Chapter 2
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CHAPTER‐2
Chapter2 Literature review 2. 2.1
Mobile Communication Evolution and Multiband Antennas Introduction The literature review shows some descriptions of the low profile antenna
especially about the multiband frequencies that they can operate at GSM900, DCS1800, PCS1900, and UMTS2000.It also study the performance of them in terms of input impedance, field patterns and gain. A number of papers explaining the different types of multiband antennas for multiple frequencies are presented here.
2.2 The Evolution of Mobile Telephone Systems Cellular is one of the fastest growing and most demanding telecommunications applications. Today, it represents a continuously increasing percentage of all new telephone subscriptions around the world. Over the last 12 years, the telecommunication/ICT sector has undergone major changes. With high growth in the mobile sector, mobile penetration rates stood at more than 40 percent at the end of 2006. ITU data suggest that the number of mobile cellular subscribers surpassed the 3 billion mark in August 2007. At current growth rates, global mobile penetration is expected to reach 50 percent by early 2008. Despite major differences between the developed and the developing world, mobile services have been critical in enhancing access to telecommunications in many developing regions and rural areas, where fixed lines remain limited or non‐ existing [51]. The concept of cellular service is the use of low‐power transmitters where frequencies can be reused within a geographic area.
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CHAPTER‐2
2.3 Historical Review The idea of cell‐based mobile radio service was formulated in the United States at Bell Labs in the early 1970s. However, the Nordic countries were the first to introduce cellular services for commercial use with the introduction of the Nordic Mobile Telephone (NMT) in 1981. Cellular systems began in the United States with the release of the advanced mobile phone service (AMPS) system in 1983. The AMPS standard was adopted by Asia, Latin America, and Oceanic countries, creating the largest potential market in the world for cellular. In the early 1980s, most mobile telephone systems were analog rather than digital, like today's newer systems. One challenge facing analog systems was the inability to handle the growing capacity needs in a cost‐efficient manner. As a result, digital technology was welcomed. The advantages of digital systems over analog systems include ease of signaling, lower levels of interference, integration of transmission and switching, and increased ability to meet capacity demands.
2.4 Different Designs Available on Literature: 2.4.1 Design of a Multiband Internal Antenna for Third Generation Mobile Phone Handsets A novel triple‐band antenna that consists of a driven meander‐line element and two parasitic coupled elements has been presented in [11]. The geometrical configuration, size, and proximity of the driven and parasitic elements help materialize the desired multiband operation. The complete antenna assembly is internal to the handset. The antenna can be tuned to operate either in the 824–894 MHz, 880–960 MHz, and 1850–1990 MHz bands or in the 824–894 MHz, 880–960 MHz, and 1710–1880 MHz bands. The concept described in the paper can also be used to achieve other triple or multiband operations. The size of the antenna is 50 mm X 10 mm X 6 mm (3 cm3) or less. The analysis of the antenna is conducted using a full‐wave method of ‐ 15 ‐
CHAPTER‐2
moments (MoM) software package called IE3D. The present analysis of the antenna does not contain the effect of the user’s head and hand on the antenna impedance and pattern characteristics.
2.4.2 Multiband Folded Planar Monopole Antenna for Mobile Handsets Another multiband handset antenna that can afford multiband applications in the mobile systems, including GSM (880–960 MHz), DCS (1720–1880 MHz), PCS (1850–1990 MHz), UMTS (1920 2170 MHz), and ISM bands (2400–2484 MHz) has been presented in [12]. The planar monopole antenna can be constructed into different shapes such as circle, square, trapezoidal, or pentagonal. Among these shapes, the square planar monopole is favorable for its consistent radiation pattern over the operation bandwidth. However, it has a large ground plane size and antenna height (h) (larger than one tenth of the lowest operating frequency), which make it unsuitable for using in mobile phones. Recently, the antenna is integrated with the ground plane of the circuit board of the mobile phone. However, the proposed configuration, with a shorted rectangular patch, covers only about 10% of the operation bandwidth. The design mainly consists of a folded rectangular planar monopole and an inverted L‐shape ground plane to meet the needs for multiband operation and antenna size reduction. Furthermore, the design has many advantages for mobile phone applications, such as low cost, simple structure, compact size, very wide bandwidth, acceptable radiation efficiency, and omni‐directional radiation pattern.
2.4.3 A LowProfile Planar Monopole Antenna for Multiband Operation of Mobile Handsets Another novel planar monopole antenna design with a very low profile antenna (height less than 0.04 times the operating wavelength in the free space) ‐ 16 ‐
CHAPTER‐2
(the total antenna height is only 12 mm for operating at the 900‐MHz band) has been presented in [13]. The proposed antenna, 12 mm in height and 30 mm in width has been constructed, and the obtained bandwidths cover the 900‐MHz band global system for mobile communication (GSM), 1800‐MHz‐band digital communication system (DCS), 1900‐MHz‐band personal communication system (PCS), and 2050‐MHz‐band universal mobile telecommunication system (UMTS).
2.4.4 Design of an Internal QuadBand Antenna for Mobile Phones The antenna presented in [14], combines several techniques applied simultaneously which are necessary to reduce the size of these antennas while maintaining good multiband/wideband performance. The main resonator is a dual‐band PIFA antenna tuned to operate at center frequencies of 935 MHz and 1930 MHz. The introduction of a slot into this element allows a frequency decrease of its fundamental resonance while the use of an end positioned capacitive load allows its higher order modes to be decreased in frequency. The addition of three quarter‐wavelength parasitic elements is used here to create new resonances, and thus enlarge both lower and upper impedance bandwidth. These new resonances are tuned thanks to a lengthening by capacitive loads. This antenna covers the GSM standard (Global System for Mobile communications, 880–960 MHz) with a VSWR (Voltage Standing Wave Ratio) better than 2.5 and also the DCS (Digital Communication System, 1710–1880 MHz), PCS (Personal Communication Services, 1850–1990 MHz) and UMTS (Universal Mobile Telecommunications System, 1920–2170 MHz) standards with a VSWR less than or equal to 2.
‐ 17 ‐
CHAPTER‐2
2.4.5 Compact Internal Multiband Antenna for Mobile Phone and WLAN Standards The antenna presented in [15], is based on the quad‐band structure, and another technique is applied here to achieve the tuning of its higher order resonances in the WLAN band. The resulting structure is a well matched antenna in the GSM and the 2 GHz bands. Three quarter wavelength type, parasitic shorted patches are then added to widen these bandwidths. Each one is connected to the ground plane by metallic strips and located near the main patch in order to be efficiently electromagnetically coupled. A meticulous simulated parametric study was conducted on each patch by independently changing their physical parameters in order to identify and control their higher‐order modes around 5 GHz. It was found that the tuning and matching process of the resonances of all the parasitic led to only small modifications.
2.4.6 Multiband Internal Antenna for Mobile Phones A new internal antenna for Multiband cell phones comprise a U‐shaped elongated flat conductor featuring a closed meandered slot, a ground and a feed leg has been presented in [16]. A novel antenna structure for multiband mobile phones is featuring the folded inverted conformal antenna (FICA) as the antenna component. The FICA placement on the board and its feeding mechanisms are similar to those used currently for the great majority of handsets with internal planar inverted F‐antenna (PIFA) components. Whereas multiband PIFAs exhibit two resonant modes, which operate by sharing the available antenna volume, the FICA structure is synthesized in order to sustain three resonant modes that reuse the volume. The implementation of volume reuse allows spreading of the reactive electromagnetic energy associated with each resonant mode across the entire
‐ 18 ‐
CHAPTER‐2
antenna volume. Consequently the FICA modes exhibit a wider fractional bandwidth than the corresponding PIFA modes. A dual‐band PIFA component, when coupled with the handset circuit board, exhibits one resonance in the low cellular band 900 MHz, and one in the high band 1800 MHz. The FICA exhibits two resonances in those bands, plus an additional resonant mode that can be typically tuned to extend the higher cellular band coverage.
2.4.7 Conformal Shaped PIFAs for Mobile Communication Applications Radiators of two different configurations are considered in [17] and they are (a) Semi‐circular shaped radiator for GPS bands, and (b) Embedded PIFAs having the contour of a back‐housing of a typical cellular handset and exhibiting cellular dual and tri band performance. While conventional Micro strip antenna designs are based on half‐wavelength of operation, the PIFA designs invoke the quarter‐wavelength operation. The quarter wavelength of PIFA operation is due to the connection of the radiating element to the ground plane through a shorting strip or pin. This paper extends the scope of using a single feed for dual band semi circular PIFA design and the advantages of the proposed design. This paper also proposes embedded PIFAs with radiators conforming to the contour of the back‐housing of a typical cellular handset. The proposed embedded PIFA allows its formation as an integral part of the back housing. The radiating element of the PIFA conforming to the contour of the device also enables the optimum utilization of the available volume marked for the internal antenna.
‐ 19 ‐
CHAPTER‐2
2.4.8 New Compact SixBand Internal Antenna This paper [18] presents a novel compact six‐band internal antenna for mobile handsets covering the GSM900, GPS1570, DCS1800, PCS1900, WCDMA2000, and ISM2450 bands. The proposed antenna consists of two layer patches and a folded stub. The two patches share a common shorting strip, while the folded stub is not grounded. The antenna was realized within a volume of 8 X 17 X36 mm3.
2.4.9 Intelligent Quadrifilar Helix Antenna The paper [19] introduces the concept of the intelligent quadrifilar helix antenna (I‐QHA) as an antenna for handled mobile terminals. The potential advantages of using the I‐QHA in both terrestrial and satellite mobile communications are presented. The I‐QHA may be used as a multiband or multimode antenna, allowing a handset to operate in different frequencies bands and in both terrestrial and satellite communications environment. The adaptive matching component of the I‐QHA not only matches the antenna for different frequency bands, hut counters the detuning effects caused by the user.
‐ 20 ‐
Chapter2 Literature review 2. 2.1
Mobile Communication Evolution and Multiband Antennas Introduction The literature review shows some descriptions of the low profile antenna
especially about the multiband frequencies that they can operate at GSM900, DCS1800, PCS1900, and UMTS2000.It also study the performance of them in terms of input impedance, field patterns and gain. A number of papers explaining the different types of multiband antennas for multiple frequencies are presented here.
2.2 The Evolution of Mobile Telephone Systems Cellular is one of the fastest growing and most demanding telecommunications applications. Today, it represents a continuously increasing percentage of all new telephone subscriptions around the world. Over the last 12 years, the telecommunication/ICT sector has undergone major changes. With high growth in the mobile sector, mobile penetration rates stood at more than 40 percent at the end of 2006. ITU data suggest that the number of mobile cellular subscribers surpassed the 3 billion mark in August 2007. At current growth rates, global mobile penetration is expected to reach 50 percent by early 2008. Despite major differences between the developed and the developing world, mobile services have been critical in enhancing access to telecommunications in many developing regions and rural areas, where fixed lines remain limited or non‐ existing [51]. The concept of cellular service is the use of low‐power transmitters where frequencies can be reused within a geographic area.
‐ 14 ‐
CHAPTER‐2
2.3 Historical Review The idea of cell‐based mobile radio service was formulated in the United States at Bell Labs in the early 1970s. However, the Nordic countries were the first to introduce cellular services for commercial use with the introduction of the Nordic Mobile Telephone (NMT) in 1981. Cellular systems began in the United States with the release of the advanced mobile phone service (AMPS) system in 1983. The AMPS standard was adopted by Asia, Latin America, and Oceanic countries, creating the largest potential market in the world for cellular. In the early 1980s, most mobile telephone systems were analog rather than digital, like today's newer systems. One challenge facing analog systems was the inability to handle the growing capacity needs in a cost‐efficient manner. As a result, digital technology was welcomed. The advantages of digital systems over analog systems include ease of signaling, lower levels of interference, integration of transmission and switching, and increased ability to meet capacity demands.
2.4 Different Designs Available on Literature: 2.4.1 Design of a Multiband Internal Antenna for Third Generation Mobile Phone Handsets A novel triple‐band antenna that consists of a driven meander‐line element and two parasitic coupled elements has been presented in [11]. The geometrical configuration, size, and proximity of the driven and parasitic elements help materialize the desired multiband operation. The complete antenna assembly is internal to the handset. The antenna can be tuned to operate either in the 824–894 MHz, 880–960 MHz, and 1850–1990 MHz bands or in the 824–894 MHz, 880–960 MHz, and 1710–1880 MHz bands. The concept described in the paper can also be used to achieve other triple or multiband operations. The size of the antenna is 50 mm X 10 mm X 6 mm (3 cm3) or less. The analysis of the antenna is conducted using a full‐wave method of ‐ 15 ‐
CHAPTER‐2
moments (MoM) software package called IE3D. The present analysis of the antenna does not contain the effect of the user’s head and hand on the antenna impedance and pattern characteristics.
2.4.2 Multiband Folded Planar Monopole Antenna for Mobile Handsets Another multiband handset antenna that can afford multiband applications in the mobile systems, including GSM (880–960 MHz), DCS (1720–1880 MHz), PCS (1850–1990 MHz), UMTS (1920 2170 MHz), and ISM bands (2400–2484 MHz) has been presented in [12]. The planar monopole antenna can be constructed into different shapes such as circle, square, trapezoidal, or pentagonal. Among these shapes, the square planar monopole is favorable for its consistent radiation pattern over the operation bandwidth. However, it has a large ground plane size and antenna height (h) (larger than one tenth of the lowest operating frequency), which make it unsuitable for using in mobile phones. Recently, the antenna is integrated with the ground plane of the circuit board of the mobile phone. However, the proposed configuration, with a shorted rectangular patch, covers only about 10% of the operation bandwidth. The design mainly consists of a folded rectangular planar monopole and an inverted L‐shape ground plane to meet the needs for multiband operation and antenna size reduction. Furthermore, the design has many advantages for mobile phone applications, such as low cost, simple structure, compact size, very wide bandwidth, acceptable radiation efficiency, and omni‐directional radiation pattern.
2.4.3 A LowProfile Planar Monopole Antenna for Multiband Operation of Mobile Handsets Another novel planar monopole antenna design with a very low profile antenna (height less than 0.04 times the operating wavelength in the free space) ‐ 16 ‐
CHAPTER‐2
(the total antenna height is only 12 mm for operating at the 900‐MHz band) has been presented in [13]. The proposed antenna, 12 mm in height and 30 mm in width has been constructed, and the obtained bandwidths cover the 900‐MHz band global system for mobile communication (GSM), 1800‐MHz‐band digital communication system (DCS), 1900‐MHz‐band personal communication system (PCS), and 2050‐MHz‐band universal mobile telecommunication system (UMTS).
2.4.4 Design of an Internal QuadBand Antenna for Mobile Phones The antenna presented in [14], combines several techniques applied simultaneously which are necessary to reduce the size of these antennas while maintaining good multiband/wideband performance. The main resonator is a dual‐band PIFA antenna tuned to operate at center frequencies of 935 MHz and 1930 MHz. The introduction of a slot into this element allows a frequency decrease of its fundamental resonance while the use of an end positioned capacitive load allows its higher order modes to be decreased in frequency. The addition of three quarter‐wavelength parasitic elements is used here to create new resonances, and thus enlarge both lower and upper impedance bandwidth. These new resonances are tuned thanks to a lengthening by capacitive loads. This antenna covers the GSM standard (Global System for Mobile communications, 880–960 MHz) with a VSWR (Voltage Standing Wave Ratio) better than 2.5 and also the DCS (Digital Communication System, 1710–1880 MHz), PCS (Personal Communication Services, 1850–1990 MHz) and UMTS (Universal Mobile Telecommunications System, 1920–2170 MHz) standards with a VSWR less than or equal to 2.
‐ 17 ‐
CHAPTER‐2
2.4.5 Compact Internal Multiband Antenna for Mobile Phone and WLAN Standards The antenna presented in [15], is based on the quad‐band structure, and another technique is applied here to achieve the tuning of its higher order resonances in the WLAN band. The resulting structure is a well matched antenna in the GSM and the 2 GHz bands. Three quarter wavelength type, parasitic shorted patches are then added to widen these bandwidths. Each one is connected to the ground plane by metallic strips and located near the main patch in order to be efficiently electromagnetically coupled. A meticulous simulated parametric study was conducted on each patch by independently changing their physical parameters in order to identify and control their higher‐order modes around 5 GHz. It was found that the tuning and matching process of the resonances of all the parasitic led to only small modifications.
2.4.6 Multiband Internal Antenna for Mobile Phones A new internal antenna for Multiband cell phones comprise a U‐shaped elongated flat conductor featuring a closed meandered slot, a ground and a feed leg has been presented in [16]. A novel antenna structure for multiband mobile phones is featuring the folded inverted conformal antenna (FICA) as the antenna component. The FICA placement on the board and its feeding mechanisms are similar to those used currently for the great majority of handsets with internal planar inverted F‐antenna (PIFA) components. Whereas multiband PIFAs exhibit two resonant modes, which operate by sharing the available antenna volume, the FICA structure is synthesized in order to sustain three resonant modes that reuse the volume. The implementation of volume reuse allows spreading of the reactive electromagnetic energy associated with each resonant mode across the entire
‐ 18 ‐
CHAPTER‐2
antenna volume. Consequently the FICA modes exhibit a wider fractional bandwidth than the corresponding PIFA modes. A dual‐band PIFA component, when coupled with the handset circuit board, exhibits one resonance in the low cellular band 900 MHz, and one in the high band 1800 MHz. The FICA exhibits two resonances in those bands, plus an additional resonant mode that can be typically tuned to extend the higher cellular band coverage.
2.4.7 Conformal Shaped PIFAs for Mobile Communication Applications Radiators of two different configurations are considered in [17] and they are (a) Semi‐circular shaped radiator for GPS bands, and (b) Embedded PIFAs having the contour of a back‐housing of a typical cellular handset and exhibiting cellular dual and tri band performance. While conventional Micro strip antenna designs are based on half‐wavelength of operation, the PIFA designs invoke the quarter‐wavelength operation. The quarter wavelength of PIFA operation is due to the connection of the radiating element to the ground plane through a shorting strip or pin. This paper extends the scope of using a single feed for dual band semi circular PIFA design and the advantages of the proposed design. This paper also proposes embedded PIFAs with radiators conforming to the contour of the back‐housing of a typical cellular handset. The proposed embedded PIFA allows its formation as an integral part of the back housing. The radiating element of the PIFA conforming to the contour of the device also enables the optimum utilization of the available volume marked for the internal antenna.
‐ 19 ‐
CHAPTER‐2
2.4.8 New Compact SixBand Internal Antenna This paper [18] presents a novel compact six‐band internal antenna for mobile handsets covering the GSM900, GPS1570, DCS1800, PCS1900, WCDMA2000, and ISM2450 bands. The proposed antenna consists of two layer patches and a folded stub. The two patches share a common shorting strip, while the folded stub is not grounded. The antenna was realized within a volume of 8 X 17 X36 mm3.
2.4.9 Intelligent Quadrifilar Helix Antenna The paper [19] introduces the concept of the intelligent quadrifilar helix antenna (I‐QHA) as an antenna for handled mobile terminals. The potential advantages of using the I‐QHA in both terrestrial and satellite mobile communications are presented. The I‐QHA may be used as a multiband or multimode antenna, allowing a handset to operate in different frequencies bands and in both terrestrial and satellite communications environment. The adaptive matching component of the I‐QHA not only matches the antenna for different frequency bands, hut counters the detuning effects caused by the user.
‐ 20 ‐
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