Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1609021
M. Hosseini, A. Pirhadi, M. Hakkak
In this paper, an angularly stable Artificial Magnetic Conductor (AMC) or High-Impedance Surface (HIS) is proposed. The structure is made of the well know Jerusalem Cross Frequency Selective Surface (JC-FSS) placed at the interface of a metal-backed dielectric slab. The paper begins by investigating the properties of a structure optimized in a prior work. Innovatively, this structure is corrected and changed, and the resultant structure is optimized not completely based on time consuming optimization methods, but by utilizing the theoretical clues presented in another work for the same structure. Taking these strategies, just by a simple optimization procedure and some parametric studies, such a structure is obtained that shows better angular stability compared to the initial structure, while having acceptable bandwidth and compact size. Periodic method of moments (PMM) is used to analyze and study the proposed planar periodic structure. Index Terms—Artificial magnetic conductor (AMC), high-impedance surface (HIS), perfect magnetic conductor (PMC), electromagnetic band gap (EBG) surface, frequency selective surface (FSS)
{"title":"Design of an AMC with Little Sensitivity to Angle of Incidence Using an Optimized Jerusalem Cross FSS","authors":"M. Hosseini, A. Pirhadi, M. Hakkak","doi":"10.1109/IWAT.2006.1609021","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1609021","url":null,"abstract":"In this paper, an angularly stable Artificial Magnetic Conductor (AMC) or High-Impedance Surface (HIS) is proposed. The structure is made of the well know Jerusalem Cross Frequency Selective Surface (JC-FSS) placed at the interface of a metal-backed dielectric slab. The paper begins by investigating the properties of a structure optimized in a prior work. Innovatively, this structure is corrected and changed, and the resultant structure is optimized not completely based on time consuming optimization methods, but by utilizing the theoretical clues presented in another work for the same structure. Taking these strategies, just by a simple optimization procedure and some parametric studies, such a structure is obtained that shows better angular stability compared to the initial structure, while having acceptable bandwidth and compact size. Periodic method of moments (PMM) is used to analyze and study the proposed planar periodic structure. Index Terms—Artificial magnetic conductor (AMC), high-impedance surface (HIS), perfect magnetic conductor (PMC), electromagnetic band gap (EBG) surface, frequency selective surface (FSS)","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123079296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1608978
H.S. Choi, S.H. Kim, K. Oh, J. Jang
Wireless local area network (WLAN) is one of the rapidly growing applications in wireless communications. Antennas for portable WLAN devices require wideband, low profile, and compact design [1]. Dual-band antennas are also attractive because they eliminate the need of separate antennas by allowing operations at multiple frequency bands specified in IEEE standards 802.11b/g (2.400~2.484 GHz) and 802.11a (5.150~5.850 GHz) [2]. Coplanar waveguide (CPW)-fed antennas have been investigated for WLAN applications because of their advantages such as wide band characteristics, dualor multi-band operation, simple structures with only one metal layer, and easy integration on the circuit board along with integrated circuit components. However, CPW-fed antennas reported in the literatures so far exhibited insufficient bandwidth at 5 GHz band [3-4] or suffered from large size although they satisfied bandwidth requirements of WLAN [5-6]. In this paper, CPW-fed monopole antenna with double inverted-L strips was designed for dual-band WLAN applications. The fabricated antenna has an ultra-compact size (15 mm × 14 mm) that includes the size of ground planes. The measured characteristics exhibited wide bandwidths in both 2 and 5 GHz bands. Especially in 5 GHz band, the antenna demonstrated ultra-wide bandwidth covering from 4.76 to 6.48 GHz. Details of antenna design are described, and the simulated and measured antenna characteristics are compared and discussed.
{"title":"Ultra-compact CPW-fed Monopole Antenna with Double Inverted-L Strips for Dual-Band WLAN Applications","authors":"H.S. Choi, S.H. Kim, K. Oh, J. Jang","doi":"10.1109/IWAT.2006.1608978","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1608978","url":null,"abstract":"Wireless local area network (WLAN) is one of the rapidly growing applications in wireless communications. Antennas for portable WLAN devices require wideband, low profile, and compact design [1]. Dual-band antennas are also attractive because they eliminate the need of separate antennas by allowing operations at multiple frequency bands specified in IEEE standards 802.11b/g (2.400~2.484 GHz) and 802.11a (5.150~5.850 GHz) [2]. Coplanar waveguide (CPW)-fed antennas have been investigated for WLAN applications because of their advantages such as wide band characteristics, dualor multi-band operation, simple structures with only one metal layer, and easy integration on the circuit board along with integrated circuit components. However, CPW-fed antennas reported in the literatures so far exhibited insufficient bandwidth at 5 GHz band [3-4] or suffered from large size although they satisfied bandwidth requirements of WLAN [5-6]. In this paper, CPW-fed monopole antenna with double inverted-L strips was designed for dual-band WLAN applications. The fabricated antenna has an ultra-compact size (15 mm × 14 mm) that includes the size of ground planes. The measured characteristics exhibited wide bandwidths in both 2 and 5 GHz bands. Especially in 5 GHz band, the antenna demonstrated ultra-wide bandwidth covering from 4.76 to 6.48 GHz. Details of antenna design are described, and the simulated and measured antenna characteristics are compared and discussed.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115474442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1608995
K. Ito, K. Fujii
INTRODUCTION As cellular phones, personal digital assistants (PDAs), pocket video games, and other information and communication devices become smaller and more widespread, we have begun to adorn our bodies with these appliances and the opportunities to use these small computers have been increased in our everyday lives. We can say with fair certainty that miniaturization of these devices will evolve, and we will meet the ubiquitous computing society [1]. However, currently there is no method for these personal devices to exchange data directly. If these devices are wire-connected, it is clearly impractical because they easily become tangled, so some sort of short-range wireless technology is required. The concept for networking these personal devices has been proposed as Personal Area Networks (PANs) which use the human body as a transmission channel [2]. Although many studies have been made on the development of wearable devices using the human body as a transmission channel, little is known about the transmission mechanism of such devices in the physical layer [2]-[8]. Figs. 1 3 show a few examples of communication systems of the PANs [5]. When a user wearing the transmitter touches the electrode of the receiver, a transmission channel is formed using the human body. In this case, the receiver recognizes the user's ID and it can be personalized. The merit of this system is that the data is exchanged through daily natural actions, such as simply touching the receiver. This communication system uses the near field region of the electromagnetic wave generated by the device which is eventually coupled to the human body by electrodes. Hence, the structure of electrodes is one of the key issues for the transmission using human body. The difference of the transmission power caused by the electrode structure needs to be considered in detail.
{"title":"Development and Investigation of the Transmission Mechanism of the Wearable Devices Using the Human Body as a Transmission Channel","authors":"K. Ito, K. Fujii","doi":"10.1109/IWAT.2006.1608995","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1608995","url":null,"abstract":"INTRODUCTION As cellular phones, personal digital assistants (PDAs), pocket video games, and other information and communication devices become smaller and more widespread, we have begun to adorn our bodies with these appliances and the opportunities to use these small computers have been increased in our everyday lives. We can say with fair certainty that miniaturization of these devices will evolve, and we will meet the ubiquitous computing society [1]. However, currently there is no method for these personal devices to exchange data directly. If these devices are wire-connected, it is clearly impractical because they easily become tangled, so some sort of short-range wireless technology is required. The concept for networking these personal devices has been proposed as Personal Area Networks (PANs) which use the human body as a transmission channel [2]. Although many studies have been made on the development of wearable devices using the human body as a transmission channel, little is known about the transmission mechanism of such devices in the physical layer [2]-[8]. Figs. 1 3 show a few examples of communication systems of the PANs [5]. When a user wearing the transmitter touches the electrode of the receiver, a transmission channel is formed using the human body. In this case, the receiver recognizes the user's ID and it can be personalized. The merit of this system is that the data is exchanged through daily natural actions, such as simply touching the receiver. This communication system uses the near field region of the electromagnetic wave generated by the device which is eventually coupled to the human body by electrodes. Hence, the structure of electrodes is one of the key issues for the transmission using human body. The difference of the transmission power caused by the electrode structure needs to be considered in detail.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130723424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1608963
M. Abedin, M. Ali
A low-cost smaller unit-cell planar EBG structure operating at the lower GHz frequencies (below 6 GHz) is proposed. A numerical simulation model is developed to predict the reflection phase stopband of such structures. A highly directional dipole antenna placed on top of our proposed planar EBG structure with an overall height of 0.02λ is demonstrated.
{"title":"A Low Profile Dipole Antenna Backed by a Planar EBG Structure","authors":"M. Abedin, M. Ali","doi":"10.1109/IWAT.2006.1608963","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1608963","url":null,"abstract":"A low-cost smaller unit-cell planar EBG structure operating at the lower GHz frequencies (below 6 GHz) is proposed. A numerical simulation model is developed to predict the reflection phase stopband of such structures. A highly directional dipole antenna placed on top of our proposed planar EBG structure with an overall height of 0.02λ is demonstrated.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114954817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1609035
Taeyoung Yang, W. Davis, W. Stutzman
The ultra-wideband (UWB) technology is of current interest in both academics and industry. UWB provides a potential solution to the frequency shortage issue and offers a significant increase in data-throughput. In addition, the UWB technology can be used for realizing ubiquitous network environments [1, 2]. For antennas to support UWB communications, various planar, monopole-like UWB antennas have been proposed as shown in Fig. 1. The antennas include monopoles of rectangular shape (Fig 1a) [3-4], an inverted triangular form similar to the bow-tie dipole (Fig. 1b) [5], a triangular form (Fig. 1c) [6], a round disk (Fig. 1d) [7], elliptical disk (Fig. 1e) [8], a half-disk (Fig. 1f) [9], and inverted cone with holes (Fig.1g) [10]. The antennas are shown in monopole form, but they can also be configured as balanced antennas or used with small ground planes parallel to the antenna. Typically, the ratio of height-to-width of these antennas is in the range of 2 to 1. However, the footprint for some portable UWB applications, such as notebook computers, cell phones, and MP3 players, requires a higher ratio, making the width a more critical specification than height. To meet this need, several sample structures were constructed in a rolled form to create UWB antennas with a higher ratio. The bi-arm rolled monopole (Fig. 1h) is created by wrapping the rectangular monopole to achieve about a 5.3:1 height-to-width ratio [11] and showing a good impulse response with a fast decayed ringing. The monopole with a twist (Fig. 1i) is created by wrapping the half of a triangular monopole to obtain about a 2:1 ratio [12]. However, the metal patterns of both antennas are not located on the surface of the cylinder with fixed radius, which poses a challenge when printed on flexible printed circuit boards or on thin film for mass production. In this paper, we investigate a logarithmic tape helix with equiangular width of Fig. 2. The metal pattern is located on the surface of the cylinder with fixed radius. Some experimental and simulation results in both time and frequency domains are provided to characterized the test antenna. The return loss and link impulse response are compared with a fat monopole of the same size.
{"title":"Normal-mode, Logarithmic, Ultra-wideband Tape Helix","authors":"Taeyoung Yang, W. Davis, W. Stutzman","doi":"10.1109/IWAT.2006.1609035","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1609035","url":null,"abstract":"The ultra-wideband (UWB) technology is of current interest in both academics and industry. UWB provides a potential solution to the frequency shortage issue and offers a significant increase in data-throughput. In addition, the UWB technology can be used for realizing ubiquitous network environments [1, 2]. For antennas to support UWB communications, various planar, monopole-like UWB antennas have been proposed as shown in Fig. 1. The antennas include monopoles of rectangular shape (Fig 1a) [3-4], an inverted triangular form similar to the bow-tie dipole (Fig. 1b) [5], a triangular form (Fig. 1c) [6], a round disk (Fig. 1d) [7], elliptical disk (Fig. 1e) [8], a half-disk (Fig. 1f) [9], and inverted cone with holes (Fig.1g) [10]. The antennas are shown in monopole form, but they can also be configured as balanced antennas or used with small ground planes parallel to the antenna. Typically, the ratio of height-to-width of these antennas is in the range of 2 to 1. However, the footprint for some portable UWB applications, such as notebook computers, cell phones, and MP3 players, requires a higher ratio, making the width a more critical specification than height. To meet this need, several sample structures were constructed in a rolled form to create UWB antennas with a higher ratio. The bi-arm rolled monopole (Fig. 1h) is created by wrapping the rectangular monopole to achieve about a 5.3:1 height-to-width ratio [11] and showing a good impulse response with a fast decayed ringing. The monopole with a twist (Fig. 1i) is created by wrapping the half of a triangular monopole to obtain about a 2:1 ratio [12]. However, the metal patterns of both antennas are not located on the surface of the cylinder with fixed radius, which poses a challenge when printed on flexible printed circuit boards or on thin film for mass production. In this paper, we investigate a logarithmic tape helix with equiangular width of Fig. 2. The metal pattern is located on the surface of the cylinder with fixed radius. Some experimental and simulation results in both time and frequency domains are provided to characterized the test antenna. The return loss and link impulse response are compared with a fat monopole of the same size.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127721861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1609057
Jie Zhou, Jiejun Wang, Chao Huang, D. Xiao
This paper investigates the effect of fading correlation on symbol error rate (SER) performance of M-ray phase shift keying (MPSK) with maximal ratio combining (MRC) for a circular antenna array. The performance evaluation uses the known expression for the SER of MPSK in additive white Gaussian noise (AWGN) as the conditional probability, then averages it over the density function for the combined symbol signal-to-noise ratio (SNR). By investigating the SER Performance using the correlation matrix for circular antenna array, we prove that, for circular array, decrease in the radius and number of antennas is equivalent to decrease in signal to noise ratio and increase in SER.
{"title":"Effect of Spatial Fading Correlation on the SER Performance of MPSK with MRC for Circular Antenna Array","authors":"Jie Zhou, Jiejun Wang, Chao Huang, D. Xiao","doi":"10.1109/IWAT.2006.1609057","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1609057","url":null,"abstract":"This paper investigates the effect of fading correlation on symbol error rate (SER) performance of M-ray phase shift keying (MPSK) with maximal ratio combining (MRC) for a circular antenna array. The performance evaluation uses the known expression for the SER of MPSK in additive white Gaussian noise (AWGN) as the conditional probability, then averages it over the density function for the combined symbol signal-to-noise ratio (SNR). By investigating the SER Performance using the correlation matrix for circular antenna array, we prove that, for circular array, decrease in the radius and number of antennas is equivalent to decrease in signal to noise ratio and increase in SER.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127742081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1609044
Chunmin Lai, R. Rojas
{"title":"Generalized Transverse Resonance Method for Design and Analysis of Semiconductor Magnetoplasmon-Based Nonreciprocal Devices","authors":"Chunmin Lai, R. Rojas","doi":"10.1109/IWAT.2006.1609044","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1609044","url":null,"abstract":"","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"46 7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127361556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1609061
A. Lai, K. Leong, T. Itoh
The transmission line (TL) approach to composite right/left-handed (CRLH) metamaterials has led to various novel microwave devices [1]. In particular, the extraordinary properties of the CRLH metamaterial have been used to realize antennas not possible with conventional materials alone. The purpose of this paper is to review the CRLH metamaterial’s unique features which have been used to realize novel leaky-wave antennas, compact planar antennas, and infinite wavelength resonant antennas at the authors’ research laboratory.
{"title":"Composite Right/Left-Handed Metamaterial Antennas","authors":"A. Lai, K. Leong, T. Itoh","doi":"10.1109/IWAT.2006.1609061","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1609061","url":null,"abstract":"The transmission line (TL) approach to composite right/left-handed (CRLH) metamaterials has led to various novel microwave devices [1]. In particular, the extraordinary properties of the CRLH metamaterial have been used to realize antennas not possible with conventional materials alone. The purpose of this paper is to review the CRLH metamaterial’s unique features which have been used to realize novel leaky-wave antennas, compact planar antennas, and infinite wavelength resonant antennas at the authors’ research laboratory.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122382189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-03-06DOI: 10.1109/IWAT.2006.1609038
N. Ishii, M. Miyakawa
For measuring the radiation efficiency of the small antenna, the Wheeler method can be used because of its simplicity and accuracy [1]. It makes possible a wideband measurement of the radiation efficiency except resonant frequencies of its shielding. At these frequencies, dips of the radiation efficiency can be observed because the loss of the shielding is dominant over the loss of the antenna [2]. In the reflection method [3], the shielding is replaced by a straight waveguide and two sliding shorts so that the dips of the radiation efficiency can be observed as well as the Wheeler method for the same reason. To facilitate the mechanism by terms of simple expressions, we consider the waveguide and two shorts as a transmission line which is terminated by resistive loads in place of the shorts. That is, the loss of the shielding is expressed by the resistance at the terminations [4]. The transmission line model can predict not only the center frequency of the dip but also the frequency response of the estimated efficiency if the normalized resistance is well adjusted [4]. However, our previous paper assumes that the antenna be ideal. That is, when the S parameters of the corresponding two-port network are introduced, the relation of |S11| = |S22| = 0 and |S21| = |S12| = 1 is assumed. In this paper, the mechanism of the dips will be revealed in terms of the transmission line model with no assumption of the ideal antenna. According to our result, the estimated efficiency can be decomposed into the true antenna efficiency and the efficiency in the part of the waveguide and the shorts. The total estimated efficiency has possibility to have its dip in conjunction with the dip in the latter efficiency. This is the reason why the dips are observed in the total estimated efficiency. Of course, the antenna efficiency is independent of the dips in the latter efficiency. Moreover, this paper clarifies the fact that dips are observed when the center of the circle on the latter efficiency is extremely offset from the origin as well as its radius approaches to zero. This means that the value of the standing wave in the waveguide is null at the position of the antenna so that the loss of the shielding is dominant.
{"title":"Analysis on the Dips of the Radiation Efficiency in the Reflection Method Using the Transmission Line Model","authors":"N. Ishii, M. Miyakawa","doi":"10.1109/IWAT.2006.1609038","DOIUrl":"https://doi.org/10.1109/IWAT.2006.1609038","url":null,"abstract":"For measuring the radiation efficiency of the small antenna, the Wheeler method can be used because of its simplicity and accuracy [1]. It makes possible a wideband measurement of the radiation efficiency except resonant frequencies of its shielding. At these frequencies, dips of the radiation efficiency can be observed because the loss of the shielding is dominant over the loss of the antenna [2]. In the reflection method [3], the shielding is replaced by a straight waveguide and two sliding shorts so that the dips of the radiation efficiency can be observed as well as the Wheeler method for the same reason. To facilitate the mechanism by terms of simple expressions, we consider the waveguide and two shorts as a transmission line which is terminated by resistive loads in place of the shorts. That is, the loss of the shielding is expressed by the resistance at the terminations [4]. The transmission line model can predict not only the center frequency of the dip but also the frequency response of the estimated efficiency if the normalized resistance is well adjusted [4]. However, our previous paper assumes that the antenna be ideal. That is, when the S parameters of the corresponding two-port network are introduced, the relation of |S11| = |S22| = 0 and |S21| = |S12| = 1 is assumed. In this paper, the mechanism of the dips will be revealed in terms of the transmission line model with no assumption of the ideal antenna. According to our result, the estimated efficiency can be decomposed into the true antenna efficiency and the efficiency in the part of the waveguide and the shorts. The total estimated efficiency has possibility to have its dip in conjunction with the dip in the latter efficiency. This is the reason why the dips are observed in the total estimated efficiency. Of course, the antenna efficiency is independent of the dips in the latter efficiency. Moreover, this paper clarifies the fact that dips are observed when the center of the circle on the latter efficiency is extremely offset from the origin as well as its radius approaches to zero. This means that the value of the standing wave in the waveguide is null at the position of the antenna so that the loss of the shielding is dominant.","PeriodicalId":162557,"journal":{"name":"IEEE International Workshop on Antenna Technology Small Antennas and Novel Metamaterials, 2006.","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130450216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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