Microwave Engineering, Electromagnetics, High Frequency Techniques

A method is presented in this paper for the design of a high frequency CMOS operational amplifier (Op-Amp) which operates at 3V power supply using tsmc 0.18 micron CMOS technology. The OPAMP designed is a two-stage CMOS OPAMP followed by an output buffer. This Operational Transconductance Amplifier (OTA) employs a Miller capacitor and is compensated with a current buffer compensation technique. The unique behaviour of the MOS transistors in saturation region not only allows a designer to work at a low voltage, but also at a high frequency. Designing of two-stage op-amps is a multi-dimensional-optimization problem where optimization of one or more parameters may easily result into degradation of others. The OPAMP is designed to exhibit a unity gain frequency of 2.02GHz and exhibits a gain of 49.02dB with a 60.5 0 phase margin. As compared to the conventional approach, the proposed compensation method results in a higher unity gain frequency under the same load condition. Design has been carried out in Tanner tools. Simulation results are verified using S-edit and W-edit.

Microwave/gelombang mikro merupakan pengiriman sinyal radio dengan frekuensi sangat tinggi pada dua buah relay station (stasiun pengulang) yang tidak terhalang satu sama lain. Pada gelombang mikro, kisaran frekuensinya dari 1 GHz sampai 300 GHz. Propagasi/perambatan gelombang pada kisaran frekuensi ini adalah propagasi line of sight (LOS).

International Journal of Microwave Engineering (JMICRO) is a peer-reviewed, open access journal which invites high quality manuscripts that focuses on Engineering and theory associated with microwave / millimeter-wave technology, guided wave structures, electromagnetic theory and implementation. Authors are invited to submit original research works that stimulate the development of latest technology in industry and academia. Good quality review papers and short communications are also acceptable. Research areas suitable for publication include, but are not limited to the following fields:

The radio refractive index structure of the lower section of the atmospheric boundary layer is critical in the planning and construction of microwave communication connections. This study analyses the refractivity profile carried out in Mowe (6.8085° N, 3.4367° E) SouthWestern Nigeria. Ground measurements of air pressure, temperature, and relative humidity used in this investigation were collected from the rain gauge of the Tropospheric Observatory Data Acquisition Network (TRODAN). The radio refractivity, associated refractivity gradient and climatic factor were computed using data from January 2012 to December 2013. The vertical distributions of radio refractivity were then calculated using these parameters. Seasonal fluctuations in refractivity are visible over the location, with high values in the wet season and low values in the dry season. The findings also suggest that propagation circumstances fluctuate in frequency, with sub-refractive situations being most common between April and September. This is an indication that microwave link in Mowe will suffer higher signal loss during wet season, while the loss may be mild during the dry season. The refractivity values in this study are expected to aid in determining the necessary mitigation to be put in place to reduce loss of signal in Mowe.

A common problem found in high-speed communication is inters-symbol interference (ISI).This occurs when a transmission interferes with itself, and the receiver cannot decode the transmission correctly. Because the signal reflects from large objects such as mountains or buildings, the receiver sees more than one copy of the signal. This is what is referred to as multipath. Since the indirect paths take more time to travel to the receiver, delayed copies of the signal interfere with a direct signal causing (ISI).To avoid ISI due to multipath, successive OFDM path, successive OFDM symbols area separated by the guard band. Orthogonal frequency division multiplexing is mainly designated to combat the effect of multipath reception.

The design of circularly polarised multiband poly fractal boundary microstrip antenna is proposed and experimentally studied. Initially the two orthogonal sides of the square patch are replaced with different fractal curves for circular polarisation (CP) radiation. Along the x and y axes, Minkowski and Koch fractal curves are employed. A 45° rotated poly fractal slot is embedded at the center of the fractal patch for triband CP operation. The indentation depths and indentation angles of the Minkowski and Koch fractal curves are optimised for better CP emission. The inserted fractal slot redistributes the current elements on the patch for tri band CP radiation. The measured 3-dB axial ratio bandwidths of the proposed antenna at 2.4 GHz, 3.4 GHz, and 5.8 GHz are 1.53 per cent, 0.81 per cent, and 1.62 per cent respectively, making it an able candidate for WLAN and Wi-MAX wireless applications.

The realization of a software-defined radio has been a particular objective of the military industry and academia in Turkey. Broadband frequency-tunable PAs and matching networks [28], [29] (see Figure 2) were designed at METU–Northern Cyprus Campus’s RF and Telecommunication Laboratory (established by Dr. Tayfun Nesimoglu [30]) using RFT [8]–[18].

In 1918 Albert Einstein wrote in a letter to Walter Dällenbach against his own theory of optical force: “It has long been known that the values I had derived with Laub at the time are wrong; Abraham, in particular, was the one who presented this in a thorough paper. The correct strain tensor has incidentally already been pointed out by Minkowski”. Unfortunately after almost 100 years, it is still not clear why Einstein wrote so regarding the theory of optical/electromagnetic force (the optical stress tensor (ST)) associated with Lorentz force. The electromagnetic force is one of the four fundamental interactions (other three: the strong interaction, the weak interaction and gravitation) in nature. In spite of experiencing much progress from 1970, research on optical/electromagnetic forces has so far revealed only the partial nature of light-matter interaction. For example, inside a material media an appropriate description of photon momenta (i.e. the Abraham-Minkowski dilemma) and an appropriate description of stress tensors along with Lorentz /volumetric forces (known as Minkowski, Abraham, Chu, Einstein-Laub and Ampere/Nelson forces) are still matters of great controversy. In this thesis, physics and applications of Lorentz force along with stress tensors and photon momenta have been investigated in details with special interest in tractor beam effect, plasmonic objects, chiral objects and the objects embedded in a generic material medium. At first, we have considered simpler case: application of Lorentz force for the objects placed in air. Specifically we demonstrate how the mechanism of Lorentz force can be used in a tractor beam-like effect for pulling multiple Rayleigh particles placed outside a dielectric hollow core waveguide and coupler. We also represent the Lorentz force analysis for plasmonic off-axis and on-axis spherical heterodimers and it is shown that the reversal of longitudinal binding force can be easily controlled by forced symmetry breaking. Though it is commonly believed that plasmonic forces mostly arise from the surface force and Fano resonance can be a promising way to achieve binding force reversal, our study based on Lorentz force dynamics suggests notably opposite proposals for the case of plasmonic spherical heterodimers. Next, we have also considered objects those are embedded in a material medium. The fundamental results/proposals of this thesis are presented afterwards. We have shown that the well-known Lorentz force leads to inconsistent result (pushing force) instead of the experimentally observed optical pulling force as observed in interfacial tractor beam experiments. As one of the major contributions of this thesis, we identify the ‘exact’ reasons why the well-known distinct Lorentz/volumetric forces fail not only for interfacial tractor beam experiment but also for several other major radiation pressure experiments performed up to date. Later, we demonstrate that it is still possible to establish different equivalent time-averaged Lorentz / volumetric force formulas based on the fulfilment of just two ‘consistency conditions’. Based on those proposed ‘consistency conditions’, finally, we demonstrate that by modifying the Einstein-Laub or Chu formulation; time-averaged STs and volume forces are obtainable, which can overcome the aforementioned inconsistencies. For example- these modified formulations can yield the ‘correct’ time averaged force similar to Minkowski’s force for almost all the previous real experiments. Specially, our proposed modified Einstein-Laub ST can be considered as an efficient mathematical toolkit, an alternative of time and memory consuming volumetric forces, to yield the internal bulk force of a chiral or achiral object embedded in complex material backgrounds (i.e. homogeneous, heterogeneous, bounded etc.). Later, we have also shown an interesting application of modified Lorentz force to control the reversal of optical binding force of plasmonic cubes placed over plasmonic substrate due to strong Fano resonance. Finally, based on our proposals throughout the thesis, at the end of this thesis we propose a new hypothesis named as the ‘existence domain’. ‘Existence domain’ is the region either outside of a scattering body taking only its exterior fields into account, or in its interior considering only the inside fields. Though almost all the time averaged distinct STs and volumetric force laws are restricted to the idea of ‘existence domain’, we demonstrate that the stress tensor, volumetric force and photon momentum of Minkowski are free from such and other restrictions both in instantaneous and time averaged situations. After almost 100 years of Einstein’s prediction, this thesis, most probably, finally answers why only Minkowski’s theory of optical force and photon momentum remains consistent in all circumstances. Proposals presented in this thesis can be very effective for resolving not only the dilemma of distinct stress tensors and optical Lorentz/ volumetric forces but also for settling the controversy of Abraham-Minkowski photon momenta. This thesis may also open a new window for optical pulling force/tractor beams along with the novel manipulation process of plasmonic dimers.

"This paper describes several radio frequency interference shields that have been developed for integration with high-speed bulk-input turret-test IC handlers. The shields were developed to mitigate interference to noise figure measurements of Low Noise Amplifier components. Two categories of shielded enclosures were evaluated for shielding effectiveness and ease of incorporation into the existing machines and manufacturing processes. The first category enclosed the handler's working area in its entirety, while the second one enclosed the testboard only. Variation in the testboard shield design was required to suit different collet trajectories between handler models. The shielding effectiveness (SE) was measured according to the MIL-STD-285 standard. The different designs exhibited SE in the 16-49 dB range.

Index Terms —  RF shielding, electromagnetic screening, noise figure measurement."

This article reviews the development and applications of harmonic injection technique. It discusses the impact of second harmonic injection on the linearity and linear gain of amplifiers. It reveals that amplifier characteristics and input drive level determine whether second harmonic injection enhances or reduces the linear gain of an amplifier. Furthermore, a method has been developed to predict this behaviour which can be used to identify amplifiers that are best suited to harmonic injection or build amplifiers that may particularly be used with harmonic injection. For experimental investigation, a second harmonic injected amplifier was used that employs a frequency-doubler. In laboratory experiments, third-order intermodulation distortion was suppressed by 18 dB at the expense of 0.7 dB linear gain whereas theoretical analysis has predicted that second harmonic injection could compromise the linear gain of the amplifier by up to 1.3 dB for 20 dB distortion suppression.

"The main cause of loss in the PIN-Schottky limiter is the diodes’ parasitic capacitances. Techniques to counter the parasitic capacitances include using bare chip, air cavity packaging, diode stacking, mesa construction, isolating the Schottky diode from the signal path and connecting the diodes to a low impedance node. But the aforementioned techniques either sacrifice cost, manufacturability, size, performances or thermal ruggedness. To reduce loss in the PIN-Schottky limiter, we re-configured its parasitics into a low pass ladder network. This paper reports on the new configuration’s changed large signal and transient performances. We observed improved isolation at 0.9 and 2.4 GHz, and a beneficial reduction in the initial energy that slips through the limiter before limiting begins. In conclusion, this configuration simultaneously improves insertion loss, matching, isolation and spike leakage suppression. It has the potential to improve limiting performances in wideband receivers for wireless communication and medical imaging.
Index Terms — Limiter, receiver protection, Schottky assisted PIN limiter, Schottky enhanced PIN limiter, quasi-active limiter."

A finite-element scheme for solving wave propagation problems in devices with complete az­imuthal symmetry both in their material properties and geometry is presented. The ¢-coordinate varia- •
tion is restricted to sin(n,f, + e), thus requiring only a two dimensional space for the complete finite-element analysis. The open radiating boundaries inherent in many propagation problems are tackled through sim­ulated absorption of the radiation by lossy materials. Also proposed for these kinds of boundaries is a hybrid FEM-BEM formulation, based on the vector Green's function for the Helmholtz equation.This method has been tested by application to an open-ended circular waveguide and a comparison with the simulated­absorption results.

The trade-off between efficiency and tunability has been revealed in frequency-tunable amplifiers. Several tunable amplifiers have been designed using various varactor diode topologies and their performances are compared. Simulation results demonstrate that the tunable amplifiers using anti-series distortion-free varactor stack (DFVS) topologies provide superior tunability and power added efficiency (PAE) than those using conventional varactor diode topologies. A tunable amplifier is designed that can tune from 1.74-to-2.36 GHz and provide 42% PAE. This range of tunability is sufficient to accommodate DCS-1800, PCS-1900, DECT and UMTS standards, and thus it may help to reduce the complexity of multimode and reconfigurable radios.

Second harmonic zone (SHZ) injection is a feedback technique for reducing the intermodulation distortion (IMD) at the output of an amplifier, which is based on feeding the SHZ intermodulation products (IMP), back to the amplifier's input. The technique is analyzed theoretically and practical results demonstrate the linearisation performance. Two feedback prototypes were built, one using a frequency doubler and the other using a buffer amplifier as a distorter, where 14 dB and 13 dB improvement was obtained respectively in reducing the third order IMP (IMP3). The performance of the technique with changing frequency and input power level was also investigated

We demonstrate that a frequency-independent parallel RC circuit is the simplest model that accurately describes high-frequency electrical conduction in 1-D nanostructures. The resistance is determined from dc measurement, and the capacitance is extracted directly from the measured S-parameters for a ground-signal-ground test structure, without using any fitting parameter. The methodology is applied to carbon nanofibers, and the RC model yields results that are within ??0.5 dB and ??5?? of the measured S-parameters up to 50 GHz. The model is further justified by examining the relationship between S- and Y-parameters of the test network.

"This paper describes a Quad Flat Non-lead (QFN 2x2) packaged PIN diode switch that is capable of handling Continuous Wave (CW) power up to 40W and WCDMA signal up to 10W. The target application is the Transmit (Tx) arm of a Transmit Receive (TR) switch for cellular base-stations. The part was developed in response to this market segment's aggressive cost-cutting pressure. Prior designs relied on more expensive ceramic packages.

Index terms: high power PIN diode switch, low cost PIN diode switch, compact PIN diode switch"

This paper reviews the state-of-the-art in microwave technology by investigating the most important elements of transceivers. It identifies the enabling technologies and research areas in radio frequency engineering that may facilitate the development of Software Defined Radios. Receiver architectures are also discussed and their viability for a reconfigurable radio application is investigated. The design of tunable radio frequency components, linear and power efficient amplifiers as well as linear mixers, and interference rejection techniques are the identified long term research areas.

Abstract In this paper, linearity and efficiency degrading mechanisms within envelope elimination and restoration transmitters are explained and demonstrated through simulations. A modified transmitter architecture is proposed to overcome these shortcomings. The proposed and conventional envelope elimination and restoration transmitter performances are compared and it is demonstrated that the proposed architecture provides better linearity and efficiency.

Modern digital modulation formats are generally phase-sensitive. Therefore, the variable attenuators in digital wireless equipment should exhibit minimal phase variation over attenuation. The hybrid coupled attenuator (HCA) has substantially less phase variation than the competing constant-impedance attenuators such as the Pi and the Bridged-T. At microwave frequencies, HCA implementations tend to suffer from reduced dynamic (attenuation) range due to component parasitics, especially when plastic-packaged PIN diodes are selected to lower cost. To maximize the dynamic range in a low-cost 1.9 GHz HCA , we first identified the critical components and then compensated for their deleterious effect. This paper describes the component and circuit changes that we made and their contribution to the dynamic range improvement.
The parasitics of the SOD-323 packaged PIN diodes can be null out using a modication of the Waugh technique that halves the number of compensatory components that he used. Minimizing the parasitics in the load resistors and bias inductors can further improve the HCA dynamic range. In conclusion, compensating for the parasitics in the PIN diodes, load resistors and bias inductors can significantly improve the HCA's dynamic range. Furthermore, the improvement can be had without increasing the part count.
Keywords - variable attenuator, voltage variable attenuator, hybrid coupled attenuator, dynamic range improvement, 1.9 GHz

This paper introduces a modified enhanced transmission-line theory to account for higher-order modes while using a standard transmission line equation solver or equivalently a Baum, Liu and Tesche (BLT) equation solver. The complex per-unit-length parameters as defined by Nitsch et al. are first cast into an appropriate per-unit-length resistance, inductance, capacitance and conductance (RLCG) form. Besides, these per-unit-length parameters are modified to account for radiation losses with reasonable approximations. This modification is introduced by an additional per-unit-length resistance. The reason and explanations for this parameter are provided. Results obtained with this new formalism are comparable to those obtained using an electromagnetic full-wave solver, thus extending the capability of conventional transmission line solvers.

An amplifier where the third order IM distortion has been reduced is proposed. If two signals at different carrier frequencies are incident at the input of an amplifier, due to the nonlinearity, these signals will interact with each other and the output will contain additional signals at all combinations of sum and difference of these frequencies, which are IM products. The injection of the second harmonics of the two input in the amplifier together with the fundamental signals will produce additional IM products at the output. By proper selection of phase and amplitude of the injected second harmonics, it is possible to make the third order IM products produced by the second harmonics and the original third order IM products out of phase and equal in amplitude. As a result third order IM products will be eliminated, in principle. Theory and simulation results obtained at 2.5 GHz are presented which supports the suggestion

Descreve-se neste trabalho as observações da atenuação suplementar devida a chuva feitas durante dois anos num feixe trabalhando em 11,5 GHz e com 5,4 Km, situado na região de Lisboa. Observou-se a frequência com que certas atenuações eram ultrapassadas, as durações dos acontecimentos individuais e os espaços de tempo decorridos entre acontecimentos individuais. Apesar do número de acontecimentos não ser grande, verificaram-se certas regularidades que sugerem que estas grandezas seguem certas distribuições. Por último tentou-se comparar algumas das observações feitas no feixe (as que dizem respeito à frequência coa que os níveis de atenuação são ultrapassados) coa curvas idênticas, construídas a partir de observações pluviométricas obtidas numa estação meteorológica situada próxima do feixe; os resultados desta comparação parecem ser animadores.

Module E20. This module is an accurate 3D electrostatic MoM solution for a self-capacitance of basic conducting objects. The conducting object may be a plate or a circle, a conducting brick, a sphere, or a cylinder. The module also computes charge distributions on conductors, electric field/electric potential distribution in a plane, and electric field/electric potential at a point of interest.
Surface Charge Density
Easy: Circular vs. Square Plate: Show the difference in the charge distribution & self-capacitance: Plot the change in Electrical field (Ez component) at the observation point as a function of height (z) above the circular and square plates:
Medium: Sphere: Show theoretical calculation of surface charge density on a sphere. Why is the surface charge distribution uneven in the simulation? Cylinder: Show self-capacitance E-z at (0,0,0.05) as a function of the radius/length ratio.
Difficult: Box: Why is the charge distribution strongest at the corners of the box? Can you calculate the closed-form of the charge distribution at the corners of the box?
Module E21: This module accurately computes the capacitance of a parallel-plate capacitor. It also computes charge distributions on capacitor plates, electric field/electric potential distribution in a plane, and electric field/electric potential at a point of interest (marked by a cross). Arbitrary (non-equal) plane sizes and/or orientations may be tested.
Capacitance between two plates
Compare the capacitance for the two-plate problem with the default potentials and parameters
Easy: What is the capacitance as a function of the Plate Area/separation for the simulation? (Compare at least 10 values) Compare this to the analytical solutions.
Medium: If one of the plates has different dimensions than the other plate, how does the capacitance change as a function of the ratio of the surface area of the plates for a given
distance?
Difficult: Why is the capacitance different for the simulation vs. theory? Use figures and equations to explain. Is there a closed-form solution for two plates of unequal size?

A Wide band printed monopole antenna has been proposed for the ku-band applications in this paper. Proposed antenna radiates in the frequency range of 13.68GHz to 15.05GHz which are useful in Radiolocation and satellite mobiles. To design the antenna a low cost glass epoxy FR4 substrate has been utilised. The basic radiating element is a circular patch in which two slots were etched of which one is a square ring slot and the other is s circular slot. The overall dimension of the antenna is 40mm×48mm×1.59mm. Microstrip line feed is used to feed the slotted circular patch. A considerable gain of 2.8dB and 5.6dB is observed at the two intermediate resonating frequencies of 13.94GHz and 14.55GHz. The antenna structure consists of a circular patch with a square ring slot and a circular slot which is used to achieve proper impedance matching.

—A novel uniform theory of diffraction (UTD)-type diffrac-tion coefficient for a straight edge in a cylindrically curved screen valid for both convex and concave side wave incidence is obtained via uniform asymptotic theory of diffraction (UAT) formulations. The proposed curved screen UTD-type coefficient (CSUTD) allows uniform description of the fields at all aspect angles including the grazing incidence case, where UTD coefficient-based predictions deviate sharply from available measurements , when it is applied to the problem of monostatic radar cross section (RCS) of cylindrically curved plate. Index Terms—Asymptotic diffraction theory, curved plate radar cross section (RCS), straight edge in a curved screen, uniform asymptotic theory of diffraction (UAT), uniform theory of diffraction (UTD).

At the frequencies above 10 GHz rain may be the cause of severe fading and so must be taken into account in the design of radio links. To this end it is natural that use is made of meteorological data gathered near the path of the future link. However it is difficult to define exactly what data should be taken from which to deduce the statistical proneiti.es of the fading to be exnected in the link; the dificulties arise mainiy (i) fTom the variability from one year to the next of the précipitation at a given place, and (ii) from the non uniform distribution of the rain in space, on a smaller scale than the length of most links. So, to gain knowledge on these problems, and in addition to theoretical approaches, there is a need for observations to be carried on existing links and then be compared with prédictions derived from observations at nearby meteorological stations- Such a set of observations is described and the results are compared with prédictions based in différent treatments of the meteorological data.