A 0.18 µm CMOS Binary Frequency Shift Keying Modulator with a novel frequency synthesizer structure is proposed in this paper. Based on an analog adder technique being the backbone of the synthesizer, this prototype demonstrates a compact modulator with low complexity, which achieves 1 Mbps at 400 MHz while dissipating 3.1 mW at 1.5 V supply. The proposed design is ideal for biomedical sensor network systems including distributed wearable body area network.

In this paper, an amplitude shift keying (ASK) demodulator with 100% modulation depth is proposed. In order to achieve the higher power and wider reading range the designed ASK demodulator works in the ultra-high frequency. In this design, the average detector and voltage divider are used in order to define the appropriate threshold voltage level for the radio frequency input signal which leads to the accurate data detecting even at long distances between the tag and reader. In addition, for diminishing the power dissipation of the proposed demodulator, an enable input is used in the buffer and comparator. This circuit is simulated in 0.18 μm complementary metal–oxide–semiconductor (CMOS) technology with Cadence software. Its power dissipation and chip area are 3.9 nW and 0.0025 mm2, respectively.

A 10 × 10 μm2 SiGe heterojunction bipolar photo-transistor (HPT) is fabricated using a commercial technological process of 80 GHz SiGe bipolar transistors (HBT). Its technology and structure are first briefly described. Its optimal opto-microwave dynamic performance is then analyzed versus voltage biasing conditions for opto-microwave continuous wave measurements. The optimal biasing points are then chosen in order to maximize the optical transition frequency (fTopt) and the opto-microwave responsivity of the HPT. An opto-microwave scanning near-field optical microscopy (OM-SNOM) is performed using these optimum bias conditions to localize the region of the SiGe HPT with highest frequency response. The OM-SNOM results are key to extract the optical coupling of the probe to the HPT (of 32.3%) and thus the absolute responsivity of the HPT. The effect of the substrate is also observed as it limits the extraction of the intrinsic HPT performance. A maximum optical transition frequency of 4.12 GHz and an absolute low frequency opto-microwave responsivity of 0.805A/W are extracted at 850 nm.

Null steering has been a challenge in radar communications for the past few decades. In this paper, a novel cognitive null steering technique in frequency diverse array radars using frequency offset selection is presented. The proposed system is a complete implementable framework that provides precise and deep null placement in the range and angle locations of the interference source. The proposed system is cognitive such that the transmitter and receiver are connected via a feedback loop. System extracts interference source location parameters from the radar scene using Multiple Signal Classification, a super resolution direction of arrival estimation technique. Neural networks known for minimum computation time, and good non-linear and non-parametric approximation have been utilized for prediction of next location of the interference source. Simulation results validate the proposed frequency offset selection by demonstrating precise and deep nulls at the desired locations.

As a recently proposed concept, multiple-input multiple-output (MIMO) radars exhibit much higher spatial resolution than traditional transmitter based radars because of the synthesized virtual array. In this paper, the problem of minimum redundancy (MR)-MIMO array synthesis is addressed, which seeks to maximize the virtual array aperture of MIMO radars for a given number of transmitting and receiving elements. A hybrid method combining autocorrelation property of cyclic difference sets (CDSs) and global search characteristics of ant colony optimization (ACO) is proposed for a rapid and numerically-effective exploration of MR-MIMO array configurations. Numerical experiments validate the proposed method, showing improvements in convergence rate and computational cost with respect to bare ACO-based search as well as improvements in the generality and configuration variety with respect to the CDS-based method.

This paper presents, a dual-band bandpass filter using asymmetric stepped impedance stub loaded open loop resonator (OLR) for WLAN and WiMAX application. The outer OLR is realized to operate at lower passband of 2.45 GHz which is directly coupled to input and output ports whereas the asymmetric stepped impedance stub that loads the outer resonator contributes to 3.5 GHz passband. The introduction of asymmetric stepped impedance stub provides further control of improving the upper passband edge selectivity of second passband and in shifting the spurious modes away from second band thereby contributing to the wide upper stopband. The insertion loss is within 1.5 dB for each passband with 10 dB passband bandwidth of 250 MHz at both bands. A stopband up to 10 GHz is also obtained. A prototype is developed and the s-parameters obtained from electromagnetic simulation, equivalent transmission line model and measurement are in close agreement. The overall dimension of the filter is 25.45 × 15.89 mm2 which renders it a compact size.

In this manuscript, serial-shunt of square ring resonators with step-impedance open circuited stub resonators to produce a new on-off switchable bandpass to bandstop response in the same ultra-wideband microstrip filter structure is proposed. The closed ring of series-shunt square ring resonators with a combine stubs are introduced to excite the bandpass response while bandstop characteristic excited when gaps are embedded in the corners of the square ring resonators. The main advantage of this microstrip filter is its capability to switch from bandpass-to-bandstop operation using open-short gap, respectively. A microwave simulator is utilized to show the switchable case by replacing Skyworks radio frequency diodes (RF-PIN) instead of those gaps. The entire filter models have been simulated using the computer simulation technology (CST) Microwave Studio. The computed results for the proposed filters were compared with the measured results of the both prototype structures (bandpass- and bandstop-filter). The codes also showed good agreement between them. Other advantages include being small in size, and low in effective cost.

In this paper, a new kind of admittance inverter and design of a switchable microstrip bandpass filter using composite right/left-handed (CRLH) cells has been presented. The proposed filter has two states (or passbands). One of the two passbands, is accessible at each time by on/off state of three PIN diodes. This filter is a three-pole, coupled resonator filter, composed of short-circuited shunt resonators. These resonators are coupled using admittance inverters. With regard to the characteristics of the equivalent circuit of CRLH cells, a new structure of admittance inverter (J-inverter) has been introduced. This novel J-inverter has PI-section equivalent circuit and it consists of both inductive and capacitive elements. In our work, the proposed J-inverter was mathematically studied and the switchable filter was simulated and implemented. The results of simulations for the first and second state of the filter, which are frequency bands of (Δ1 = 0.11 and f1 = 1.26 GHz) and (Δ2 = 0.12 and f2 = 1.5 GHz), are verified by measurements.

A novel planar printed phase shifter design is proposed in this paper. The design is developed with microstrip–conductor-backed coplanar waveguide– microstrip (MP–CBCPW–MP) transition line with different defected ground structures (DGS). The differential phase shift can be controlled by altering the DGS dimensions. Three prototypes with DGS dimensions 5 × 10, 10 × 20, and 10 × 30 mm2, are employed at the finite ground plane to achieve 5°, 20°, and 30° shift in phase respectively and are validated with the phase delay relation. The prominent effect of the transition region is to confine the field area. The resonance is at 700 MHz with a bandwidth of 400 MHz (0.4–0.8 GHz). The proposed phase shifter can be used for broadcasting applications. The proposed MP–CBCPW–MP transition phase shifter design with DGS is simulated, fabricated, and measured to analyze its performance.

The growing demand for communication systems requires multi-channel solutions. However, the number of antennas in communication systems is dictated by the number of channels in each system which is limited by the available space on a broadcasting platform and by the limited available resources. We have developed a Multi-Channel Phase Control coupler in the VHF frequency range enabling a reduction in the number of antennas to a third of the original setup. The system is based on a phase shifter in a meander stripline geometry connected to each channel individually. The channels are then phase matched simultaneously to a single antenna through a computer-controlled capacitor bank connected to each phase shifter. The system performance shows a low insertion loss of 0.5 dB and a low return loss of −15 dB for the multi-channel setup.

This paper proposes an efficient and fast analysis of substrate integrated waveguide (SIW) components using a new approach of the iterative method called WCIP, i.e. “Wave Concept Iterative Process”. This method is based on the iterative resolution of waves between two domains. The first is the spectral domain. We use the Floquet–Bloch decomposition to describe all modes in the spectral domain. The second describes the configuration of the circuit in the spatial domain. It allows taking the exact structure according to the appropriate boundary conditions. This method permits to reduce numerical complexity. The convergence of this approach is always guaranteed. The theoretical suggested study is validated by the simulation of two different examples of SIW circuits. The obtained results are in good agreement with those of measurement and with software HFSS simulations, which prove the advantage of this method.

An ultra-wideband (UWB) frequency-selective surface (FSS) exhibiting band rejection characteristic is presented in this paper. The proposed unit cell has the size of 14 × 14 mm2 which is approximately 0.18 × 0.18 λo, where λo corresponds to free space wavelength at the lower cut-off frequency. The proposed UWB FSS consists of a single-layer substrate and provides 20 dB attenuation level for a wide bandwidth of 7.53 GHz at the normal incidence. The proposed FSS is polarization independent and also provides angular-independent operation for the EM wave incidences of 15°, 30° and 45° with 11.5 dB attenuation over a wide range from 4 to 14 GHz.

A novel multiport system, allowing for measurements of scattering parameters in over-two-octave frequency range is proposed. It is composed of two directional couplers and a standard 4 × 4 Butler matrix, and does not require any isolators. The presented system features a uniform power distribution providing the high precision of measurements, which can be further enhanced by a simple adjustment of the system's parameters. A comprehensive analysis of the proposed system configurations, a fully analytical calibration for transmission coefficient measurement, and the estimation of maximum measurement error are given. The proposed measuring system has been experimentally verified in a wide frequency range 1–5 GHz, by measurements of S-parameters of exemplary components. The measurement results are very close to the values obtained with the use of a commercial vector network analyser within the 50 dB range of measured values’ magnitude.

A wideband four element triangular dielectric resonator antenna (TDRA) has been designed and fabricated by using 50 Ω coaxial probe feed. The input and radiation characteristics of the proposed antenna have been extracted through Ansoft HFSS and CST Microwave Studio simulation software and compared with the experimental results. The simulated results have been in good agreement with the experimental results. The proposed antenna characteristics have also been compared with the same dimensions of the single element TDRA, and found enhancement in bandwidth with lower resonant frequency. Its performance has also been compared with same area (equal to proposed antenna) of single element TDRA. The proposed antenna provides nearly 37% bandwidth (|S11| < −10 dB) at a resonant frequency of 5.45 GHz with 4.76 dBi peak gain. The symmetry and uniformity in the radiation patterns is obtained consistently for the entire operating bandwidth. The proposed antenna shows consistently symmetric monopole type radiation pattern with low cross polarization for WLAN (IEEE 802.16) and WiMAX applications. The performance of the proposed antenna has been compared with some similar type of dielectric resonator antenna (DRA) shapes and it has been observed that TDRA is taking very less radiation area for giving better performance than other DRA shapes.

This paper presents different reconfigurable antennas with frequency, polarization, and pattern diversities. All the antennas have a very simple, novel, and compact structures, which are used for different wireless communication applications. These antennas employ switching for obtaining different reconfigurations. At first, an E-shaped antenna is designed for multi-band frequency reconfigurability. Second, circular and rectangular-shaped patch antennas are designed for achieving diversity in polarization. At last, a pattern reconfigurable antenna is designed with multiport excitation. These antenna performances are analyzed using various parameters such as return loss, radiation pattern, voltage standing wave ratio (VSWR), and gain. The prototypes of the antennas are fabricated and measured results along with simulated ones are presented. Both the results are in good agreement.

This paper presents the design, testing, and analysis of a clover structured monopole antenna for super wideband applications. The proposed antenna has a wide impedance bandwidth (−10 dB bandwidth) from 1.9 GHz to frequency over 30 GHz. The clover shaped antenna with a compact size of 50 mm × 45 mm is designed and fabricated on an FR4 substrate with a thickness of 1.6 mm. Parametric study has been performed by varying the parameters of the clover to obtain an optimum wide band characteristics. Furthermore, the prototype introduces a method of achieving super wide bandwidth by deploying fusion of elliptical patch geometries (clover shaped) with a semi elliptical ground plane, loaded with a V-cut at the ground. The proposed antenna has a 14 dB bandwidth from 5.9 to 13.1 GHz, which is suitable for ultra wideband (UWB) outdoor propagation. The prototype is experimentally validated for frequencies within and greater than UWB. Transfer function, impulse response, and group delay has been plotted in order to address the time domain characteristics of the proposed antenna with fidelity factor values. The possible applications cover wireless local area network, C-band, Ku-band, K-band operations, Worldwide Interoperability for Microwave Access, and Wireless USB.

In this paper, a band-notched compact printed monopole super wideband (SWB) antenna has been designed and fabricated. The SWB antenna composed of a radiating patch with a 50 Ω triangular tapered feed line which is connected through a feed region, and a chamfered ground plane (CGP), that covers the frequency band from 0.9–100 GHz (ratio bandwidth of 111.1:1) with a reflection coefficient |S11| < −10 dB, except in the notched band of 4.7–6 GHz for Wireless local area network IEEE 802.11a and HIPERLAN/2 WLAN band. To realize the band notch characteristics a C-shape parasitic element is employed near the CGP etched with two symmetrical L-slots and placed under the radiating patch. Proposed antenna structure occupies a relatively small space (30 × 40 × 0.787 mm3) and achieved much wider impedance bandwidth as well as higher gain compared with the existing ultra wideband and SWB antennas.

An ultra-wideband (UWB) slot antenna for diversity applications is introduced. The overall structure of the antenna consists of two similar coplanar waveguide (CPW)-fed stepped rectangular slots placed in an orthogonal position. The slots are asymmetric with respect to their placement in the ground plane. The CPW feeds are double stepped and terminated on hexagonal patches for better impedance matching. A wide impedance bandwidth (measured) from 3 to 12 GHz with an isolation better than 15 dB is obtained with this antenna. To improve the isolation, the design is modified and an I-shaped slot strip is introduced between the two slot antennas. With this, the isolation is brought about 25 dB of most of the band, while the impedance bandwidth remains the same (2.8–12 GHz for port 1, measured and 2.9–12 GHz for port 2, measured). The far-field radiation patterns are also measured and a peak gain of about 5 dBi is obtained. Finally, the diversity parameters such as envelope correlation coefficient and capacity loss are calculated and found to have low values. The antenna is expected to be useful for UWB diversity applications with good isolation.

In this paper, a compact, dual-band patch antenna is proposed over Minkowski fractal defected ground structure (DGS) for bandwidth enhancement of global positioning system (GPS) applications. The proposed design combines the truncated dual L-shaped slits cut on diagonal corners of radiating patch and fractal defect on the metallic ground plane. This concept shifts the frequencies to lower bands with improvement in antenna radiation properties. By deploying symmetrical and asymmetrical boundaries to the structure for the fractal DGS on metallic ground plane, improvement in bandwidth and gain are obtained. Compact antenna size is achieved for dual-band GPS frequencies of L1 (1.575 GHz) and L2 (1.227 GHz). The measured results for antenna prototype are (1.2–1.245 GHz): L2 band and (1.51–1.59 GHz): L1 band for 10 dB return loss bandwidth with better pattern radiation. Gain value with and without DGS is observed for compact antenna overall volume of 0.32λ0 × 0.32λ0 × 0.024λ0.

In this paper, an array antenna with asymmetric antenna fed network is presented. Total size of the proposed array antenna (with 2 × 2 elements) is 90 × 90 mm2 and distance between elements (fed by fed) is λ0/2 (λ0 = wavelength in free space). The proposed antenna is fed by coaxial cable that isolated input impedance from impedance of the array antenna feed network. The measured impedance bandwidth of the coaxial fed circular polarization array (S11 < −10 dB) is 47.9% from 4.6 to 7.5 GHz (1.63:1), and the measured 3-dB axial-ratio bandwidth is 42% from 4.7 to 7.2 GHz. The peak gain of antenna is 9.1 dBic.