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This paper aims to design a dual mode X-band substrate integrated waveguide (SIW) bandpass filter in the conventional SIW structure. A pair of back-to-back square and split ring resonator is introduced in the single-layer SIW bandpass filter. The various coupling configurations of SIW bandpass filter using split square ring slot resonator is designed to obtain dual resonant mode in the passband. It is shown that the measured results agree with the simulated results to meet compact size, lower the transmission coefficient, better reflection coefficient, sharp sideband rejection and minimal group delay.

A spurious suppression of wideband response is suppressed using an open stub in the transmission line. The width and length of the stub are tuned to suppress the wideband spurs in the stopband. The measured 3 dB bandwidth is from 8.76 to 14.24 GHz with a fractional bandwidth of 48.04% at a center frequency of 11.63 GHz, 12.59 GHz. The structure is analyzed using the equivalent circuit model, and the simulated analysis is based on an advanced design system software.

This paper discusses the characteristics of resonator below the waveguide cut-off frequency with their working principles and applications. Considering the difficulties in combining the resonators with a metallic waveguide, a new guided wave structure – the SIW is designed, which is synthesized on a planar substrate with linear periodic arrays of metallized via based on the printed circuit board.

This study has investigated the wave propagation problem of the SIW loaded by square ring slot-loaded resonator. The electric dipole nature of the resonator has been used to achieve a forward passband in a waveguide environment. The proposed filters have numerous advantages such as high-quality factor, low insertion loss, easy to integrate with the other planar circuits and, most importantly, compact size.

On average, a medium-sized satellite consist of almost 500 sensors where powering these sensors in space in such an unreachable environment is critical. Backing this, a compact energy harvester for powering up distant sensors is discussed here is the purpose of this paper. This is in line with the geostationary satellite-powered using the available electromagnetic energy on the satellite panels in space.

The designed rectenna makes use of a compact wideband receiving antenna operating at the targeted frequency band from 8 to 18 GHz. It also consists of a simple dual diode rectifier topology with a matching circuit, bandpass filter and a resistive load to convert the received radio frequency energy into usable direct current (DC) voltage.

The rectenna measurement is performed using three different configuration setups. This shows that a maximum DC voltage of 1.8 V and 5-10 mV is harvested from rectifier and rectenna (includes antenna and rectifier) when 20 dBm power is transmitted from the transmitting antenna operating at X and Ku band. This makes the rectenna feasible to power wireless sensors in a structural health monitoring system.

The measurements are performed by considering a real-time environment in space in terms of the distance between the transmitting and receiving antenna, which depends on the far-field of the transmitting antenna in a satellite.

All over the world, Bangladesh is well known as a flood- and cyclone-affected country. But in the recent years the slow onset disaster of drought is more frequent in Bangladesh due to climatic as well as nonclimatic variability. As a consequence, agriculture along with its dependent farmers’ livelihoods tremendously experience its adverse impacts. Therefore, the main focus of this chapter is to discuss about drought, its effects on different sectors, and how in different levels a number of drought risk management actions are carried out to cope with this insidious disaster in the context of Bangladesh.

Water insecurity is a big threat and a defining global challenge that causes social dilemma in the society. Analyzing all the previous chapters in this volume, this final chapter will discuss water use and its consequence of social dilemma, the key lessons and observations that trigger water insecurity, major challenges and success factors toward water insecurity, and how water insecurity can be minimized through the involvement of community people, and improvement of social stability in the form of common understanding. This chapter also emphasizes the linkage between local and national levels by the development of Integrated Water Resource Management both in quantity and quality aspects.

Of all the natural disasters, drought is the most gradual and the most hard to predict. However, this insidious disaster continually affects the lives and livelihoods of farmers living in drought-affected areas. The northwestern part of Bangladesh is recognized as being more severely affected by drought than the rest of the country, as drought is a recurring event in this area. It has substantial impacts on agriculture and causes great suffering for farmers – in particular, poor and small farmers, who are more vulnerable to drought. Therefore, this study tries to illustrate farmers’ existing coping practices with regard to drought. It also addresses their prioritized adaptation practices, which are based on local context and available resources. This study not only focuses on the implementation of these adaptation practices from the national to the local level, but it also mentions various roles of stakeholders and a definite timeframe for each adaptation practice.

The northwestern region of Bangladesh has experienced drought more in recent years than earlier decades because of high rainfall variability accompanied by high temperature. As Bangladesh is an agro-based country, agriculture and its dependent farmers’ livelihood face substantial impacts. To cope with drought, farmers of this region performed various adaptation measures by their own efforts along with institutional support. But these efforts and support are not sufficient enough for them to endure drought. Therefore, this chapter discloses how to measure drought-affected areas and identify action-oriented drought-adaptive practices of farmers that will enhance drought risk management policy and actions in northwestern Bangladesh.

Salinity is one of the major problems in the coastal region of Bangladesh that contributes to 20% of the total land area. About 53% of the coastal region is affected by different degrees of salinity. Salinity intrusion in this area is mainly derived through climate change as well as anthropogenic factors that make this region more vulnerable. Hence, salinity intrusion has adverse effects on water, soils, agriculture, fisheries, ecosystem, and livelihoods of this region. To ensure the availability of food as well as drinking water, this chapter highlights how individual and community people have endeavored several adaptation measures to minimize salinity effects. Moreover, it further discloses governmental and other development organizations’ actions toward salinity to reduce its impacts.

Case studies from many countries indicate that even when rainfall is high drought can still occur. Droughts have been recorded in Bangladesh, where the rainfall is 2,300mm per year, and in Luang Prabang, Laos, where the annual rainfall is 3,200mm. Similarly, the highest Standardized Precipitation Index (SPI) value of 2.78 indicates a possibility of floods in Cambodia. Identification of a threshold SPI value is necessary to pinpoint impending drought. Since SPI values reflect only the rainfall situation and not the existing water availability in reservoirs and canal systems, such a detailed impact-assessment study should also compare the duration of a negative SPI value with that of reduction in the available water from various sources, including groundwater, reservoirs, and canal irrigation systems. So drought occurs not only because of lack of rainfall but also because of bad practices of water usage and water management.