Dual-band Filtenna Array for WLAN Applications

This paper presents the design and results of a dual-band antenna array integrated with bandpass filters for WLAN applications. The array is fed with a single 50 Ω port and consists of two radiating elements; thereby having a 1x2 array structure. The two bands of the antenna array correspond to the two WLAN bands of 2.4 GHz and 5.8 GHz. A standalone array has first been designed. Other than the two fundamental resonant frequencies, the standalone array exhibits spurious harmonics at various other frequencies. For the suppression of these harmonics, the array has been integrated with two bandpass filters, centered at 2.4 GHz and 5.8 GHz. The resulting filtenna array was simulated, fabricated and measured. Obtained simulation and measurement results agree well with each other and have been presented to validate the accuracy of the proposed structure. Measured return loss of the structure shows dual-bands at 2.4 GHz and 5.8 GHz of more than 30 dB each and also a successful suppression of the spurious harmonics of the antenna array has been achieved. Radiation patterns have also been simulated and measured and both results shown. The gain and efficiency have also been presented; with the values being 6.7 dBi and 70% for the 2.4 GHz band and 7.4 dBi and 81% for the 5.8 GHz band respectively.

Methods for the transfer function design of multiple narrow-band bandpass sigma-delta modulators

This paper presents the design analysis of novel tunable narrow-band bandpass sigma-delta modulators, which can achieve concurrent multiple noise-shaping for multi-tone input signals. Four different design methodologies based on the noise transfer functions of comb filters, slink filters, multi-notch filters and fractional delay comb filters are applied for the design of these multiple-band sigma-delta modulators. The latter approach utilises conventional comb filters in conjunction with FIR, or allpass IIR fractional delay filters, to deliver the desired nulls for the quantisation noise transfer function. Detailed simulation results show that FIR fractional delay comb filter-based sigma-delta modulators tune accurately to most centre frequencies, but suffer from degraded resolution at frequencies close to Nyquist. However, superior accuracies are obtained from their allpass IIR fractional delay counterpart at the expense of a slight shift in noise-shaping bands at very high frequencies. The merits and drawbacks of each technique for the various sigma-delta topologies are assessed in terms of in-band signal-to-noise ratios, accuracy of tunability and coefficient complexity for ease of implementation.

On absence: society’s return to barbarians

The problem of social exclusion is dealt here through the lens of a particularly radical social theory, that of autopoietic society by Niklas Luhmann. Here, exclusion is included in society, no longer as an issue for care, integration and therapy, but as a mechanism to show the importance of the visibility of exclusion. The inclusion of exclusion in autopoiesis is a far-reaching step that demands a revisiting of the concept of autopoietic society. This article proposes a radicalization of the concept on the basis of an acknowledgment of the impossibility of communication with the excluded. This acknowledgement conditions society from within. It is built upon the Luhmannian description of Barbarism as the included exclusion, and is further conceptualized as its excess, as a 'space of absence'. Within autopoiesis, absence is described as an aporetic rather than a paradoxical structure, a memento vanitas that irritates the system from within, constantly reminding it of its limitations.

Narrow-band variable center frequency single-loop and multistage sigma-delta modulators for bandpass signals

Oversampled narrow-band single-loop and multistage resonator-based bandpass sigma-delta (Σ-Δ) modulators that can accommodate different passband center to sampling frequency ratios are reported. These tunable bandpass configurations are designed by analytically determining and subsequently verifying through detailed empirical simulations the required compensation hardware to deliver enhanced noise-shaping. It is demonstrated that comparatively superior in-band signal-to-noise ratios and dynamic ranges are attributed to the inclusion of appropriate digital feedforward and feedback compensators within these structures.

Application of fractional delay filters to tune the centre frequency location of single-band sigma-delta modulators

This paper presents a novel technique for the design of narrow-band sigma-delta modulators with an embedded tunable centre frequency mechanism. This method demonstrates that the use of sum filters combined with a fractional delayer provide the flexibility of tuning the noise shaping band for any desired variable centre frequency input signal.

A comparative study of complex multiple-band noise-shaping sigma-delta modulators for multi-tone input signals

This paper presents a comparative study of complex single-bit and multi-bit sigma-delta modulators that are capable of providing concurrent multiple-band noise-shaping for multi-tone narrow-band input signals. The concepts applied for the three design methodologies are based on the noise transfer functions of complex comb, complex slink and complex multi-notch filters.

Increasing the variability of centre frequency locations in multiple-band sigma-delta modulators via the use of fractional delay filters

This paper presents the design analysis of novel tunable narrow-band bandpass sigma-delta modulators, that can achieve concurrent multiple noise-shaping for multi-tone input signals. This approach utilises conventional comb filters in conjunction with FIR, or allpass IIR fractional delay filters, to deliver the desired nulls for the quantisation noise transfer function. Detailed simulation results show that FIR fractional delay comb filter based sigma-delta modulators tune accurately to most centre frequencies, but suffer from degraded resolution at frequencies close to Nyquist. However, superior accuracies are obtained from their allpass IIR fractional delay counterpart at the expense of a slight shift in noise-shaping bands at very high frequencies.

How does a house remember? heritage-ising return migration in an Indonesian-Chinese house museum in Guangdong, PRC

This paper is an attempt to integrate heritage and museum studies through exploring the complex relationship between the materiality of architecture and social memories with a house museum of return migration in Guangdong, PRC as a case study. It unveils that the ongoing process of memory is intrinsically intertwined with spatial and temporal dimensions of the physical dwelling and built environment and the wider social-historical context and power relations shaping them. I argue that it is the house as ‘object of exhibit’ just as much as the exhibits inside the house that materialises the turbulent and traumatic migratory experience of Returned Overseas Chinese, embodies their memories and exposes the contested nature of museumification. By looking at the socially and geographically marginalised dwelling of return migrants, the house draws people’s attention to the often neglected importance of conceptual periphery in re-theorising what is often assumed to be the core of heritage value. It points to the necessity to integrate displaced, diasporic, transnational subjects to heritage and museum studies that have been traditionally framed within national and territorial boundaries.

Churchill as Chancellor of the Exchequer (1924–9) and the return to the gold standard

The general election of 29 October 1924 saw Winston Churchill return to Parliament as Constitutionalist MP for Epping after two years in the political wilderness. It also saw Stanley Baldwin swept back to Number 10 on a Conservative landslide. Speculation about whether Baldwin would cement Churchill’s drift from the Liberal fold by offering him office surfaced during the election campaign. Churchill nevertheless thought ‘it very unlikely that I shall be invited to join the Government, as owing to the size of the majority it will probably be composed only of impeccable Conservatives’. [ 1 ] Because of his anti-socialist credentials, his ability to reassure wavering Liberals through his opposition to protectionism – dropped by Baldwin after its rejection in the 1923 general election – and concern he could prove a rallying point for backbench malcontents, there was however much to commend giving Churchill a post. To his surprise, Baldwin offered Churchill the long-coveted office of Chancellor of the Exchequer, briefly held by his father before his ill-conceived resignation in 1887. Having arranged a meeting with his Labour predecessor, Philip Snowden, about outstanding business the new Chancellor set to work. Marking his political transition, a few days later Churchill resigned from the National Liberal Club.

Cross-Industry Product Diversification and Contagion in Risk and Return: The Case of Bank-Insurance and Insurance-Bank Takeovers

We investigate the impact of domestic/international bancassurance deals on the risk-return profiles of announcing and non-announcing banks and insurers within a GARCH model. Bank-insurance deals produce intra- and inter-industry contagion in both risk and return, with larger deals producing greater contagion. Bidder banks and peers experience positive abnormal returns, with the effects on insurer peers being stronger than those on bank peers. Insurance-bank deals produce insignificant excess returns for bidder and peer insurers and positive valuations for peer banks. Following the deal, the bank bidders’ idiosyncratic (systematic) risk falls (increases), while insurance bidders exhibit a lower systematic risk and maintain their idiosyncratic risk.

Winston Churchill as Chancellor of the Exchequer (1924-9) and the Return to the Gold Standard

This revisits Churchill's decision, as Chancellor of the Exchequer 1924-29, to restore the Gold Standard in 1925. This is considered within the wider context of the overall aims of Churchill's policies, including his efforts to: tackle Anglo-American economic and financial relations in the aftermath of the Great War; address budgetary pressures; widen the tax base through innovations such as the Betting Duty; spread the social burden of taxes; and revive the economy, not least through his de-rating scheme.