A compact ultra-wideband (UWB) bandpass filter (BPF) is proposed based on end coupled microstrip transmission line, defected ground structure and defected microstrip structure. The experimental filter shows a fractional bandwidth of 110% at a centre frequency, with two observable transmission zeros (attenuation poles) at 2.1 and 11.7 GHz. Measured results exhibit an UWB passband from 3.02 to 10.6 GHz with mid-band insertion loss of 1.8 dB and group delay variation <0.45 ns. The BPF achieves a wide stopband with < −18 dB attenuation up to 20 GHz.

In this Letter, the authors propose a technique that allows a secondary user (SU) to reuse the spectrum allocated to TV broadcast system. The approach is based on protection view point and an SU is allowed to transmit outside the noise limited contour (grade B contour) with additional protection margin. An algorithm was developed that predicts the grade B contour and makes a decision on the availability of the spectrum. The keep-out distance was obtained using the existing path loss models and a model developed based on field strength measurements conducted in the very high frequency (VHF) and ultra high frequency (UHF) broadcast frequencies. Results of simulation indicate that the extra margin does not follow a linear curve as expected, but strongly depends on the operating frequency and terrain profile of the area. In addition, the measured model's prediction deviates significantly from the other models' prediction.

This paper studies design of a full-band waveguide polariser using iris for satellite communications. Operation theory and design parameters of a full-band polariser are introduced, and a systematic design method has been proposed. The performance of the polariser is analysed using the well-known commercial electromagnetic simulation software high-frequency structure simulator. Using the proposed method, a full-band polariser operating in WR-22 waveguide band (33–50 GHz) is designed, fabricated and tested. Measurements of the fabricated polariser show that the phase difference is <10° as a reference point by 90°, the axial ratio is <1.3 dB, insertion loss is <0.1 dB and return loss is >25 dB in the required overall band.

An enumerating method of complete permutation array is proposed. The list of n! permutations based on Gray code defined over finite symbol set Z_n = {1, 2, …, n} is implemented by finite state machine, named as n-RPGCF. An RPGCF can be used to search permutation code and provide improved lower bounds on the maximum cardinality of a permutation code in some cases.

The generation of nanosecond square pulse and microsecond harmonic pulse in a passively mode-locked fibre ring laser is demonstrated by inserting a 20 km long single mode fibre in the cavity. The laser operates in anomalous region based on the non-linear polarisation rotation process. The square pulse generation is because of the dissipative soliton resonance effect, which clamps the peak intensity of the laser and broadens the pulse width. The pulse width can be tuned from 28.2 to 167.7 ns. It was found that the square pulse can deliver higher pulse energy compared with the harmonic pulse. The highest recorded pulse energy is 249.8 nJ under the maximum available pump power of 125 mW without pulse breaking.

This study presents a stand-alone excitation synchronous wind power generator (SESWPG) with power flow management strategy (PFMS). The rotor speed of the excitation synchronous generator tracks the utility grid frequency by using servo motor tracking technologies. The automatic voltage regulator governs the exciting current of generator to achieve the control goals of stable voltage. When wind power is less than the needs of the consumptive loading, the proposed PFMS increases motor torque to provide a positive power output for the loads, while keeping the generator speed constant. Conversely, during the periods of wind power greater than output loads, the redundant power of generator production is charged to the battery pack and the motor speed remains constant with very low power consumption. The advantage of the proposed SESWPG is that the generator can directly output stable alternating current (AC) electricity without using additional DC–AC converters. The operation principles with software simulation for the system are described in detail. Experimental results of a laboratory prototype are shown to verify the feasibility of the system.

As the internet is fast migrating from static web pages to dynamic web pages, the users with visual impairment find it confusing and challenging when accessing the contents on the web. There is evidence that dynamic web applications pose accessibility challenges for the visually impaired users. This study shows that a difference can be made through the basic understanding of the technical requirement of users with visual impairment and addresses a number of issues pertinent to the accessibility needs for such users. We propose that only by designing a framework that is structurally flexible, by removing unnecessary extras and thereby making every bit useful (fit-for-purpose), will visually impaired users be given an increased capacity to intuitively access e-contents. This theory is implemented in a dynamic website for the visually impaired designed in this study. Designers should be aware of how the screen reading software works to enable them make reasonable adjustments or provide alternative content that still corresponds to the objective content to increase the possibility of offering faultless service to such users. The result of our research reveals that materials can be added to a content repository or re-used from existing ones by identifying the content types and then transforming them into a flexible and accessible one that fits the requirements of the visually impaired through our method (no-frill + agile methodology) rather than computing in advance or designing according to a given specification.