Miniaturised bandpass filters for wireless communications

The wireless industry has seen exceptional development over the past few decades due to years of sustained military and commercial enterprise. While the electromagnetic spectrum is becoming increasingly congested, there is a growing tendency to strive for higher bandwidths, faster throughputs, greater versatility, compatibility and interoperability in current and emerging wireless technologies. Consequently, an increasingly stringent specification is imposed upon the frequency utilization of wireless devices. New challenges are constantly being discovered in the development and realization of RF and microwave filters, which have not only sustained but fuelled microwave filter research over the many years. These developments have encouraged new solutions and techniques for the realization of compact, low loss, highly selective RF and microwave bandpass filters. The theme of this dissertation is the realization of planar compact performance microwave and RF bandpass filters for wireless communication systems. The work may be broadly categorised into three sections as follows. The first section presents a novel compact planar dual-mode resonator with several interesting and attractive features. Generally, planar microwave dual-mode resonators are known to half the filter footprint. However, it is found that the proposed resonator is capable of achieving further size reductions. In addition the resonator inherently possesses a relatively wide stopband as the lowest spurious harmonic resonance is observed at thrice the fundamental frequency. Properties of this resonator, such as these and more are explored in depth to arrive at an accurate electrical equivalent circuit, which is used as the basis for high order filter design. The application of these resonators in the design of bandpass filters is the subject of the second section. A general filter design procedure based on the equivalent circuit is presented to assist the design of all-pole filters. Alternatively, it is shown that generalised Chebyshev filters with enhanced selectivity may be developed with cross coupled resonator topologies. The discussions are supplemented with detailed design examples which are accompanied by theoretical, simulated and experimental results in order to illustrate the filter development process and showcase practical filter performance. The third section explores the possibility of employing these resonators in the development of frequency tunable bandpass filters. Preference is given to varactor diodes as the tuning element due to the numerous qualities of this device in contrast to other schemes. In particular, interest is paid to center frequency tuned filters with constant bandwidth. Tunable filters constructed with the dual-mode resonator are shown to have a relatively wide tuning range as well as significantly higher linearity in comparison to similar published works. In line with the previous section, experimental verification is presented to support and supplement the discussions

Demand for electricity: evidence of cointegration and causality from Sri Lanka

This study examines the cointegration and causality relationship between the demand for residential electricity and real income, average real electricity prices, real kerosene prices and real gas prices using annual data for the period, 1960-2007 in Sri Lanka. Error correction (EC) techniques and the Granger-causality (GC) approaches are employed. The long run income elasticity of demand, price elasticity of demand and kerosene price were estimated to be 0.78, -0.62, and 0.14 respectively. The short run elasticities for the same variables were 0.32, -0.16 and 0.10 respectively. The GC results detect bi-directional causality between electricity consumption and real income as well as electricity prices and its consumption. This suggests that these variables are determined jointly. Furthermore, one-way causality running from kerosene price to electricity demand was also found.Electricity demand, causality, cointegration analysis

The domestic financial market and the trade liberalization outcome : the evidence from Sri Lanka

The authors developed a framework for analyzing the relationship between domestic financial markets and the effects of trade liberalization and applied it to Sri Lanka's experience between 1977 and 1987. They found that the domestic financial market significantly affects the outcome of trade liberalization. Because Sri Lanka deregulated its interest rates when it undertook the trade liberalization, this allowed those earning more from trade liberalization to hold financial assets rather than nontradables. The availability of savings and time deposits at attractive interest rates prevented the premature appreciation of the exchange rate, thus helping to maintain the competitiveness stimulated by trade liberalization. By reforming interest rates, removing credit ceilings, and increasing competition among banks, Sri Lanka helped increase private sector savings - which could be reallocated to the tradable sector. Unlike earlier studies on financial reform in Sri Lanka, this one finds that financial reforms have increased private savings in financial institutions, raised economywide financial intermediation ratios, and expanded credit to the private sector. More important, the authors find a statistically significant relationship between the financial intermediation ratio and the real exchange rate.Banks&Banking Reform,Financial Intermediation,Insurance&Risk Mitigation,Economic Theory&Research,Environmental Economics&Policies

Estimating short and long-term residential demand for electricity: New evidence from Sri Lanka

This study investigates the short-run dynamics and long-run equilibrium relationship between residential electricity demand and factors influencing demand - per capita income, price of electricity, price of kerosene oil and price of liquefied petroleum gas - using annual data for Sri Lanka for the period, 1960-2007. The study uses unit root, cointegration and error correction models. The long-run demand elasticities of income, own price and price of kerosene oil (substitute) were estimated to be 0.78, - 0.62, and 0.14 respectively. The short-run elasticities for the same variables were estimated to be 0.32, -0.16 and 0.10 respectively. Liquefied petroleum (LP) gas is a substitute for electricity only in the short-run with an elasticity of 0.09. The main findings of the paper support the following (1) increasing the price of electricity is not the most effective tool to reduce electricity consumption (2) existing subsidies on electricity consumption can be removed without reducing government revenue (3) the long-run income elasticity of demand shows that any future increase in household incomes is likely to significantly increase the demand for electricity (4) any power generation plans which consider only current per capita consumption and population growth should be revised taking into account the potential future income increases in order to avoid power shortages in the country.

The International Allocation of R&D Activity by US Multinationals: The East Asian Experience in Comparative Perspective

This paper examines patterns and determinants of overseas R&D expenditure of MNEs, with emphasis on the East Asian experience, using a new panel dataset relating to US-based manufacturing MNEs over the period 1990-2001. It is found that inter-country differences in R&D intensity of operation of US MNE affiliates are fundamentally determined by the domestic market size, overall R&D capability and cost of hiring R&D personnel. The impact of domestic market orientation of affiliates on R&D propensity varies among countries depending on their stage of global economic integration. Intellectual property protection seems to matter largely for mature economies with complementary endowments. There is no evidence to suggest that financial incentives have a significant impact on inter-country differences in R&D intensity when controlled for other relevant variables. Nor is there a statistically significant relationship between the size of the capital stock of MNEs and R&D intensity of their operation across countries. Overall, our findings serve as a caution against paying too much attention by host country governments on turning MNEs affiliates into technology creators as part of their foreign direct investment policy.

East Asia in World Trade: The Decoupling Fallacy, Crisis, and Policy Challenges

This paper examines the export experience of China and other East Asian economies in the aftermaths of the global financial crisis against the backdrop of pre-crisis trade patterns. The analysis is motivated by the ‘decoupling’ thesis, which was a popular theme in the Asian policy circles in the lead-up to the onset of the recent financial crisis, and aims to probe three key issues: Was the East Asian trade integration story that underpinned the decoupling thesis simply a statistical artifact or the massive export contraction caused by an overreaction of traders to the global economic crisis and/or by the drying up of trade credit, which overpowered the cushion provided by intra-regional trade? What are the new policy challenges faced by the East Asian economies? Is there room for an integrated policy response that marks a clear departure from the pre-crisis policy stance favoring export-oriented growth? The findings caution against a possible policy backlash against openness to foreign trade arising from the new-found enthusiasm for rebalancing growth, and make a strong case for a long-term commitment to non-discriminatory multilateral and unilateral trade liberalization.global financial crisis, global production sharing, production networks, China

Global Production Sharing, Trade Patterns, and Determinants of Trade Flows in East Asia

Global production sharing—the breakup of a production process into vertically separated stages that are carried out in different countries—has become one of the defining characteristics of world trade over the past few decades. Any analysis of trade patterns or its determinants that ignores this phenomenon, and the trade in parts and components that it generates, is likely to result in erroneous conclusions. This study examines the extent and pattern of these flows, focusing on East Asia, and probes its implications for the analysis of the determinants of trade flows. World trade in parts and components increased from about 18.9% to 22.3% of total exports between 1992/93 and 2005/06. Most of this growth emanates from East Asia, with its share in total world exports increasing from 27% to 39% over the same period. There was a notable decline in Japan’s share toward the end of this period, but this was more than offset by the rising importance of the People's Republic of China (PRC). In East Asia, most of this trade is in electronics. The econometric analysis reveals that parts and components are remarkably less sensitive to changes in relative prices; as a result, the sensitivity of aggregate trade flows to relative price changes diminishes as its share increases. This implies that exchange rate policy may be less effective in balance of payments adjustment, in countries where component trade is high and growing.Global production sharing; product fragmentation trade; determinants of trade flows; exchange rate policy

Distortions to Agricultural Incentives in Malaysia

Distorted incentives, agricultural and trade policy reforms, national agricultural development, Agricultural and Food Policy, International Relations/Trade, F13, F14, Q17, Q18,

Why do policy decision-makers opt for command and control environmental regulation? An economic analysis with special reference to Sri Lanka

This chapter examines why policy decision-makers opt for command and control environmental regulation despite the availability of a plethora of market-based instruments which are more efficient and cost-effective. Interestingly, Sri Lanka has adopted a wholly command and control system, during both the pre and post liberalisation economic policies. This chapter first examines the merits and demerits of command and control and market-based approaches and then looks at Sri Lanka’s extensive environmental regulatory framework. The chapter then examines the likely reasons as to why the country has gone down the path of inflexible regulatory measures and has become entrenched in them. The various hypotheses are discussed and empirical evidence is provided. The chapter also discusses the consequences of an environmentally slack economy and policy implications stemming from adopting a wholly regulatory approach. The chapter concludes with a discussion of the main results.Command and control vs market-based instruments, Environmental and health effects, Economic analysis, Policy implications

Miniaturised microstrip dipexers for WiMAX applications

Miniaturised microstrip diplexer and bandpass filters using single ring resonators with good transmission and reflection characteristics on each channel for WiMAX applications have been presented. The size of the proposed diplexer is reduced. The diplexer is easy to manufacture and the results are easily reproducible. The improvement of the performance of diplexer through introduction of additional transmission zeros is under investigation