2006 IEEE Antennas and Propagation Society International Symposium, 2006
A novel frequency selective surface (FSS) absorber is presented for 5 GHz WLAN applications. It c... more A novel frequency selective surface (FSS) absorber is presented for 5 GHz WLAN applications. It consists of a conventional conducting cross-dipole FSS and a matching resistive FSS. This thin configuration has shown good stopband and absorption characteristics for 5 GHz WLAN signals while allowing 900/1800/1900 MHz mobile signals to pass through almost unattenuated. Preliminary theoretical results on absorption and transmission
2010 IEEE Antennas and Propagation Society International Symposium, 2010
A switchable frequency selective surface (FSS) designed to operate as a free space amplitude shif... more A switchable frequency selective surface (FSS) designed to operate as a free space amplitude shift keying (ASK) modulator at 60 GHz is presented. The FSS is based on rectangular loop aperture geometry, with each unit cell having two PIN diodes across the aperture at 180 degree interval. This makes the FSS operate in only one polarization i.e. either TE or
2011 IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications, 2011
A band-pass frequency selective surface (FSS) which is designed on energy saving glass (ESG) with... more A band-pass frequency selective surface (FSS) which is designed on energy saving glass (ESG) with a layer of hard coating to improve the transmission of RF/Microwave signals through modern buildings is presented. A square loop and top loaded cross dipoles FSSs are combined to produce a dual band-pass filter, to improve the transmission of the most common UMTS and Wi-Fi signals, while maintaining the IR insulation properties of the ESG. An optimized design is presented, which attenuates less than 10 dB within the required microwave bands, while only reducing both the total coating area and IR attenuation by 12.35%. A stable response is achieved between 0° – 60° incident angles, for both TE and TM polarizations. Parametric studies on geometrical dimensions, substrate permittivity and thickness also help clarify the effects of these parameters upon the overall performance of FSS on hard coating ESG and the process of FSS design optimization.
Abstract This paper presents a dual-bandpass (DBP) frequency selective surface (FSS) based on har... more Abstract This paper presents a dual-bandpass (DBP) frequency selective surface (FSS) based on hard-coating energy saving glass (ESG). The objective of this study is to generate a novel design of FSS on ESG, which is to be used for future energy smart buildings at ...
IEEE Transactions on Antennas and Propagation, 2007
Oblique incidence performance of a novel two-layer absorb/transmit frequency selective surface (F... more Oblique incidence performance of a novel two-layer absorb/transmit frequency selective surface (FSS) is investigated. The FSS has good frequency stability for both horizontally and vertically polarized waves incident normally or at oblique angles. Due to its transmission for 900/1800/1900 MHz mobile bands and good absorption for 5 GHz waves, it has the potential as a security wall or isolator for
IEEE Transactions on Antennas and Propagation, 2000
ABSTRACT Energy-saving glass is becoming very popular in building design due to their effective s... more ABSTRACT Energy-saving glass is becoming very popular in building design due to their effective shielding of building interior against heat entering the building with infrared (IR) waves. This is obtained by depositing a thin layer of metallic-oxide on the glass surface using special sputtering processes. This layer attenuates IR waves and hence keeps buildings cooler in summer and warmer in winter. However, this resistive coating also attenuates useful microwave/RF signals required for mobile phone, GPS and personal communication systems etc. by as much as 30 dB. To overcome this drawback, a bandpass aperture type cross-dipole frequency selective surface (FSS) is designed and etched in the coatings of energy-saving glass to improve the transmission of useful signals while preserving IR attenuation as much as possible. With this FSS, 15-18 dB peak transmission improvement can be achieved, for waves incident with ±45° from normal for both TE and TM polarizations. Theoretical and measured results are presented.
IEEE Transactions on Antennas and Propagation, 2000
A frequency selective surface (FSS) that is electronically switchable between reflective and tran... more A frequency selective surface (FSS) that is electronically switchable between reflective and transparent states is tested. It can be used to provide a spatial filter solution to reconfigure the electromagnetic architecture of buildings. The FSS measurements show that the frequency response of the filter does not change significantly when the wave polarization changes or the angle of incidence changes up
Active Frequency Selective Surfaces (FSS) have been used as spatial filters for microwave frequen... more Active Frequency Selective Surfaces (FSS) have been used as spatial filters for microwave frequencies over decades (1). In most cases, achieving stable performance at oblique angles is a challenge. In this paper an active FSS design is presented for 2.45 GHz WLAN. It shows good angle of incidence stability for perpendicular polarization.
ABSTRACT An inherent transmission problem associated with modern energy-saving glass windows is a... more ABSTRACT An inherent transmission problem associated with modern energy-saving glass windows is analyzed. These windows are used in building design to provide thermal insulation which keeps the interior warmer in the winter and cooler in the summer. This thermal insulation is achieved by employing a very thin layer of metallic oxide on one side of the ordinary (float) glass. This layer attenuates infrared waves while remaining transparent to ultraviolet frequencies. But this metallic oxide coating also attenuates the transmission of useful RF/microwave signals (GSM, GPS etc) through the glass window. We have investigated the transmission of microwave frequencies through OptithermtradeSN glass window manufactured by Pilkington. At average, about 30 dB attenuation is observed from 800 MHz to 6 GHz for both TE and TM polarizations at normal incidence. Theoretical and measured results are presented.
2006 IEEE Antennas and Propagation Society International Symposium, 2006
A novel frequency selective surface (FSS) absorber is presented for 5 GHz WLAN applications. It c... more A novel frequency selective surface (FSS) absorber is presented for 5 GHz WLAN applications. It consists of a conventional conducting cross-dipole FSS and a matching resistive FSS. This thin configuration has shown good stopband and absorption characteristics for 5 GHz WLAN signals while allowing 900/1800/1900 MHz mobile signals to pass through almost unattenuated. Preliminary theoretical results on absorption and transmission
2010 IEEE Antennas and Propagation Society International Symposium, 2010
A switchable frequency selective surface (FSS) designed to operate as a free space amplitude shif... more A switchable frequency selective surface (FSS) designed to operate as a free space amplitude shift keying (ASK) modulator at 60 GHz is presented. The FSS is based on rectangular loop aperture geometry, with each unit cell having two PIN diodes across the aperture at 180 degree interval. This makes the FSS operate in only one polarization i.e. either TE or
2011 IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications, 2011
A band-pass frequency selective surface (FSS) which is designed on energy saving glass (ESG) with... more A band-pass frequency selective surface (FSS) which is designed on energy saving glass (ESG) with a layer of hard coating to improve the transmission of RF/Microwave signals through modern buildings is presented. A square loop and top loaded cross dipoles FSSs are combined to produce a dual band-pass filter, to improve the transmission of the most common UMTS and Wi-Fi signals, while maintaining the IR insulation properties of the ESG. An optimized design is presented, which attenuates less than 10 dB within the required microwave bands, while only reducing both the total coating area and IR attenuation by 12.35%. A stable response is achieved between 0° – 60° incident angles, for both TE and TM polarizations. Parametric studies on geometrical dimensions, substrate permittivity and thickness also help clarify the effects of these parameters upon the overall performance of FSS on hard coating ESG and the process of FSS design optimization.
Abstract This paper presents a dual-bandpass (DBP) frequency selective surface (FSS) based on har... more Abstract This paper presents a dual-bandpass (DBP) frequency selective surface (FSS) based on hard-coating energy saving glass (ESG). The objective of this study is to generate a novel design of FSS on ESG, which is to be used for future energy smart buildings at ...
IEEE Transactions on Antennas and Propagation, 2007
Oblique incidence performance of a novel two-layer absorb/transmit frequency selective surface (F... more Oblique incidence performance of a novel two-layer absorb/transmit frequency selective surface (FSS) is investigated. The FSS has good frequency stability for both horizontally and vertically polarized waves incident normally or at oblique angles. Due to its transmission for 900/1800/1900 MHz mobile bands and good absorption for 5 GHz waves, it has the potential as a security wall or isolator for
IEEE Transactions on Antennas and Propagation, 2000
ABSTRACT Energy-saving glass is becoming very popular in building design due to their effective s... more ABSTRACT Energy-saving glass is becoming very popular in building design due to their effective shielding of building interior against heat entering the building with infrared (IR) waves. This is obtained by depositing a thin layer of metallic-oxide on the glass surface using special sputtering processes. This layer attenuates IR waves and hence keeps buildings cooler in summer and warmer in winter. However, this resistive coating also attenuates useful microwave/RF signals required for mobile phone, GPS and personal communication systems etc. by as much as 30 dB. To overcome this drawback, a bandpass aperture type cross-dipole frequency selective surface (FSS) is designed and etched in the coatings of energy-saving glass to improve the transmission of useful signals while preserving IR attenuation as much as possible. With this FSS, 15-18 dB peak transmission improvement can be achieved, for waves incident with ±45° from normal for both TE and TM polarizations. Theoretical and measured results are presented.
IEEE Transactions on Antennas and Propagation, 2000
A frequency selective surface (FSS) that is electronically switchable between reflective and tran... more A frequency selective surface (FSS) that is electronically switchable between reflective and transparent states is tested. It can be used to provide a spatial filter solution to reconfigure the electromagnetic architecture of buildings. The FSS measurements show that the frequency response of the filter does not change significantly when the wave polarization changes or the angle of incidence changes up
Active Frequency Selective Surfaces (FSS) have been used as spatial filters for microwave frequen... more Active Frequency Selective Surfaces (FSS) have been used as spatial filters for microwave frequencies over decades (1). In most cases, achieving stable performance at oblique angles is a challenge. In this paper an active FSS design is presented for 2.45 GHz WLAN. It shows good angle of incidence stability for perpendicular polarization.
ABSTRACT An inherent transmission problem associated with modern energy-saving glass windows is a... more ABSTRACT An inherent transmission problem associated with modern energy-saving glass windows is analyzed. These windows are used in building design to provide thermal insulation which keeps the interior warmer in the winter and cooler in the summer. This thermal insulation is achieved by employing a very thin layer of metallic oxide on one side of the ordinary (float) glass. This layer attenuates infrared waves while remaining transparent to ultraviolet frequencies. But this metallic oxide coating also attenuates the transmission of useful RF/microwave signals (GSM, GPS etc) through the glass window. We have investigated the transmission of microwave frequencies through OptithermtradeSN glass window manufactured by Pilkington. At average, about 30 dB attenuation is observed from 800 MHz to 6 GHz for both TE and TM polarizations at normal incidence. Theoretical and measured results are presented.
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Papers by Dr Ghaffer Kiani