Several broad bandwidth, electrically small, non-Foster element-augmented antennas have been designed, analyzed and measured. Both electric loop (protractor) and electric dipole (Egyptian axe) structures have been selected as the near-field resonant parasitic (NFRP) elements for these antenna designs. In order to increase their instantaneous 10dB bandwidth, negative impedance convertor (NIC)-based capacitor and inductor elements have been designed accordingly to be incorporated internally into those NFRP elements. Proper design and analysis procedures for these systems are introduced. The simulated performance characteristics of the resulting non-Foster element-augmented protractor and Egyptian axe dipole antennas are presented. Favorable comparisons with their experimentally measured values are demonstrated.

Three dimensional (3D) terahertz (THz) imaging or THz tomography has recently proven to be useful for non-destructive testing of industrial materials and structures. In place of previous imaging techniques such as THz pulse or continuous wave (CW) radar, we propose a THz optical coherence tomography (OCT) using frequency-swept THz sources, and demonstrate 3D imaging. In addition, we further apply this technique to the millimeter-wave region in order to extend applicable targets.

We evaluated the behavior of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels using measured data. A base station for downlink or broadcast transmission requires downlink channel state information (CSI), which is outdated in time-varying environments and we encounter degraded performance due to interference. One of the countermeasures against time-variant environments is predicting channels with an autoregressive (AR) model-based method. We modified the AR prediction for a time division duplex system. We conducted measurement campaigns in indoor environments to verify the performance of the scheme of channel prediction in an actual environment and measured channel data. We obtained the bit-error rate (BER) using these data. The AR-model-based technique of prediction assuming the Jakes' model was found to reduce BER. Also, the optimum AR-model order was investigated by using the channel data we measured.

A wideband on-body antenna for a wireless body area network for an Industrial, Scientific, and Medical band is proposed. A wideband characteristic is achieved by combining two zeroth-order resonance (ZOR) modes at adjacent frequencies by controlling the value of the shunt capacitance. The size of the proposed antenna is 0.072λ0 × 0.33λ0, and the measured 10-dB return loss bandwidth is 340MHz (14.3%). In addition, the resonance frequencies operating in the ZOR mode are insensitive to the effects of the human body by virtue of the ZOR characteristic.

This paper presents design and radiation properties of a radial line microstrip antenna array (RL-MSAA) for linear polarization. A stacked circular microstrip antenna (C-MSA) is used as a radiation element for the RL-MSAA. Radiation phase of the stacked C-MSA is controlled by tuning radii of the lower and upper patches, therefore, the desired phase distribution of the RL-MSAA can be designed. In this paper, a linearly polarized RL-MSAA with three concentric rows of the stacked C-MSAs at a spacing of 0.65 wavelengths for uniform aperture distribution is designed and tested in 12GHz. The experimental results reveal that validity of the linearly polarized RL-MSAA with the stacked C-MSAs for radiation phase control is demonstrated.

A two-dimensional negative refractive index material is proposed. The material has a bulky structure composed of dielectric prism cells with metal patterns. The material is expressed by an equivalent circuit. The propagation regions of two left-handed modes calculated from the equivalent circuit exist near the propagation regions obtained by electromagnetic simulation. It is confirmed by simulation that the incident plane wave goes into the material with low reflection by using the second left-handed mode and attaching metal conversion strips around the material. A negative refractive index slab lens with 15×9 cells is made to measure the field distribution of wave out of the lens. It is shown that the resolution of the slab lens exceeds the diffraction-limit.

This paper analyzes the performance of a two-way relay network experiencing co-channel interference from multiple interferers due to aggressive frequency reuse in cellular networks. We discuss two different scenarios: Outages are declared individually for each user (individual outage) and an outage is declared simultaneously for all users (common outage). We derive the closed-form expressions for the individual and common outage probabilities of the two-way relay network with multiple interferers. The validity of our analytical results is verified by a comparison with simulation results. It is shown that the analytical results perfectly match the simulation results of the individual and common outage probabilities. Also, it is shown that the individual and common outage probabilities increase as the number of interferers increases.

A subarray signal processing scheme is described for a large-scale two-dimensional analog-digital hybrid beamformer to be used in quasi-millimeter-wave-band mobile communication systems. Multiple analog phased arrays direct their respective beams to multiple users, enabling space-division multiple access (SDMA). An iterative soft-input soft-output (SISO) multi-user detector recovers multi-user signals from subarray output signals corrupted by inter-user interference (IUI). In addition, a phased-array directivity control algorithm is derived based on inter-subarray signal phase-difference estimation from inter-beam-interference (IBI)-cancelled subarray output signals. Simulation results demonstrate that our proposed scheme achieves reduced hardware complexity, IUI-resistant multi-user signal detection, and IBI-resistant multi-user-tracking phased-array directivity control.

A microwave mammography setup for clinical testing was developed and used to successfully carry out an initial clinical test. The equipment is based on multistatic ultra wideband (UWB) radar, which features a multistatic microwave imaging via space time (MS-MIST) algorithm for high resolution and a conformal array with an aspirator for fixing the breast in place. In this paper, an outline of the equipment, a numerical simulation, and clinical test results are presented.

Folded dipole antenna with feed line (FDAFL) whose relative bandwidth is 65% (VSWR≤3) has been reported as a wideband planar antenna for a small terminal. However, this antenna is constructed outside of the ground plane (50×80mm2) by 12mm. In this study, we analyze the antenna configurations of FDAFL in 3D so that the antenna does not protrude from the ground plane as much as possible. Two different 3D antenna models derived from FDAFL are investigated. The first model is folded over the ground plane, and the second one is folded outside of the ground plane. The relative bandwidth, the VSWR characteristics and radiation patterns are studied. As a result, it is confirmed that antenna prominence could be reduced and broadband characteristics over 74% and 83% are obtained by the 3D models, respectively, which are wider than the bandwidth of conventional 2D model. Thus, FDAFL could be used in both 2D and 3D for a small terminal.

A predictive compact model of p-MOSFET negative bias temperature instability (NBTI) degradation for circuit simulation is reported with unified description of the interface-state-generation and hole-trapping mechanisms. It is found that the hole-trapping is responsible for the initial stage of the stress degradation, and the interface-state generation dominates the degradation afterwards, especially under high stress conditions. The predictive compact model with 8 parameters enables to reproduce the measurement results of the NBTI degradation under a wide range of stress bias conditions. Finally, the developed NBTI model is implemented into the compact MOSFET model HiSIM for circuit degradation simiulation.

MIMO transmission technologies have become an essential component of cellular systems such as Long Term Evolution (LTE) and LTE-Advanced. Recently, evaluating the communication performance of mobile users in cellular MIMO systems has become an urgent requirement. In this paper, we propose dynamic MIMO channel modeling for the urban environment. Our proposal is based on Geometry-based Stochastic Channel Modeling (GSCM). The cluster parameters such as the local scatterer locations around the measurement course are estimated by applying the particle filtering to measured data. We carried out radio propagation measurements in an urban environment at 3.35GHz band, and generated the dynamic channel from the measured data. The experiments showed that both the spreads and auto-correlation of Time of Arrival (ToA), Angle of Arrival (AoA) and Angle of Departure (AoD) were reconstructed within the acceptable error range in our dynamic channel model.

In this letter, a fast transmit antenna selection algorithm is proposed for the spatial-temporal combining-based spatial multiplexing ultra-wideband systems on a log-normal multipath fading channel. The presented suboptimum algorithm selects the transmit antennas associated with the largest signal to noise ratio value computed by one QR decomposition operation of the full channel matrix spatially and temporally combined. It performs the iterative channel scaling operation about the channel matrix and singular value decomposition about the channel scaled matrix. It is shown that the proposed antenna selection algorithm leads to a substantial improvement in the error performance while keeping low-complexity, and obtains almost the same error performance as the exhaustive search-based optimal antenna selection algorithm.

This letter deals with blind carrier frequency offset estimation by exploiting the minimum variance distortionless response (MVDR) criterion for interleaved uplink orthogonal frequency division multiple access (OFDMA). It has been shown that the complexity and estimation accuracy of MVDR strictly depend on the grid size used during the search. For the purpose of efficient estimation, we present an improved polynomial rooting estimator that is robust in low signal-to-noise ratio scenario. Simulation results are provided for illustrating the effectiveness of the proposed estimator.

In this paper, a novel and simple one-port de-embedding technique has been applied to through-silicon-via (TSV) characterization and modeling. This method utilized pad, via, and line structures to extract the equivalent circuit model of TSV. The main advantage of this de-embedding method is that it can reduce the chip area to fabricate test element groups (TEGs) for measurements while keeping S-parameter measurement accuracies. We also analyzed the electrical characteristics of substrate coupling and TSV equivalent impedance. Our results shows good agreements between measurement data and the equivalent circuit model up to 20GHz.

This paper describes a small size broadband fractional-N RF synthesizer for an RF test module with a high throughput and multiple resources installed in RF Automated Test Equipment (ATE) systems. The core device is the PLL-LSI composed of the 13-band asymmetrical tournament form voltage-controlled oscillators (VCOs) and the proposed 48-bit ΔΣ modulator with the infinite impulse response (IIR) filter. The single-loop PLL RF synthesizer is constructed in the form of systems in package (SiP) including the PLL-LSI and the active loop filter. The RF synthesizer SiP features a small size of 20mm × 20mm × 3mm, a high frequency resolution of smaller than 50µHz, and a phase noise of better than -110dBc/Hz at offset frequency of 1MHz across a frequency range of 100MHz to 13.4GHz. In addition, a frequency settling time of 150 µs that is faster than our conventional dual-loop PLL synthesizers using the discrete VCOs or the YIG-tuned oscillators (YTOs) is achieved. The synthesizer SiP significantly contributes to the realization of small size, high throughput RF test modules for RF ATEs.

Digital watermarking techniques have been used to assert the ownerships of digital images. The ownership information is embedded in an image as a watermark so that the owner of the image can be identified. However, many types of attacks have been used in attempts to break or remove embedded watermarks. Therefore, the watermark should be very robust against various kinds of attacks. Among them, the print-and-scan (PS) attack is very challenging because it not only alters the pixel values but also changes the positions of the original pixels. In this paper, we propose a watermarking system operating in the discrete cosine transform (DCT) domain. The polarities of the DCT coefficients are modified for watermark embedding. This is done by considering the properties of DCT coefficients under the PS attack. The proposed system is able to maintain the image quality after watermarking and the embedded watermark is very robust against the PS attack as well.

In the Knill-Laflamme-Milburn (KLM) scheme, quantum teleportation is nearly deterministically carried out with linear optics. To reconstruct an original quantum state, however, a phase shift is required for an output state. We exhibit a proper phase shift to complete quantum teleportation.

The extensive study and design of Body Area Networks (BANs) and development of related applications have been an object of interest during the last few years. Indeed, the majority of applications have been developed to operate at frequencies up to X band. However nowadays, a new growing attention is being focused on moving the study of BANs to higher frequencies such as those in V andW bands. The characterization of the on-body propagation channel is therefore essential for the design of reliable mm-wave BAN systems. However the classical methods (FDTD, MoM, FEM) commonly used at lower frequencies are not computationally efficient at mm-wave due to the large amount of mesh elements needed to discretize an electrically large geometry such as the human body. To overcome this issue, a ray tracing technique, generally used for characterizing indoor propagation, has been used to analyze a specific channel: chest-to-belt link. The reliability of this high frequency method has been investigated in this paper considering three different test cases. Moreover, a comparison of simulations and measurements, both performed on a body centric scenario at 94GHz, is also presented as well.

In terms of the transmission-line theory, a general synthesis of a new class of optimum Chebyshev-type ultra-wideband bandpass (UWB) filter prototype composed of multistage stepped-impedance resonators (SIRs) and two short-circuited shunt stubs positioned at input- and output- ports is presented. By the comparison of the real and theoretical transfer functions, the design/characteristic equations are obtained for the design of the proposed filter prototype rather than the traditional design tables. The explicit expressions of one-stage and two-stage filters are then derived and reported. Accordingly, bandpass filters with an arbitrary FBW (Fractional Bandwidth) and passband ripple can be easily designed by solving the design equations. As an example, a 10-degree Chebyshev distributed filter (two-stage filter) with an FBW of 110% is synthesized to meet FCC's outdoor mask. The synthesized circuit model are confirmed by a commercial circuit simulator and then optimized by an EM simulator, fabricated in microstrip line and characterized by the network analyzer. The good agreements between the measured and predicted frequency responses validate the effectiveness of newly proposed filter prototype and the corresponding synthesis technique. In addition, the designed filter exhibits good characteristics of comparatively low insertion loss, quite sharp skirt, very flat group delay and good stopband (especially in lower one) as well. It should be also highlighted that, compared with the conventional filters composed merely of parallel-coupled SIRs or shunt short-circuit-stubs, the new prototype can reduce the overall length of the filter by more than 3/4λg. Moreover, in terms of the presented design technique, the proposed filter prototype can be also used to easily realize the UWB filters with an FBW even greater than 110%.