The paper proposes a new design for a single-arm, rectangular, spiral antenna (SARSA) with a wide azimuth space coverage. The antenna, operating at around 3.3 GHz, is capable of steering the beam in four separate directions in the azimuth plane. Only three DC signals are required to control the seven PIN diodes attached along the spiral arm. The antenna has a 200-MHz-bandwidth around 3.3 GHz with stable maximum beam directions that are defined by setting of the switches. Considerations required in selecting switch positions when designing such antennas for other frequencies, are presented. The measured return loss, radiation pattern and gain, all have close correlation with the simulation results. A detailed comparison of our design with those already proposed in the literature is given.

Several types of multiplexers based on isolation circuits have been introduced and investigated. Combining method of two filtering circuits (CMTC) is one way to make multiplexers based on isolation circuits. This method fits well for designing contiguous channel triplexers. A triplexer based on CMTC consists of a conventional transmission line (TL) connected to a diplexer and a composite right/left-handed (CRLH) TL connected to a filter. The triplexer based on CMTC has two significant advantages. One is that it is not necessary to modify the design of a stand-alone filter and diplexer and there is freedom in the choice of filtering circuits. In addition, a designer does not need to perform three-dimensional full-wave optimization, because of a simple and straightforward design concept. In this paper, a triplexer prototype having 1, 1.125, and 1.25 GHz center frequencies, is designed and fabricated. The measured results show good agreement with the simulation results.

In this paper, an optimized hyper beamforming method is presented based on a hyper beam exponent parameter for receiving linear antenna arrays using a new meta-heuristic search method based on the Firefly algorithm (FFA). A hyper beam is derived from the sum and difference beam patterns of the array, each raised to the power of a hyper beam exponent parameter. As compared to the conventional hyper beamforming of the linear antenna array, FFA applied to the hyper beam of the same array can achieve much more reduction in sidelobe level (SLL) and improved first null beam width (FNBW), keeping the same value of the hyper beam exponent. As compared to the uniformly excited linear antenna array with inter-element spacing of λ/2, conventional non-optimized hyper beamforming and optimal hyper beamforming of the same obtained by real-coded genetic algorithm, particle swarm optimization and Differential evolution, FFA applied to the hyper beam of the same array can achieve much greater reduction in SLL and same or less FNBW, keeping the same value of the hyper beam exponent parameter. The whole experiment has been performed for 10-, 14-, and 20-element linear antenna arrays.

The present paper reports the gain enhancement over a wideband (12–15 GHz) in a coplanar waveguide (CPW)-fed circular patch antenna with circular defected ground structure (DGS). Two compact coplanar circular antennas have been designed and fabricated with and without DGS of same volume 18 × 20 × 1.6 mm3, built over FR4-epoxy substrate (εr = 4.4). Gain enhancement has been achieved by optimizing the current distribution with suitable DGS. For this purpose, structural designs have been optimized by parametric simulations in HFSS and CST MWS. Both the antennas can perform well in variety of wireless communication including WLAN IEEE 802.11 g/a (5.15–5.35 GHz and 5.725–5.825 GHz) and X-band applications including short range, tracking, missile guidance, and radar communication that ranges roughly from 8.29 to 11.4 GHz. The measured experimental results show that impedance bandwidth (S11 < −10 dB) of antenna with DGS is 100%. The antenna with DGS offers gain improvement by 2.7 dB for 13 GHz and 7 dB for 14 GHz. The performance of antenna with DGS is compared to conventional CPW-fed circular patch antenna (without DGS) in terms of reflection coefficient, radiation characteristics, and gain.

We present a study on using carbon nanotubes (CNTs) as the radiating part of resonant antennas in order to reduce their dimensions. A mesoscopic electromagnetic (EM) model for CNTs was developed to allow the simulation of RF devices in classical EM solvers while retaining the specific properties of CNTs. A circuit approach is also used to provide a physical interpretation of the results on monopole antennas and trend prediction. These techniques constitute a platform to study the trends and trade-offs involved in the design of these antennas. Finally, these results are used to assess suitable fabrication techniques for CNT-based short resonant antennas and conclusions are drawn on their potential applications.

In this paper a novel approach for determining the four noise parameters of FET devices over frequency is presented. Such methodology is made of two parts: the first one allows to straightforwardly extract single-frequency noise parameters from source-pull data; the second one extends this capability to multi-frequency, source-pull data to obtain a full description of device noise behavior over frequency by means of at most 10 constant parameters (depending on the required accuracy). The whole process is automated via a software routine and does not need a previous knowledge of the FET equivalent circuit's topology, or the values of its elements. This peculiarity makes the proposed method very well suited to quick characterization campaigns of active devices, avoiding the burden of a whole set of prior, different measurements and the relevant, critical extraction procedures, which are strongly dependent on the device.

This paper presents a circuit architecture for a new integrated on chip test method for microwave circuits. The proposed built-in-self-test (BIST) cell targets a direct low-cost measurement technique of the gain and the 1 dB input compression point (CP1) of a K-band satellite receiver in the 18–22 GHz frequency bandwidth. A signal generator at the radiofrequency (RF) front end input of the device under test (DUT) has been integrated on the same chip. To inject this RF signal, a loopback technique has been used and the design has been accommodated for it. This paper focuses on the design of the most sensitive block of the BIST circuit, i.e. the RF signal generator. This circuit, fabricated in a SIGe:C BiCMOS process, consumes 10 mA. It presents a dynamic power range of 17 dB (−41; −24 dBm) and operates in a frequency range of 5.6 GHz (17.5; 23 GHz). This BIST circuit gives new perspectives in terms of test strategy, cost reduction, and measurement accuracy for microwave-integrated circuits and could be adapted for mm-wave circuits.

Combining a theory for reflection-free termination of coaxial lines together with a novel manufacturing method results in 1-mm coaxial matched loads with an excellent absorption behavior over the frequency range from 0 to 110 GHz. Three different electromagnetic (EM) simulation approaches verify the capability of these matched loads to achieve reflection coefficients smaller than −43 dB over the entire frequency range. Matched loads with a maximum reflection coefficient of only −32 dB have been produced. An excellent performance was achieved by exponentially tapering the outer conductor over the region of a coaxial ceramic substrate coated by a thin-film resistance and by compensation for EM wave propagation inside the resistive coating.

In this paper, four new wideband small antennas based on the composite right/left-handed transmission line (CRLH-TL) structures are designed, tooled, and made. The proposed antennas are introduced with best in size, bandwidth, and radiation patterns. The physical size and the operational frequency of the antennas depend on size of the unit cells and the equivalent transmission line model parameters of the CRLH-TLs, including series inductance, series capacitance, shunt inductance, and shunt capacitance. To define characteristics of the antennas, the engraved J- and I-formed voids on the radiation patches are used. The physical sizes of the CRLH antennas are 0.45λ0 × 0.175λ0 × 0.02λ0, 0.428λ0 × 0.179λ0 × 0.041λ0, 0. 564λ0 × 0.175λ0 × 0.02λ0, and 0.556λ0 × 0.179λ0 × 0.041λ0 in terms of free-space wavelengths at the 7.5, 7.7, 7.5, and 7.7 GHz, respectively. These metamaterial antennas can be used for frequency bands from 7.5–16.8 GHz, 7.7–18.6 GHz, 7.25–17.8 GHz, and 7.8–19.85 GHz for VSWR < 2, which correspond to 74.4, 82.88, 84.23, and 87.16% practical bandwidths, respectively. Also, the ranges of the measured gains and radiation efficiencies of the recommended antennas are 0.1 dBi < G < 2.1 dBi and 20% < eff < 44.3%, and 0.8 dBi < G < 2.35 dBi and 23% < eff < 48.2%, for J-shaped antennas, whereas 0.1.15 dBi < G < 3.11 dBi and 30.24% < eff < 58.6%, and 1.2 dBi < G < 3.4 dBi and 32.4% < eff < 68.1% for I-shaped antennas, respectively.

Variable Z0, a new concept in antenna design and optimization, is applied to two optimization problems: a multi-stub matching network (MSMN) using biogeography-based optimization (BBO), and an ultra wideband meander monopole antenna (MMA) using central force optimization (CFO). BBO is a newly-proposed stochastic global search and optimization evolutionary algorithm (EA) used to determine MSMN stub lengths and locations for optimum (minimum) reflection coefficient. CFO is a deterministic EA used to optimize the MMA's impedance bandwidth (IBW) while maintaining good average gain without considering the radiation pattern in detail. Two cases are investigated for both problems: (a) fixed characteristic impedance Z0, and (b) variable characteristic impedance. In the first case, Z0 is a fixed user-specified parameter (the traditional methodology), whereas in the second, it is a true variable quantity whose value is determined by the optimization methodology, which is a new technology. Variable Z0 is a fundamentally different design approach in optimization problems. BBO's fixed Z0 results for MSMN are compared to published data computed using Nelder–Mead optimization with BBO exhibiting better performance. BBO's results are improved even more using Variable Z0 technology. A similar performance improvement is seen for Variable Z0 applied to the CFO-optimized MMA.

An active receiving antenna for Radio Navigation and Radio Positioning applications in S-band frequency is designed and fabricated. In this active antenna, the amplifier is integrated with the radiator which is a rectangular patch antenna. This patch antenna is analyzed with full-wave momentum method. With the developed design routine, ultra-low noise active receiving antenna can be realized. The ADS software and its full-wave Momentum is used for simulation. The experimental results show good agreement with the simulation results.

An accurate and very large band (30–110 GHZ) lumped element equivalent circuit model of capacitive RF-MEMS components based on a standard 250 nm BiCMOS technology is presented. This model is able to predict the effect of the fabrication process dispersion, synthesize new components and monitor the failure mechanisms. Moreover, a reliability study is performed in order to define a screening criterion (VPOUT > 36 V and |VPIN − VPOUT| ≤ 1) based on which a selection of the devices with optimal performance in terms of RF and lifetime performance can be made. Finally, a very quick effective technique (non-intrusive) is proposed to carry out this operation.

Two compact resonant near-field sensors are introduced for the characterization of aqueous solutions at 5 GHz. They are based on folded substrate-integrate circular half-mode resonators with a planar sensing tip. Owing to the planar design, the sensor is simple and cheap to manufacture, and a sample can be easily coupled to the resonator from the top. The operating principle of the sensor is explained and verified by both simulation and measurement. The radiation of the sensors is quantified by means of a quality factor analysis. Finally, a previously introduced calibration method based on the perturbation theory is applied to the sensors and its accuracy is improved by choosing more suitable reference materials.

Three-dimensional compact volume internal antenna for universal serial bus (USB) dongle that covers hexa operating bands is proposed in this paper. The volume of the proposed USB dongle is 15×20×4 mm3; it is based on two connected monopoles, one of them is semi-circular monopole ended by three unit cells of meander-line and the other is a bent monopole with four unit cells of high-impedance wire. The proposed antenna is realized on a printed circuit board to reduce the fabrication costs. The coupling between the antenna elements broadens the operating bandwidth, which includes most of the wireless commercial service bands, GSM850/GSM900/UMTS/GSM1800/GSM1900/WCDMA2100/802.11b/g/LTE2600 (824–2690 MHz) as well as 802.11a/n (5150–5825 MHz). The antenna's simulated and experimental results are in good agreement.

In this paper, the design methodology of a flat reflector composed with standard dielectric material and using transformation electromagnetics (TE) is presented. First, the mathematical relation between a flat reflector and a parabolic one is described. The TE principle is then described. Some realization issues are highlighted, leading to approximations and compromises in order to design a more realistic structure. In this way, a flat reflector made only with standard dielectric materials is presented, using an original method to achieve the desired spatial permittivity variation. The simulation results of different configurations for the flat reflector are presented and compared to classical solutions in order to prove the thickness reduction and the improvement of radiation characteristics in terms of gain and half-power beamwidth.

The orthogonal LSM10 and TE10 modes that are supported by the image SINRD (iSINRD) guide and substrate integrated waveguide (SIW) is exploited to develop a planar millimeter-wave hybrid orthogonal-mode transducer (OMT) within the same dielectric substrate. The two output arms are iSINRD guide and an SIW. The proposed co-layered planar OMT belongs to a narrowband acute angle class. The design process is explained and measurements at 94 GHz are presented. No septa or step changes in thickness are required. Both modes are excited using WR10 transitions, where the transition of one mode is orthogonal to the other. Therefore, the OMT is fabricated as a back-to-back 4-port OMT; two inputs and two outputs for each mode respectively. The lateral dimensions of all guiding arms are 0.6 × 0.635 mm2. An insertion loss of around 1.2 dB is obtained for both LSM10 and TE10 modes, while isolation better than 17 dB is obtained for both modes (30 dB for the LSM10 mode).

In this paper, the design analysis of a multi-way and high-power radial combiner is presented. This combiner incorporates a rigid stripline-type combining structure. This analysis, based on an equivalent circuit model and segmentation of the radial transmission line, provides simple design formulae. The developed methodology, after fine-tuning with the help of an electromagnetic full-wave simulator, is physically demonstrated by developing a high-power (16 kW average) and high combining-efficiency (98.9%) 16-way combiner at the center frequency of 505.8 MHz. Its efficient and repeatable performance, fabrication-friendly structure, and absence of the heat-related problem, caused by the isolation resistor, are the main features of this design.

This paper presents a simulation approach of optical heterodyne systems by using the equivalent circuit representation of a distributed feedback laser (DFB) in the electrical domain. Since the electrical representation of the DFB laser is developed from the rate equations, its characteristics such as non-linearity, relative intensity noise (RIN), and phase noise can be predicted precisely for various biasing conditions. The model is integrated in a heterodyne radio over fiber (RoF) system where two DFB lasers are used to generate a millimeter-wave (mm-wave) signal. An optical phase-locked loop is also introduced to reduce the phase noise on the mm-wave signal. The optical phase noise contribution of individual lasers to the mm-wave signal is evaluated and compared with theoretical results. It is shown that the phase noise of the mm-wave is reduced considerably depending on the loop bandwidth and propagation delay. With the circuit simulation approach proposed, optical and mm-wave phase noises can be studied together with other circuit environments such as parasitic effects and driver circuits.

A comparative analysis of radiated power in relativistic magnetron is done using particle-in-cell simulations performed on Magic3d code developed by ATK Mission Systems. The Resonator with dielectric side-walls (DSW) is compared with no-side wall (NSW) configuration having same input parameters and resonator dimensions. Observations and comments have been made on the output power, obtained both axially and radially, taking into consideration π as well as 2π modes of operation for both configurations. The DSW assist in π-mode operation at 3.3 GHz and delivers radial peak power output of ~2.5 GW, which is more than ~1.5 GW, the radial peak power for the NSW case. The NSW case operates in dominant 2π mode (radially) at 5.68 GHz with axial power radiated at dominant π-mode frequency. The electron kinetic energies and their distribution in the cavity are discussed together with the dynamic behavior of particles, which result in spokes formation.

This proposed work illustrates the design of a defected ground structure (DGS)-based coplanar waveguide (CPW)-fed multiband microstrip antenna consisting of four vertical monopoles, joined together by the few rectangular horizontal strips. In this multiband antenna, I-shaped defects are inserted into both sides of ground plane of CPW feed creating a DGS-CPW. The 10 dB impedance bandwidth of lower band is 29%, ranging from 2.232 to 3.1 GHz, with respect to the central frequency of 2.52 GHz, and while that of the upper band is 2.1 GHz (4.712–6.81 GHz), about 35%, referred to the central frequency of 5.7 GHz. The parametric study is performed to understand the characteristics of the proposed antenna. To verify the simulated design concept, a prototype antenna is designed and fabricated on the FR4 substrate, and characterized experimentally. The characteristic of antenna parameters such as S-parameter, gain, current distribution, and radiation pattern have been studied. The proposed antenna is suitable for WLAN/WiMAX applications.