A beam-deflection short backfire antenna (BD-SBA) is proposed. The BD-SBA consists of an SBA and a deflection plate. The deflection plate is designed to change the phase of the reflected waves, hence deflecting the beam of the BD-SBA. The beam deflection can realise different beam pointing within about 20°. An X-band antenna (10 GHz) with a beam pointing of 12° is fabricated and tested. The measured results demonstrate that the desired beam deflection is obtained. A gain of 14.3 dBi and a sidelobe level of −20.6 dB are realised. The BD-SBA, with a simple structure, low cost and moderately high gain, is suitable for the application of fifth-generation wireless backhauling potentially.

The frequency correlation characteristics of shadowing over television bands in a suburban area are evaluated. Some papers report that shadowing losses are high frequency correlated. However, although the frequency correlations can be modelled as a function of the frequency differences are expected, conventional works only present correlation analyses between two or three channels. The correlations have shown an exponential decrease in proportion to the frequency differences based on several massive datasets measured over the television bands. In addition, the empirical model for the characteristics of the frequency correlations is discussed. An empirical model that consists of two exponential decay models is proposed, and show the R-squared value for the experimental value is ∼1.

A very simple and fast method for the synthesis of pencil beams with linear antenna arrays of equally spaced elements is presented. The proposed procedure starts selecting the desired pencil beam as a Gaussian function. This is very convenient for two reasons: first, the continuous line-source distribution that exactly produces the desired pencil beam (i.e. the Fourier transform of it) is in turn a Gaussian function and is immediately calculated. Second, a suitable weighted sampling of this distribution gives the excitations of the array elements in closed form. Two numerical examples reveal the good performances of the proposed approach, also in comparison with the classical method by Dolph-Chebyshev. It is shown that the synthesised array factors well approximate the desired pencil beams in real time, in particular ensuring a very good behaviour in the side lobe regions. Furthermore, the ‘dynamic range ratio’ of the excitations, defined as the ratio between the maximum and the minimum amplitude of the excitations, is very low and close to unity when the array length is sufficiently small.

A hybrid waveguide/coaxial transverse magnetic (TM)/transverse electric (TE) launcher is proposed as a feeder for planar Fabry-Perot (FP) cavity antennas radiating omnidirectional beams. The structure is based on a pair of nested coaxial cables. The inner coax (TM launcher) operates on the standard TEM mode and feeds a vertical probe protruding into the antenna cavity through the ground plane. The outer coax (TE launcher) operates on the TE₀₁ mode excited by an aperture-coupled rectangular-waveguide feeding network. Geometrical symmetry ensures high isolation between the TM and TE input ports, which can be alternatively excited to achieve dual-pol operation with either horizontal or vertical linearly-polarised far field. Good impedance matching and omnidirectional dual-pol radiative features are demonstrated for an FP cavity antenna operating at 16 GHz and based on a thin periodic metal partially-reflecting surface.

To obtain low peak sidelobe level of the uniformly excited sparse planar array, a modified matrix mapping method is proposed to transform the multi-constraints optimisation problem to the unconstraint. The multiple constraints include the elements quantities, the aperture sizes and the minimum inter-elements spacing. A proportion compression function is established to meet all the constraints. Thus, the infeasible solutions can be excluded from the solutions set during the optimisation process. The simulation results show the effectiveness of the proposed method.

The expectation-maximisation (EM) algorithm uses incomplete data to get the estimation of the probabilistic model parameter, and it has been widely used in machine learning. EM techniques are applied to estimate fluorescence lifetimes in time-correlated single-photon counting based fluorescence lifetime imaging experiments without measuring the instrument response functions. The results of Monte Carlo simulations indicate that the proposed approach can obtain better or comparable accuracy and precision performances than the previously reported method.

A new RF B/H field probe for time-domain monitoring of RF electromagnetic-radiated exposure during medical device testing inside the lossy tissue-mimicking material is presented. The probe was tuned and matched for a centre frequency of 127.6 MHz to optimise the response for testing within typical 3T MRI scanners or RF exposure platforms. A 5 mm radius loop was chosen as a trade-off between spatial resolution and sensitivity and fabricated on a double-sided FR4 PCB. In the presented scheme, a low-noise RF amplifier was employed to reduce the sensitivity of the probe to induce voltage on the transmission lines and to improve accuracy. The implemented probe was found to provide acceptable spatial resolution and sensitivity for reliable B/H field mapping for this application.

Software defined radios typically employ digital filter banks (FBs) for channelisation. Frequency response masking (FRM) approach is used to reduce the computational complexity of the complex modulated FB with narrow transition band. A unified FRM-based complex modulated FB structure is proposed to design sharp filters with arbitrary passband bandwidth. The proposed unified FRM-based complex modulated FB structure with low complexity is suitable for different even-stacked or odd-stacked, maximally decimated or non-maximally decimated structures. It also can be directly applied to high sampling rate systems. It is shown that the proposed unified FRM-based complex modulated FB structure can obtain the improvement of the computational complexity compared with the other methods.

A system-level noise mitigation technique is used to design low-noise single-ended switched-capacitor filters which implement noise shaping. The performance is comparable to that of a fully differential structure, while the complexity, power dissipation and chip area are drastically reduced.

This Letter proposes an on-chip data strobe transmission circuit for dynamic random access memory (DRAM). The on-chip differential repeaters with cross-coupled latches are adopted to prevent the sampling margin reduction. A node monitoring circuit has been proposed to prevent short-circuit currents of the on-chip differential repeaters and cross-coupled latches caused by high impedance inputs. When compared with the conventional differential signalling, the proposed circuit can save the short-circuit current of 6.2 mA per a single write operation. The chip has been fabricated in 350 nm CMOS technology and the active chip area is 0.189 mm².

An on-chip 23 kHz dual-phase relaxation oscillator is presented. Charge-transfer and comparator offset cancellation techniques have been proposed to achieve low power and high temperature stability. The circuit has been designed with 0.18 μm CMOS process. The oscillator has achieved an ultra-low power of 130 nW, a supply voltage sensitivity of 0.8%/V over 1.2–1.8 V, and a temperature coefficient of 30 ppm/°C over to .

With the development of deep hashing learning, several end-to-end deep architectures have been proposed for fast image retrieval. However, learning to hash is essentially a mixed integer nonlinear optimisation problem with the non-deterministic polynomial-time (NP)-hard nature, which makes the standard back-propagation algorithm infeasible. A novel pairwise loss function with additional binary constraint via siamese network is proposed to improve the representation ability of hash codes. Compared to previous works, we force the output of each hidden node close to −1 or +1, which can produce more compact and discriminative hash codes. Extensive experimental results demonstrate that the method can generate more favourable results than existing state-of-the-art hash function learning methods with large margins.

Assessment of the quality of local estimates of data sparsity is central for various adaptive algorithms in signal processing. Empirical bounds for the estimation performance of a frequently used measure of sparsity, namely the Gini–Simpson index are derived. Confidence bounds are derived for an unbiased estimator of this measure, with exponential convergence to the true (unknown) sparsity value, as the number of samples increases. The analysis is distribution-free, as no parametric or distributional assumptions are made for the available data.

A suspended stripline (SSL) bandpass filter using a hybrid transmission line stepped impedance resonator with a transmission zero (Tz) in the higher band is proposed. The novel resonator consists of a thin inductive strip, a set of hybrid transmission lines and patch-like capacitive elements, a coupled electromagnetic field to the input lines and adjacent resonators. The characteristics of the HTLSIR have been analysed clearly. Moreover, a novel non-resonating node is introduced to generate a Tz, its position can be adjusted by changing its parameter. A detailed discussion of this effect is given, and a sample filter is designed, fabricated and tested. Both experimental results agree well with the simulations.

A wideband-balanced bandpass filter is presented using two half-wavelength transmission lines, two coupled lines and one-stepped impedance stub. Compared to the reported wideband-balanced bandpass filters, the proposed one shows the advantages of small total length, high-frequency selectivity and wideband common-mode (CM) suppression. The bandwidth of CM suppression and differential-mode transmission, and the positions of transmission zeros are controllable by the parameters. One prototype was designed, fabricated and measured with the total length of 2λ _g (λ _g is the guided wavelength at the centre frequency f ₀), 3 dB fractional bandwidth of 61% and 15 dB CM suppression bandwidth of 3.67f ₀.

A novel approach to achieve high-efficiency dual-band power amplifier (PA) is presented. Owing to the contradictions among the control of harmonics, most reported dual-band or multi-band PAs are intentionally avoiding the case when the higher-frequency band overlaps the second harmonics of the lower-frequency band, especially when . By introducing lower-frequency feedback technique a method is proposed, make a compromise between high-efficiency and power gain fluctuant, high-efficiency dual-band PA at the above condition can be achieved. To verify, a dual-band PA operating at 1.7 and 3.4 GHz is fabricated and measured. The peak output powers of the dual-band are 40.1 and 40.7 dBm with small signal gains 25 and 17 dB, and the drain efficiency at the peak output power reached 80.2 and 78.5%, respectively.

A new pathway to design floating gate quantum dot (QD) non-volatile RAM (QDNVRAM) cells that possess high-speed low-voltage Erase capabilities not possible with conventional floating gate NV memories is presented. This is achieved by directly accessing the QD floating gate layer with an additional drain (D2) during the Erase operation. Experimental data on fabricated long-channel (10 μm/14 μm) QDNVRAM cell shows ‘Erase’ pulse duration of ∼4 μs at voltage of about 10 V using drain D2 which is over two-order smaller than the ‘Write’ pulse value. Quantum mechanical simulations are also presented. QDNVRAM fabrication process is compatible with CMOS processing.

The task fundamental to quantum communication and coding is considered which consists of detecting between two possible states of a noisy qubit, with a performance assessed by the overall probability of detection error. The detection process operates in the presence of decoherence represented by a quantum thermal noise at an arbitrary temperature. With uneven prior probabilities of the two states, as the noise temperature is increased, non-monotonic evolutions are reported for the performance, which does not uniformly degrade. Regimes are found where higher noise temperatures are more favourable to detection, with relation to stochastic resonance effects where noise reveals beneficial to information processing.

The ‘commoditisation’ (i.e. using commodity hardware or commodity device as a hardware platform for network equipment) and ‘softwarisation’ (i.e. implementing the network function of the target equipment by software) have recently become big trends among communication carriers struggling to balance cost-efficiency and service flexibility. Especially in optical access networks, the concept of the commodity layer 2 (L2) switch-based passive optical network (PON) is attracting attention, but performance demonstrations have not been reported. This Letter offers the first performance demonstration of the L2 switch-based gigabit ethernet PON prototype constructed with an L2 switch and software-based PON-specific functions. The prototype achieves nearly 1 Gbps throughput in one-way transmission. Moreover, an additional numerical analysis confirms that the authors proposed architecture can accommodate sufficient PON port number.

The effect of temperature on the barrier height of a gallium arsenide (GaAs)/aluminium GaAs (AlGaAs) potential-well barrier (PWB) diodes is investigated and reported in this Letter. It was found that more electrons diffuse from the doped AlGaAs(silicon) into the undoped layers with increasing temperature, this modifies the electric field along these layers and hence the barrier height. The barrier height increases with increasing temperature at an increasing rate of – in the temperature range of 200–380 K in a similar way to the planar-doped barrier (PDB) diode. The result of the computer simulations, however, shows that the PWB diode is less sensitive than the PDB diode due to the active nature of the charge in the well.

A singular-unit restoration filter based on complex-valued neural networks that deal with spatial spectrum in interferometric synthetic aperture radar is proposed. This filter utilises more neural generalisation ability than conventional methods. In experiments, it shows a higher accuracy as well as shorter processing time than conventional real-space filters and shorter learning time than previous spectral-domain learning filters.

In high-precision relative positioning applications of global navigation satellite systems, multipath and phase centre offset/variation remain as the major coupled error sources, as they cannot be eliminated by the differential operation. A circular rotating low-cost antenna is introduced for the rover station in a constrained environment. The spatial diversity of multipath is explored by circular motion to aid the carrier-phase ambiguity resolution and error elimination. The multipath and phase centre offset are separated and estimated. Field tests demonstrate that the proposed method with low-cost antenna is able to achieve the survey-grade precision.

Most synthetic aperture radar (SAR) applies to static targets while moving targets appear unfocused in SAR images. To obtain clear images of moving targets, the Doppler parameter estimation is critical in SAR processing. However, most of the time–frequency analysis methods cannot simultaneously meet the requirements of accuracy and real time. A real-time parameter estimation algorithm based on Wigner–Ville distribution (WVD) slice and fractional Fourier transform (FrFT) is proposed. In this algorithm, the Doppler frequency rate is roughly estimated through the observed signal's WVD slices first. Then, its corresponding FrFT rotational angle is deduced and the search region is determined. Next, Doppler parameters can be accurately estimated by FrFT under the premise of reducing the computational complexity. Three reasonable choices of the slice positions are given and their estimation results are explained. SAR real data processing results indicate that the proposed algorithm can estimate Doppler parameters quickly and effectively while ensuring accuracy and providing a new way for SAR real-time parameter estimation. Finally, motion compensation in accord with the estimated parameters is also completed and focused images of several moving ship targets are obtained.

Massive multiple-input multiple-output (MIMO) has been identified as a key technology for next generation cellular systems. The performance of a multi-cellular system with large antenna arrays at the base station and single antenna user terminals, operating under a composite fading-shadowing environment are considered. The outage probability of the considered system is evaluated for the uplink transmission that uses a maximum ratio combining receiver.

A computational complexity reduction technique for space diversity-based spectrum sensing is presented. First, the received signals are combined, and a statistic for signal detection is computed from the combined signal. Phase inversion is introduced to avoid attenuation of the combined signal. As the computation of only one statistic is required regardless of the number of receive antenna, the complexity can be reduced. Numerical examples and simple analyses verify the effectiveness of the presented technique.