies facilitate the integration of additional hardware without degrading performance. In the meantime, they enable comfortable integration into garments or unobtrusive embedding into floors or walls. Measurements on prototypes validate the integration procedure by verifying that the integrated hardware has a negligible influence on the performance of all discussed SIW antennas. Finally, measurements in four well-chosen indoor scenarios demonstrate that a hybrid energy-harvesting approach is necessary to obtain a more continuous flow and a higher amount of scavenged energy, leading to a higher system autonomy and/or reduced battery size.

In this paper, a novel design of compact wideband multiple-input multiple-output (MIMO) antenna operating over a frequency range of 1.8–4.0 GHz at 10 dB is presented for mobile terminals. The MIMO antenna design consists of two symmetrical and orthogonal radiating elements with a small size of 15.5 × 16.5 mm2 printed on the corners of a mobile circuit board. The radiating element is composed of four meandered monopole branches with a strip-line fed by a probe. By triangularly trimming the corners of the common ground plane beneath the radiating elements, not only the mutual coupling is reduced, but also impedance bandwidth is increased. Although, the antenna in this form has sufficient correlation level between the radiating elements for MIMO operation, a novel design of plus-shaped parasitic element is inserted to the ground plane between those radiating elements in order to further enhance the isolation. The performance of the MIMO antenna is investigated in terms of s-parameters, radiation pattern, gain, envelope correlation coefficient (ECC), and total active reflection coefficient (TARC), and is verified through the measurements. The results demonstrate that the proposed MIMO antenna has good characteristics of wideband, isolation, gain, radiation pattern, and is compatible with LTE, WiMAX, and WLAN, besides it is small, compact, and embeddable in mobile terminals.

In this paper, a novel circularly polarized square slot microstrip antenna is proposed for radio frequency identification (RFID) applications. The circular polarization is achieved by incorporating an arc-shaped strip in the square slot antenna. This antenna is fed by deformed bent feeding line to achieve a broad bandwidth (BW). The key parameters of the antenna are used for parametric study to understand the influence on the antenna performance. To validate simulation results of the design, a prototype is fabricated on the commercially available FR4 material. Measured results show a good agreement with the simulated results. It is found that the antenna shows an impedance BW of 170 MHz (844–1014 MHz) and axial-ratio BW of 170 MHz (834–1004 MHz), which shows that the proposed antenna is a good candidate to be used as a RFID antenna.

This paper presents a full-duplex dual-band orthogonal frequency division duplexing (OFDM) radio architecture that enables the radio transceiver to be more flexible and provides a viable radio link capacity gain. A simple but practical I/Q imbalance estimation and compensation method, based on the frequency-flat-fading behavior of the self-interference channel, is proposed. The performance of the proposed I/Q imbalance compensation method is evaluated by link level simulation conducted with Advanced Design System and Matlab. The co-simulation results show that the proposed radio transceiver could potentially increase the physical layer transmission rate by four times compared with the conventional radio link at the cost of tolerable loss of bit error rate performance. The I/Q imbalance compensation method can effectively compensate both high and low I/Q imbalance without the problem of algorithm convergence.

This paper presents a simple broadband planar monopole microstrip patch antenna with curved slot and partial ground plane. The proposed antenna is designed and fabricated on commercially available FR4 material with εr = 4.3 and 0.025 loss tangent. Bandwidth enhancement has been achieved by introducing a curved slot in the patch and optimizing the gap between the patch and the partial ground plane and the gap between the curved slot and the edge of the patch. Simulated peak gain of the proposed antenna is 4.8 dB. The impedance bandwidth (defined by 10 dB return loss) of the proposed antenna is 109% (2–6.8 GHz), which shows bandwidth enhancement of 26% as compared with simple monopole antenna. The antenna is useful for 2.4/5.2/5.8-GHz WLAN bands, 2.5/3.5/5.5-GHz WiMAX bands, and other wireless communication services. Measured results show good agreement with the simulated results. The proposed antenna details are described and measured/simulated results are elaborated.

Traditional near-field antenna measurements use the sampling theorem to reconstruct the antenna pattern perfectly. However, a large number of measurement points are required for this approach. To address this problem, in this study, we propose a technique to accelerate the near-field antenna measurement, which is achieved by sparse E-field sampling in the region where the E-field changes smoothly and dense sampling in the region where the field changes rapidly. Further, our approach ensures robustness of measurement; the E-field information need not be known before carrying out measurements. Our experimental results demonstrate that our technique can reduce the number of measuring points by at least 64.9% when measuring two different patterns (15-GHz horn antenna with θ = 0° and 10°).

A novel compact asymmetric coplanar strip fed planar antenna with defected ground structure and defected microstrip structure for dual band application is presented. The proposed antenna is composed of defect in both ground plane and radiating strip. The antenna has an overall dimension of 21 × 15.35 × 1.6 mm3 when printed on a substrate with dielectric constant of 4.4 and loss tangent of 0.02. The antenna resonating at two different frequencies of 3.5 and 5.5 GHz is covering worldwide interoperability microwave access and wireless local area network bands. The planar design, simple feeding technique, and compactness make it easy for the integration of the antenna into the circuit board. Details of the antenna design, simulated, and experimental results are presented and discussed. Simulation tool, based on the method of moments (Mentor Graphics IE3D version 15.10) has been used to analyze and optimize the antenna.

Asymmetric slits loaded irregular shaped microstrip patch antenna with three different ground structures is proposed. All three antennas show triple band characteristics. First antenna with regular ground plane resonates at 1.95, 2.4, and 4.90 GHz with good radiation characteristics and shows right-hand circular polarization at 1.95 GHz. 18.75% of compactness is achieved with triple band characteristics. Further, same patch is used with different defected ground structures. Second antenna resonates at 1.85, 2.4, and 4.85 GHz with suppressed cross-polarization level and antenna shows right-hand circular polarization at 1.85 and 4.85 GHz. Compactness is further improved to the value of 22.91%. The third antenna resonates at 1.95, 2.4, and 4.85 GHz with better gain and radiation characteristics and antenna shows right-hand circular polarization at 1.95 and 2.4 GHz. The small frequency ratio f2/f1 is achieved and the value of f2/f1 is 1.29 and 1.23 for second and third configuration, respectively. Proposed structures show right-hand circularly polarized with suppressed left-hand circularly polarized radiations and suitable for fixed mobile wireless communication applications. All structures are analyzed using Ansoft HFSS v.14 based on finite element method and measured results satisfy the simulated results.

A novel compact multiple-input–multiple-output (MIMO) antenna system operating from 5 to 7.3 GHz is proposed for wireless applications. It comprises of two similar antennas with microstrip feeding and radiating patches developed on a reduced ground plane. The developed antenna system resonates at a dual-band of 5.4 and 6.8 GHz frequencies, giving an impedance bandwidth of 38% (based on S11 < −10 dB). The unique structure of the proposed MIMO system gives a reduced mutual coupling of −27 dB at 5.4 GHz resonant frequency and −19 dB at 6.8 GHz resonant frequency and in the entire operating band the coupling is maintained well below −16 dB. The envelope correlation coefficient of the proposed MIMO system is calculated and is found to be less than 0.05 in the operating band. The measured and simulation results are found in good agreement.

In this paper, the influence of tree trunks, cylindrical street furniture such as lamp posts, and traffic on ray tracing simulations in an urban scenario is analyzed. Tree trunks and lamp posts are modeled by cylinders and propagation characteristics computed according to the Uniform Theory of Diffraction. The influence of traffic is analyzed by simulations with moving vehicles. In order to get an understanding of the spatial characteristics of the channel, simulations with static and also mobile receivers have been performed, in line with a measurement campaign in the same environment. The simulation results show a good agreement with the measurements.