Analysis of L-probe Proximity Fed Annular Ring Patch Antenna for Wireless Applications

In the present paper, annular ring patch antenna with L-probe feeding has been analyzed using modal expansion cavity model. The proposed antenna shows wide band and ultra wide band operation which depends on the position of L-probe feeding and position of the shorting pin. For the fundamental \(\hbox {TM}_{11}\) mode, the bandwidth and gain is found to be 38.85 % and 7.8 dBi while for higher order \(\hbox {TM}_{12}\) mode bandwidth is obtained 58.71 % with corresponding gain of 6.1 dBi. The effect of shorting pin on the proposed antenna is also studied and it is found that the radiating structure is more compact in nature and improves the bandwidth upto 47.37 % with 8.0 dBi gain. Further, the proposed antenna has broadside radiation pattern over the entire bandwidth. The theoretical results are compared with IE3D simulated results which are in good agreement.     

Compact Planar Monopole Antenna with Dual Band Notched Characteristics Using T-Shaped Stub and Rectangular Mushroom Type Electromagnetic Band Gap Structure for UWB and Bluetooth Applications

In this paper, an ultra-wideband (UWB) antenna with dual band-notched characteristics is proposed. The proposed antenna also covers ISM (Industrial, Scientific, and Medical)/Bluetooth band. The antenna consists of a microstrip fed truncated U-shaped patch, T-shaped stub, rectangular mushroom type electromagnetic band gap structures (EBG), and partial ground plane. To mitigate the problem of interference due to standard narrow bands (like wireless interoperability microwave access (WiMAX) and wireless local area network (WLAN)) lie in the range of UWB, dual band notched characteristics is introduced. The WiMAX and WLAN band notched characteristics are realized by introducing a T-shaped stub and rectangular mushroom type EBG structures, respectively. The proposed antenna is printed on a 1.6 mm thick FR4 substrate with relative permittivity \((\upvarepsilon _{\mathrm{r}})\) 4.4 and the size of actual antenna is \(36 \times 40\hbox { mm}^{2}\) . The measured results shows that the proposed antenna attains a wide impedance bandwidth \((\hbox {VSWR} \le 2)\) from 2.35 to 11.6 GHz with dual band notched characteristics from 3.29 to 3.9 GHz and 5.1 to 5.85 GHz with stable radiation patterns. The time domain behaviors of the proposed antenna is also analyzed for pulse handling capability.     

A Novel Design of Low Power Rectenna for Wireless Sensor and RFID Applications

In this paper, an efficient microstrip rectenna operating on ISM band with high harmonic rejection is presented. By using rotated E-shaped strip in the radiating patch, a new resonance at lower frequencies (2.4 GHz) can be achieved. Also by embedding cutting a rectangular slot with protruded interdigital strip inside the slot in the feed line a frequency band-stop performance can be achieved. The proposed structure has a major advantage in high harmonic rejection. The rectenna with integrated monopole antenna can eliminate the need for an low pass filter placed between the antenna and the diode as well as produce higher output power, with maximum conversion efficiency of 74 % using a 1 K \(\Omega \) load resistor at a power density of \(0.3\,\hbox {mW/cm}^{2}\) .     

Six Order Cascaded Power Line Notch Filter for ECG Detection Systems with Noise Shaping

This paper presents the design of an operational transconductance amplifier-C (OTA-C) notch filter for a portable Electrocardiogram (ECG) detection system. A six order cascaded filter is utilized to reduce the effect of the power line interference at (50/60 Hz). The proposed filter is based on a programmable balanced OTA circuit. Based on this, PSPICE post layout simulation results for the extracted filter using 0.25  \(\upmu \) m technology and operating under \(\pm \) 0.8 V voltage supply are also given. The six order notch filter provides a notch depth of 65 dB (43 dB for 4th order), input referred noise spectral density with noise shaping of 9  \(\upmu \) Vrms/ \(\surd \) Hz at the pass band frequencies and 9 mVrms/ \(\surd \) Hz at the notch (zero) frequency which provide noise shaping for the ECG signal. These results demonstrate the ability of the filter to be used for ECG signal filtering which is located within 150 Hz.     

Design and Simulation of a Novel Micromachined Frequency Reconfigurable Microstrip Patch Antenna

In this paper, a novel model of a frequency reconfigurable microstrip patch antenna based on MEMS (microelectromechanical system) technology is introduced. Fabrication process of the proposed antenna is comprised of bulk and surface micromachining. Patch of the antenna is deposited over a silicon platform. The platform is created by structuring the silicon membrane which is formed through bulk micromachining of a silicon chip. The patch and the platform beneath it are discretized to facilitate their vertical displacement over underside air gap. Thermal actuation is used as driving mechanism. Operational mechanism of the antenna is such that by downward relocation of the patch, its resonant frequency shifts downward. Thermal actuators are connected to the platform and applying voltage to them cause downward shift in resonant frequency of the antenna. FEM (finite element method) simulations confirm mechanical and microwave performances of the antenna which are investigated by theoretical analyses. From mechanical point of view, antenna has tolerable mechanical stability and microwave point of view indicates that return losses are good (below $-$ 10 dB) and radiation patterns are very close to each other with reasonable gains. Moreover VSWR is less than 2 throughout the frequency tuning range. In the proposed antenna by applying a CMOS compatible voltage in the range of 0–4.5 V to each thermal actuator, the resonant frequency of the antenna shifts from 17.37 GHz in up-sate position to 15.07 GHz in down-state position. As a result of this frequency shift, a frequency tuning range of 2.3 GHz with bandwidths of 3.9 % in up-state and 1.4 % in down-state positions is achieved.     

Design of an Ultra-Wideband Microstrip Patch Antenna Suspended by Shorting Pins

Designing a compact wideband microstrip patch antenna which is composed of a folded-patch feed, a symmetric E-shaped edge and shorting pins is presented in this paper. One pin is applied in order to expand the impedance bandwidth. Two other pins are utilized to miniaturize the size of patch as well. The measured impedance bandwidth ( $\text{ VSWR}\le 2$ ) of the fabricated antenna is more than 90 % in the frequency range 3.92–10.67 GHz for ultra-wideband (UWB) applications. The antenna size is $0.438\lambda _{0}\times 0.365\lambda _{0}\times 0.170\lambda _{0}$ at its center operating frequency. Also, radiation patterns with acceptable stability within the bandwidth are obtained. In addition, the effects of some key parameters are investigated to describe the performance of the proposed design.     

A Statistical Model for the Influence of Body Dynamics on the Gain Pattern of Wearable Antennas in Off-Body Radio Channels

The goal of this paper is to address a statistical approach for modelling the influence of body dynamics on the gain pattern of wearable antennas in Body Area Networks, particularly in off-body radio channels. A dynamic model was developed based on Motion Capture data, describing a realistic human body movement. Antennas are located on 4 typical positions (i.e., Head, Chest, Arm and Leg), for which statistics of antenna orientation (i.e., average and standard deviation of elevation and azimuth angles) were calculated for 2 dynamic scenarios, i.e., Walk and Run. Based on the rotation of the antenna, the statistics of gain patterns of a wearable patch antenna operating at 2.45 GHz were calculated. The standard deviation of the change in the antenna orientation is the highest for the Arm location, reaching $19^{\circ }$ and $37^{\circ }$ for the Run scenario, for elevation and azimuth angles, respectively. For most of the scenarios, the distribution of the change in antenna orientation fits well to a Kumaraswamy distribution (using the $\chi ^2_{95\,\%}$ test). For all antenna positions and the Walk scenario, the standard deviation is $<4^{\circ }$ .     

Compact Coplanar Waveguide-fed Planar Antenna for Ultra-wideband and WLAN Applications

A novel compact planar antenna is presented for Ultra-wideband (UWB) applications in this paper. The proposed antenna has rectangle-like slot and it is fed by coplanar waveguide. The antenna is printed on FR4 substrate and it has compact size of $28 \times 31 \times 0.8 \,\,\text{ mm}^{3}$ . Parametric study is performed on the antenna by investigating the effect of various geometrical parameters on the frequency characteristics. The antenna is fabricated and measured. It has better return loss response and stable gain over the entire UWB band. The antenna has stable radiation pattern and good impedance matching over entire ultra-wide bandwidth of 3–10.6 GHz. The results show that there is good agreement between measured and simulated results. Various features such as compactness, simple configuration and low fabrication cost make the antenna suitable for UWB and wireless local area network systems.     

Miniaturized Trapezoidal Patch Antenna with Folded Ramp-Shaped Feed for Ultra-Wideband Applications

A novel design for compact probe-fed wideband microstrip patch antenna for ultra-wideband (UWB) applications is proposed in this paper. The antenna consists of a folded ramp-shaped feed, trapezoidal patch and shorting pins. By adding two pins at end side of the patch, its size is miniaturized. The measured impedance bandwidth (VSWR  $\le $  2) of fabricated antenna is more than 130 % from 3.7 to 17.6 GHz. This antenna achieves an acceptable miniaturization and provides an excellent UWB impedance bandwidth with stable radiation patterns. It is shown by simulated results how the bandwidth can be considerably increased by introducing novel feeding method namely, the folded ramp-shaped feed. Likewise, the parametric study is performed to describe the characteristics of the proposed antenna. Moreover, good antenna performances such as radiation patterns, acceptable miniaturization and antenna gains over the operating band have been observed.     

A Wide Tuning Range Voltage Controlled Oscillator with a High Tunable Active Inductor

This paper presents a wide tuning range CMOS voltage controlled oscillator (VCO) with a high-tunable active inductor circuit. In this VCO circuit, the coarse frequency is achieved by tuning the integrated active inductor circuit. The VCO circuit is designed in 0.18  \(\upmu \hbox {m}\) CMOS process and simulated with Cadence Spectra. The simulation results show the frequency tuning range from 120 MHz to 2 GHz resulting in a tuning range of 94 %. The phase noise variation is from \(-\) 80 to \(-\) 90 dBc/Hz at a 1 MHz frequency offset, and output power variation is from \(-\) 4.7 to \(+\) 11.5 dBm. The active inductor power consumption is 2.2 mW and the total power dissipation is 7 mW from a 1.8 V DC power supply. By comparing the proposed VCO circuit with the general VCO topology, the results show that this VCO architecture by using the novel, high-tunable and low power active inductor circuit, presents a better performance regarding low chip size, low power consumption, high tuning range and high output power.     

Dual-Band Antenna Fed with CPW Technology Using Modified Mirrored L-Shaped Conductor-Back Plane

This paper describes a novel configuration of a CPW-fed printed monopole antenna that depicts dual-band operations of WLAN and X-bands. The proposed antenna consists of a simple rectangular-shaped patch as the main radiator, the modified mirrored L-shaped conductor back plane element, and the partial rectangular CPW-ground surface. Dual-band performances can be obtained by embedding and adjusting dimensions of strips on mirrored L-Shaped conductor back plane element. The impedance bandwidth with \(\hbox {s}_{11} < -10\)  dB is about 2.2 GHz (5.05–7.25 GHz) or 36 % for 5 GHz band and 5.2 GHz (7.6–12.8 GHz) or 51 % for X-band. The measured peak gains are about 1.8 dBi at WLAN-band and 4.3 dBi at X-band. The Experimental results indicate that the fabricated antenna with proper dimensions, good radiation characteristics, and reasonable measured gains can be a good candidate for various applications of the future multi-band wireless communication systems and mobile device.     

A Novel 2.5–3.1 GHz Wide-Band Low-Noise Amplifier in 0.18 \upmu \hbox {m} CMOS

Aiming for the simultaneous realization of constant gain, accurate input and output impedance matching and minimum noise figure (NF) over a wide frequency range, the circuit topology and detailed design of wide broadband low noise amplifier (LNA) are presented in this paper. A novel 2.5–3.1 GHz wide-band LNA with unique characteristics has been presented. Its design and layout are done by TSMC 0.18  \(\upmu \hbox {m}\) technology. Common gate stage has been used to improve input matching. In order to enhance output matching and reduce the noise as well, a buffer stage is utilized. Mid-stages which tend to improve the gain and reverse isolation are exploited. The proposed LNA achieves a power gain of 15.9 dB, a NF of 3.5 dB with an input return loss less than \(-\) 11.6, output return loss of \(-\) 19.2 to \(-\) 19 and reverse isolation of \(-\) 38 dB. The LNA consumes 54.6 mW under a supply voltage of 2 V while having some acceptable characteristics.     

Electronically scanned RF-to-bits beam aperture arrays using 2-D IIR spatially bandpass digital filters

A beamforming system based on two-dimensional (2-D) spatially bandpass infinite impulse response (IIR) plane wave filtering is presented in a multi-dimensional signal processing perspective and the implementation details are discussed. Real-time implementation of such beamforming systems requires modeling of computational electromagnetics for the antennas, radio frequency (RF) analog design aspects for low-noise amplifiers (LNAs), mixed-signal aspects for signal quantization and sampling and finally, digital architectures for the spatially bandpass plane wave filters proposed in Joshi et al. (IEEE Trans Very Large Scale Integr Syst 20(12):2241–2254, 2012). Multi-dimensional spatio-temporal spectral properties of down-converted RF plane wave signals are reviewed and derivation of the spatially bandpass filter transfer function is presented. An example of a wideband antipodal Vivaldi antenna is simulated at 1 GHz. Potential RF receiver chains are identified including a design of a tunable combline microstrip bandpass filter with tuning range 0.8–1.1 GHz. The 1st-order sensitivity analysis of the beam filter 2-D $\mathbf z $ -domain transfer function shows that for a 12-bits of fixed-point precision, the maximum percentage error in the 2-D magnitude frequency response due to quantization is as low as $0.3\,\%$ . Monte-Carlo simulations are used to study the effect of quantization on the bit error rate (BER) performance of the beamforming system. 5-bit analog to digital converter (ADC) precision with 8-bit internal arithmetic precision provides a gain of approximately 16 dB for a BER of $10^{-3}$ with respect to the no beamforming case. ASIC Synthesis results of the beam filter in 45 nm CMOS verifies a real time operating frequency of 429 MHz.     

Algebraic integer architecture with minimum adder count for the 2-D Daubechies 4-tap filters banks

A multiplierless architecture based on algebraic integer representation for computing the Daubechies 4-tap wavelet transform for 1-D/2-D signal processing is proposed. This architecture improves on previous designs in a sense that it minimizes the number of parallel 2-input adder circuits. The algorithm was achieved using numerical optimization based o exhaustive search over the algebraic integer representation. The proposed architecture furnishes exact computation up to the final reconstruction step, which is the operation that maps the exactly computed filtered results from algebraic integer representation to fixed-point. Compared to Madishetty et al. (IEEE Trans Circuits Syst I (Accepted, In Press), 2012a), this architecture shows a reduction of \(10\cdot n-3\) adder circuits, where \(n\) is the number of wavelet decomposition levels. Standard \(512\times 512\) images Mandrill, Lena, and Cameraman were submitted to digital realizations of both proposed algebraic integer based as well as fixed-point schemes, leading to quantifiable comparisons. The design is physically implemented for a 4-level 2-D decomposition using a Xilinx Virtex-6 vcx240t-1ff1156 FPGA device operating at up to a maximum clock frequency of 263.15 MHz. The FPGA implementation is tested using hardware co-simulation using an ML605 board with clock of 100 MHz. A 45 nm CMOS synthesis shows improved clock frequency of better than 500 MHz for a supply voltage of 1.1 V.     

A 3–10 GHz Ultra Wideband Receiver LNA in 0.13 \mu m CMOS

A fully integrated low-power, low-complexity ultra wideband (UWB) 3–10 GHz receiver front-end in standard 130 nm CMOS technology is proposed for UWB radar sensing applications. The receiver front-end consists of a full UWB band low-noise amplifier and an on-chip diplexer. The on-chip diplexer has a 1 dB insertion loss and provides a \(-\) 30 dB isolation. The diplexer switch was co-designed with the receiver input matching network to optimize the power matching while simultaneously achieving good noise matching performance. The receiver low-noise amplifier provides a 3–10 GHz bandwidth input matching and a power gain of 17 dB. The overall receiver front-end consumes an average power of 13 mW. The core area of the transceiver circuit is 500 \(\mu \) m by 700 \(\mu \) m.     

Will New Antenna Materials Enable Single Path Multiple Access (SPMA)?

The aim of this paper is to introduce a novel frequency reuse concept especially for macro cellular networks to substantially increase the mobile network capacity, and simultaneously to avoid the implementation of low efficient small cells. Single path multiple access (SPMA) utilizes the characteristics of independent propagation paths for particular geographical location in the coverage area of mobile network. The proposed concept is based on the assumption that new approach will be adopted by the antenna manufacturers for producing advanced antennas by utilizing materials like metamaterials including carbon based nanotechnology, and graphene. In SPMA concept, communication between base station and mobile station happens through only single independent propagation path, and frequency resources can be reused in 5 m  \(\times \)  5 m areas or even more often in 1 m  \(\times \)  1 m areas, but limited by a base station/mobile station antenna requirement. Thus, the capacity of the network will be increased dramatically, and it can be managed in centralized manner at certain macro site locations. In already deployed cellular networks, these macro sites are mostly easily available, and that would help to implement SPMA to enhance the network capacity. Simulation results provided in this paper show the applicability of SPMA technique, by limiting the radiation of signal as single path propagation between base station and mobile station.     

The First Year Nursing Students’ Achievement and Critical Thinking in Local Wisdom Course Using Problem Based Learning Process

The purpose of this one group—pre test post test design classroom research was to examine learning achievement, critical thinking and satisfaction of first year nurse students at school of nursing during academic year 2011. In the research activity, 94 students participated in three weeks for each scenario in Local Wisdom and Health Care which composed of 4 scenarios. Problem based learning process were included the preparation of facilitators, preparation of learners, and problem/scenario based assignments. The instruments composed of 1) 135 items, 4 multiple choices test which were covered behavioral objectives and blue print of test and validated by course lecturers 2) opinion evaluation form, open ended questionnaire and 3) the critical thinking questionnaire, 80 items in five domains which are Inference, Recognition of Assumption, Deduction, Interpretation, and Evaluation of Argument with internal consistency of .73. Data were analyzed using frequency, percentage, mean, standard deviation, percentile, t test and $\chi ^{2}$ test. It was found that the highest score of learning achievement was 88.79 % while the lowest score was 70.33 %, average learning achievement score was 80.60 $(\pm 3.47)\%$ . The highest grade levels were B+ and B equally (41.49 %). Students demonstrated higher overall critical thinking $(49.62 \pm 5.78)$ after undergone problem based learning process than before the problem based learning process $(46.69 \pm 6.00)$ statistically significance $(\text{ t}\,=\,4.443, p\,<\,.05)$ . Inference and Recognition of Assumption domain after PBL process were better than their own thoughts before PBL process significantly (t = 2.288, $p\,<\,.05$ ; t = 6.287, $p\,<\,.05$ , respectively). The ability of critical thinking was found that the high, moderate and low level (percentile $>75, 25-75$ and $<25$ ) after PBL were difference from the ability before the process significantly $(\chi ^{2}=12.219, p\,<\,.05)$ .     

A High Gain and Low Flicker Noise CMOS Mixer with Low Flicker Noise Corner Frequency Using Tunable Differential Active Inductor

This paper presents the design of a high conversion gain and low flicker noise down conversion CMOS double balanced Gilbert cell mixer using \(0.18\,\upmu \hbox {m}\) CMOS technology. The high conversion gain and low flicker noise mixer is implemented by using a differential active inductor (DAI) circuit and cross-coupled current injection technique within the conventional double-balanced Gilbert cell mixer. A cross-coupled current bleeding circuit is used to inject the current to the switching stage to decrease the flicker noise. Instead of spiral inductor, a DAI with high tunability of the inductor and quality factor is used to tune out the parasitic capacitance effect and decrease the leakage current that has a harmonic component and produce the flicker noise. By tuning the DAI, the flicker noise corner frequency is reduced to 150 Hz. The proposed circuit is simulated with Cadence Spectra and the simulation results shows the NF of 11.2 dB, conversion gain of 23.7 dB and IIP3 of \(-6\)  dB for an RF frequency of 2.4 GHz. The excellent LO-RF, LO-IF, RF-LO and RF-IF isolations of \(-60, -110, -52\) and \(-64\)  dB are achieved respectively. The total power consumption is 10.5 mW from a 1.8 V DC power supply.     

Performance Analysis of a Low Profile Hybrid Antenna for Broadband Applications

In this paper, a low profile dielectric resonator antenna (DRA) is proposed and investigated. To achieve the broad impedance bandwidth the proposed antenna geometry combines the dielectric resonator antenna and an underlying microstrip-fed slot with a narrow rectangular notch, which effectively broadens the impedance bandwidth by merging the resonances of slot and DRA. The physical insight gained by the detailed parametric study has led to find out a set of guidelines for designing the antennas for any particular frequency band. The design guidelines have been verified by simulating a set of antennas designed for different frequency bands. For validation, a prototype antenna is fabricated and tested experimentally. The measured results show that the proposed DRA offers an impedance bandwidth of about \(125.34\%\) from 1.17 to 5.1 GHz with reasonable gain between 3.5 and 5.7 dBi. The volume of the proposed DRA is \(0.16\lambda _{dr}^{3}\), where \(\lambda _{dr}\) is the wavelength at center operating frequency of the DR. A comprehensive study on bandwidth shows that the proposed DRA provides maximum bandwidth in terms of the DR volume (\(\hbox {BW}/V_{dr}\)) and the DR height (\(\hbox {BW}/h_{dr}\)) than the other similar reported work on hybrid wideband DRA designs.     

Improved Q-Factor Calculations for Single Port Filter-Antenna Measurement

These days most of the research work in the area of filter-antenna design is focused on having high quality factor for certain frequency band. These type of filter-antennas are difficult to design as the design engineers are required to have low quality factor for the radiating band of frequency. Hence a precise value of $Q$ -factor is required to understand the radiating and filtering properties of filter-antennas. Filter-antennas are single port devices as the second port is considered as radiating port. Return loss is used, in order to yield $Q$ -factor through calculations for such devices. However, the conventional method for calculating $Q$ -factor found to be inaccurate in most of the low $Q$ -factor cases. This paper proposes a method that out performs the conventional method of calculating $Q$ -factor. Non-ideal fabrication process is also discussed for accurate evaluation of $Q$ -factor. Experimental results show that proposed method can be employed to calculate $Q$ -factor with reasonable accuracy for simulated and measured results.