Showing papers on "Folded inverted conformal antenna published in 2007"
TL;DR: A wideband E-shaped microstrip patch antenna has been designed for high-speed wireless local area networks (IEEE 802.11a) and other wireless communication systems covering the 5.15-5.825 GHz frequency band.
Abstract: A wideband E-shaped microstrip patch antenna has been designed for high-speed wireless local area networks (IEEE 802.11a standard) and other wireless communication systems covering the 5.15-5.825 GHz frequency band. Two parallel slots are incorporated to perturb the surface current path, introducing local inductive effect that is responsible for the excitation of the second resonant mode. The length of the center arm can be trimmed to tune the frequency of the second resonant mode without affecting the fundamental resonant mode. A comprehensive parametric study has been carried out to understand the effects of various dimensional parameters and to optimize the performance of the antenna. A substrate of low dielectric constant is selected to obtain a compact radiating structure that meets the demanding bandwidth specification. The reflection coefficient at the input of the optimized E-shaped microstrip patch antenna is below -10 dB over the entire frequency band. The measurement results are in excellent agreement with the HFSS simulation results.
300 citations
TL;DR: In this article, a new internal multiband mobile phone antenna formed by two printed monopole slots of different lengths cut at the edge of the system ground plane of the mobile phone is presented.
Abstract: A new internal multiband mobile phone antenna formed by two printed monopole slots of different lengths cut at the edge of the system ground plane of the mobile phone is presented. The antenna can generate two wide bands centered at about 900 and 2100 MHz to cover the GSM850/GSM900/DCS/PCS/UMTS bands and the 2.4-GHz WLAN band. Further, the antenna has a simple planar structure and occupies a small area of only. It is also promising to bend the antenna into an L shape to reduce its volume occupied inside the mobile phone. Good radiation characteristics are obtained over the two wide operating bands.
227 citations
TL;DR: The results confirm good performance of the two multiband reconfigurable antenna designs investigated, which can cover GSM, DCS, PCS, UMTS, Bluetooth, and 2.4 GHz wireless LAN.
Abstract: New designs for compact reconfigurable antennas are introduced for mobile communication devices. The uniqueness of the antenna designs are that they allow various groups of their operating frequency bands to be selected electronically. In particular, each group of frequency bands, or mode, can be made to serve several different communication systems simultaneously. These systems may include various combinations of GSM, DCS, PCS, UMTS, Bluetooth, and wireless local-area network (LAN). Therefore, by electronically selecting different antenna modes, a variety of communication systems can be conveniently served by only one antenna. One advantage is that through the different operational modes, the total antenna volume can be reused, and therefore the overall antenna can be made compact. In these designs, the selection of the different modes is achieved by either i) switching different feeding locations of the antenna (switched feed) or ii) switching or breaking of the antenna's connection to the ground (switched ground). This paper demonstrates these two designs. For the first design of switched feed, it can support GSM, DCS, PCS, and UMTS. In the second design, the antenna makes use of a switched-ground technique, which can cover GSM, DCS, PCS, UMTS, Bluetooth, and 2.4 GHz wireless LAN. The designs are investigated when ideal switches and also various realistic active switches based on PIN diodes, GaAs field effect transistor, and MEMs configurations. The designs are verified through both numerical simulations and measurement of an experimental prototype. The results confirm good performance of the two multiband reconfigurable antenna designs.
222 citations
TL;DR: In this paper, a coplanar waveguide fed quasi-Yagi antenna with broad bandwidth is presented, where the antenna is realized on a high dielectric constant substrate and compatible with microstrip circuitry and active devices.
Abstract: In this letter, we present a novel coplanar waveguide fed quasi-Yagi antenna with broad bandwidth. The uniqueness of this design is due to its simple feed selection and despite this, its achievable bandwidth. The 10 dB return loss bandwidth of the antenna is 44% covering X-band. The antenna is realized on a high dielectric constant substrate and is compatible with microstrip circuitry and active devices. The gain of the antenna is 7.4 dBi, the front-to-back ratio is 15 dB and the nominal efficiency of the radiator is 95%.
165 citations
TL;DR: In this article, a slot-loaded Yagi patch antenna with dual-band and pattern reconfigurable characteristics is presented, where the beam can scan in the E-plane by switching the modes of the antenna by changing the states of the switches installed in the slots etched on the parasitic patches.
Abstract: This letter presents a slot-loaded Yagi patch antenna with dual-band and pattern reconfigurable characteristics. The beam can scan in the E-plane by switching the modes of the antenna, which is implemented by changing the states of the switches installed in the slots etched on the parasitic patches. Different modes of the antenna have different radiation patterns and operating frequency bands. There are three modes having a common band of 9.15-9.45 GHz and their beams direct to -7deg, +33.5deg, and -40deg in the E-plane. Two among three modes also have another common frequency band around 10.3 GHz and the main beams direct to +58.5deg and -62.5deg, respectively. The third mode also has another frequency band around 10.85 GHz and has a dual-beam pattern. Simulated and measured results are given and they agree well with each other. The antenna can be used in radar, satellite communications, etc
159 citations
Patent•
08 May 2007TL;DR: In this article, an antenna (1) comprises a number of antenna units (10, 20, 30), each comprising a lens (11, 12, 13) and any array (21, 22, 23) of beam ports (32).
Abstract: An antenna (1) comprises a number of antenna units (10, 20, 30), each comprising a lens (11, 12, 13) and any array (21, 22, 23) of beam ports (32). The antenna units (10, 20, 30) are arranged in a stack, and are configured to transmit or receive signals from the same field-of-view. Each unit (10, 20, 30) is configured to operate in a different frequency band, with the lenses (11, 12, 13) being configured such that an approximately constant beam shape is maintained across the entire operating bandwidth of the antenna (1).
130 citations
TL;DR: In this paper, a coplanar strip fed monopole antenna for multiband applications is presented, which exhibits three resonances around 1.8, 2.4, and 5.6 GHz covering the DCS/PCS/UMTS/IEEE 802.11a/HIPERLAN2 bands.
Abstract: A compact asymmetric coplanar strip fed monopole antenna for multiband applications is presented. The antenna exhibits three resonances around 1.8, 2.4, and 5.6 GHz covering the DCS/PCS/UMTS/IEEE 802.11b/g/IEEE802.11a/HIPERLAN2 bands. The multiband characteristic of the antenna is due to the various meandered current paths excited in the radiating structure. The antenna has an overall dimension of only 2830 when printed on a substrate of dielectric constant 4.4. The uniplanar design, simple feeding technique and compactness make it easy for the integration of the antenna into circuit boards. Details of the antenna design, experimental and simulated results are presented and discussed.
119 citations
TL;DR: In this paper, a broadband differential-fed patch antenna (DFPA) with good radiation pattern is proposed and studied, where a folded plate pair is employed as the differential feeding scheme, which subtly acts as an impedance matching media for two radiation modes of the antenna, conducing to the wide impedance bandwidth.
Abstract: A broadband differential-fed patch antenna (DFPA) with good radiation pattern is proposed and studied. Unlike conventional DFPAs, the proposed antenna employs a folded plate pair as the differential feeding scheme. The devised feeding approach subtly acts as an impedance matching media for two radiation modes of the antenna, conducing to the wide impedance bandwidth. The conceived bandwidth enhancement technique demonstrates an impedance bandwidth (SWR les2) of up to 74% which outperforms conventional broadband patch antennas of more than 20%. Meanwhile, by using a differentially-driven signal along with the introduced feeding scheme, symmetric radiation patterns, low cross-polarization levels and stable radiation patterns are realized within the band. More importantly, the antenna has a stable gain at 8.5 dBi within a wide frequency range, demonstrating the high stability of the radiation characteristics for the two radiation modes. Analysis and parametric studies of the proposed feeding structure are provided.
83 citations
TL;DR: In this paper, the performance of a dual-band PIFA and a dual band helical antenna designed for operating in GSM900 and DCS1800 frequency bands is investigated in free space as well as in the presence of head and hand.
Abstract: Helical antenna and planar inverted-F antenna (PIFA) are two commonly used handset antennas. This paper presents a comprehensive study on the performance of a dual band PIFA and a dual band helical antenna designed for operating in GSM900 and DCS1800 frequency bands. Radiation patterns and VSWR of these antennas are computed in free space as well as in the presence of head and hand. The specific absorption rate (SAR) of the helical antenna is calculated and compared with that of the PIFA handset antenna. The peak average SAR in the head is compared with SAR limits in the safety standards and so the maximum radiation power of each antenna is determined. In addition, radiation efficiencies of these handset antennas are computed in the presence of head and hand. All numerical simulations are performed using the Ansoft HFSS software. Numerical simulations results are in good agreement with published measurement results.
79 citations
Patent•
12 Apr 2007
TL;DR: In this article, a multiband coupling network is proposed to selectively couple the multiband communication device (120) and multiband planar antenna apparatus (110) in order to constrain the directional radiatio pattern.
Abstract: A system (100) and method for a wireless link to a remote receiver includes a multiband communication device (120) for generating R and a multiband planar antenna apparatus (110) for transmitting the RF. The multiband planar antenna apparatus (110) includes selectable antenna elements, each of which has gain and a directional radiation pattern. Switching different antenna elements results in configurable radiation pattern. One or more directors and/or one or more reflectors may be included to constrict the directional radiatio pattern. A multiband coupling network selectively couples the multiband communication device (120) and the multiband planar antenna apparatus (110).
78 citations
TL;DR: In this article, the behavior of a matched electrically small antenna that exhibits two impedance resonances within its defined voltage standing wave ratio (VSWR) bandwidth was examined, and the exact quality factor (Q), computed indirectly from the antenna's input reactance and far field, was compared to twice the inverse of the matched half-power VSWR bandwidth.
Abstract: We examine the behavior of a matched electrically small antenna that exhibits two impedance resonances within its defined voltage standing wave ratio (VSWR) bandwidth. The exact quality factor (Q), computed indirectly from the antenna's input reactance and far field, is compared to twice the inverse of the matched half-power VSWR bandwidth (Q BW) and to an approximate quality factor (Qz) determined from the frequency derivative of the antenna's input impedance. The well-established approximate equalities Q ap Q BW ap Q z for antennas exhibiting an isolated single impedance resonance within their operating band are shown to become highly inaccurate for an electrically small antenna exhibiting two closely spaced impedance resonances.
TL;DR: In this article, a planar antenna consisting of an S-strip and a T-strip which are separately printed on the two sides of a thin substrate is developed for global positioning system (GPS), DCS-1800, IMT-2000, and WLAN handsets.
Abstract: A compact broadband planar antenna is developed for global positioning system (GPS), DCS-1800, IMT-2000, and WLAN handsets. The planar antenna consists of an S-strip and a T-strip which are separately printed on the two sides of a thin substrate (no via process is involved in the fabrication). The antenna size is only 18 mm$\,\times\,$7.2 mm $\,\times\,$0.254 mm which is more compact than previously published antenna configurations. The bandwidth of the planar antenna is enhanced by the mutual coupling between the S-strip and the T-strip. It has been demonstrated by simulation and experiment that the compact planar antenna can achieve a bandwidth of more than 50% for return loss $
TL;DR: In this paper, a dual-band enhanced-bandwidth microstrip antenna with a frequency separation of f2/f1=1.37 was presented, where a rectangular patch antenna was reactively loaded with a stub placed along one of the radiating edges.
Abstract: A dual-band enhanced-bandwidth microstrip antenna is presented with a frequency separation of f2/f1=1.37. In order to achieve the dual-frequency operation, a rectangular patch antenna is reactively loaded with a stub placed along one of the radiating edges. Then, the bandwidth is enhanced using a stacked parasitic technique, whereas the matching and radiation characteristics are kept constant along each band and similar at two bands.
TL;DR: In this paper, the design of a microstrip bi-Yagi and microstrip quad Yagi array antenna is presented, which can achieve high gain and a high front-to-back (F/B) ratio in comparison to the conventional microstrip Yagi structure first proposed by Huang in 1989.
Abstract: In this letter, the design of a microstrip bi-Yagi and microstrip quad-Yagi array antenna is presented. These designs are a derivative of the original microstrip Yagi antenna array and can achieve a high gain and a high front-to-back (F/B) ratio in comparison to the conventional microstrip Yagi structure first proposed by Huang in 1989. The proposed Bi-Yagi and quad-Yagi antenna arrays can also achieve a higher gain (3-6 dB) than the conventional microstrip Yagi array. Simple fabrication techniques can be used with these designs due to the placement of the feeding network on the same layer with the antenna elements. Furthermore, simulations and measurements demonstrate with very good agreement that the proposed arrays can achieve a gain as high as 15.6 dBi (compared to a gain of 10.7 dBi that is achieved by the microstrip Yagi antenna array) while maintaining an F/B ratio that is relatively high.
TL;DR: In this paper, an annular-ring slot antenna that is suitable for the 2.4/5 GHz dual-band operations was miniaturized by embedding in the center patch of the antenna a pair of slots to excite three resonant modes.
Abstract: This letter aims at miniaturizing an annular-ring slot antenna that is suitable for the 2.4/5-GHz dual-band operations. The miniaturization purpose was achieved by embedding in the center patch of the antenna a pair of slots to excite three resonant modes. The resonant band of the first excited resonant mode was lowered from that of the unperturbed annular-ring slot antenna, whereas those of the second and third excited resonant modes were combined to form a wide upper operating band by appropriately adjusting the dimensions of the embedded slots. The proposed antenna proves to have very similar copolarization radiation patterns in its two operating bands and have enough antenna gains for practical applications.
TL;DR: In this paper, a new design of a broadband 1-18 GHz double-horn antenna with redesigned feeding section is presented, and several modifications are made in the structure of a conventional double ridged g...
Abstract: A new design of a broadband 1–18 GHz double ridged guide horn antenna with redesigned feeding section is presented. Several modifications are made in the structure of a conventional double ridged g...
TL;DR: In this paper, a dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described, which can be used to double the operational bandwidth without significant size or performance penalties.
Abstract: A dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described. It is shown that co-design of the antenna and front-end can be used to double the operational bandwidth, without significant size or performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexing, which results in improved overall efficiency
TL;DR: In this paper, the integration of an on-chip folded dipole antenna with a monolithic 24 GHz receiver manufactured in a 0.8mum SiGe HBT process is presented.
Abstract: The integration of an on-chip folded dipole antenna with a monolithic 24-GHz receiver manufactured in a 0.8-mum SiGe HBT process is presented. A high-resistivity silicon substrate (1000 Omega ldr cm) is used for the implemented circuit to improve the efficiency of the integrated antenna. Crosstalk between the antenna and spiral inductors is analyzed and isolation techniques are described. The receiver, including the receive and an optional transmit antenna, requires a chip area of 4.5 mm2 and provides 30-dB conversion gain at 24 GHz with a power consumption of 960 mW.
TL;DR: In this article, a novel contactless, differential feeding technique suitable for integrated active antenna design is demonstrated, which utilizes an odd mode signal to generate fringing fields on either side of a microstrip gap under the antenna, allowing electromagnetic energy to be efficiently coupled from the transmission lines to the radiating antenna.
Abstract: A novel contact-less, differential feeding technique suitable for integrated active antenna design is demonstrated. This technique utilizes an odd mode signal to generate fringing fields on either side of a microstrip gap under the antenna. This allows electromagnetic energy to be efficiently coupled from the transmission lines to the radiating antenna. In a balanced integrated antenna amplifier configuration, the proposed non-contact feeding method removes the need for any balun or power combining network. Hence in theory, a compact RF front-end design with lower losses can be realized. This feeding method has been successfully applied to the design of simple passive microstrip patch antennas and active integrated antennas (AIA). Simulated and measured results are also included to validate the proposed feeding concept and antenna designs. The performance of the proposed differential feeding technique on a simple microstrip patch antenna has been systematically studied. The study suggests that the proposed proximity method is broadband in nature, allowing antennas operating at different resonant frequencies to be swapped without the need to change the feed dimensions and without degrading the matching performance
TL;DR: In this paper, approximate equations to calculate the resonant length of various compact rectangular microstrip antennas like, C-shaped, H-shaped and rectangular ring microstrip antenna, are proposed.
Abstract: The approximate equations to calculate the resonant length of various compact rectangular microstrip antennas like, C-shaped, H-shaped, and rectangular ring microstrip antenna, are proposed. The error in the calculated resonance frequency is <5%. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 498–501, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22161
TL;DR: In this article, a probe fed stacked microstrip patch antenna for operation in dual polarisation mode is proposed, where a slot loaded lower patch is presented to improve isolation between the two polarisation ports.
Abstract: A probe fed stacked microstrip patch antenna for operation in dual polarisation mode is proposed. A slot loaded lower patch is presented to improve isolation between the two polarisation ports. Simulations and measurements show two linear polarisations with an isolation of more than 30 dB within the band 2.5-2.7 GHz. A return loss of -10 dB is achieved within the above-mentioned bandwidth for the proposed antenna. The radiation pattern for the antenna is similar to that of a conventional microstrip antenna and the measured cross-polar level is 16.5 dB below the peak co-polar level within the band 2.5-2.7 GHz.
TL;DR: In this paper, an internal antenna covering seven frequency bands is presented for personal communication handsets, which operates at GSM (880-960 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2170 MHz), WiBro (2300-2390 MHz), Bluetooth (2.4-2.48 GHz), and WLAN (5.0-5.5 GHz) frequency bands.
Abstract: Modern personal communication handsets are shrinking in size and are required to operate at multiple frequency bands for enhanced functionality and performance. This poses an important challenge for antenna designers to build multiband antennas within the limited allowable space. In this paper, an internal antenna covering seven frequency bands is presented for personal communication handsets. The proposed antenna operates at GSM (880-960 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2170 MHz), WiBro (2300-2390 MHz), Bluetooth (2.4-2.48 GHz), and WLAN (5.0-5.5 GHz) frequency bands. Measured input return loss of the antenna is better than dB at all the frequency bands with reasonable radiation performance. Antenna volume is 30 mm times15 mm times 4.0 mm (1.8 cm) that makes it attractive for modern multiband and multifunctional slim handsets.
TL;DR: By using the genetic algorithm based on fuzzy decision-making, some modifications have been implemented to the incorporated slots which lead to even more enhancement in the antenna bandwidth which is larger than that of a corresponding unslotted rectangular microstrip antenna or a conventional E-Shaped patch antenna.
Abstract: In this paper a novel form of the familiar E-shaped patch antenna is presented. In the presented approach, by using the genetic algorithm (GA) based on fuzzy decision-making, some modifications have been implemented to the incorporated slots which lead to even more enhancement in the antenna bandwidth. The MOM (Method of Moment) is employed for analysis at the frequency band of 1.8GHz---2.6GHz by the optimization parameters of supply locations and slot dimensions. In the implemented fuzzy system, inputs are parameters like population, and outputs are parameters like recombination to produce the next generation. Fuzzy inference system (FIS) is used for the control of GA parameters. The design is also optimized by successive iterations of a computer-aided analysis package and experimental modifications. Prototype antenna, resonating at wireless communication frequencies of 1.88 and 2.37 GHz, has been constructed and experimental results are in relatively good agreement with the analysis. Dimensions of the modified slots for bandwidth enhancement, while maintaining good radiation characteristics, have been determined and the obtained antenna bandwidth of 36.7% is larger than that of a corresponding unslotted rectangular microstrip antenna or a conventional E-Shaped patch antenna. Details of the antenna design approach and experimental results are presented and discussed.
TL;DR: In this article, a simple design of a probe-feed microstrip antenna with circular polarization (CP) radiation is presented, by embedding dual slits in a square microstrip and adjusting the sizes of the slits.
Abstract: A simple design of a probe-feed microstrip antenna with circular polarization (CP) radiation is presented. By embedding dual slits in a square microstrip and adjusting the sizes of the slits, an H-shaped microstrip antenna with two near-degenerate orthogonal modes for CP radiation can be achieved. This design provides a wide CP bandwidth and relaxed fabrication tolerances. Details of the antenna design are described, and theoretical and experimental results of the CP performance are presented.
TL;DR: In this paper, the design of a patch antenna working in E5-L1 Galileo, 2.5 and 3.5 GHz Wi-Max bands is discussed starting from a classical rectangular patch antenna with four resonant modes located around the required spectrum regions, the tuning of the operating frequencies is obtained by perturbing the perimeter of the antenna shape according to a prefractal Koch-like erosion process.
Abstract: The design of a patch antenna working in E5-L1 Galileo, 2.5 and 3.5 GHz Wi-Max bands is discussed. Starting from a classical rectangular patch antenna with four resonant modes located around the required spectrum regions, the tuning of the operating frequencies is obtained by perturbing the perimeter of the antenna shape according to a pre-fractal Koch-like erosion process. To show the effectiveness and reliability of the synthesised structure, a selected set of numerical and experimental results are reported and discussed.
TL;DR: In this article, a printed folded slot antenna suitable for GSM/DCS/PCS/UMTS multiband operation in the mobile phone is presented, which has a planar configuration and is easy to fabricate by printing on the system circuit board of mobile phone.
Abstract: A novel printed folded slot antenna suitable for GSM/DCS/PCS/UMTS multiband operation in the mobile phone is presented. The proposed slot antenna has a planar configuration and is easy to fabricate by printing on the system circuit board of the mobile phone. The slot antenna has a length of 106 mm and is folded into a compact structure with its two slot ends facing toward each other. This configuration allows the antenna to occupy a small area of 21 × 45 mm2 centered on the top portion of the system ground plane. By feeding the slot antenna using a 50 Ω microstrip line printed along the centerline of the system ground plane, two wide bands (the half- and one-wavelength modes) of the antenna can be generated, with the lower band covering GSM operation and the upper band covering DSC/PCS/UMTS operation. In addition, small excited surface currents in the system ground plane are observed, and the antenna's two operating bands are in general not sensitive to the ground-plane length variations. These features are attractive for practical applications and different from those of the conventional internal mobile phone antennas. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1833–1837, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22602
Patent•
27 Jun 2007TL;DR: In this article, an antenna module for a mobile terminal including a non-resonant antenna element (102), two resonant antenna elements (104, 106) each covering at least any one of a first, second, third and fourth frequency band, was described.
Abstract: The invention relates to a radio antenna (100) and, more specifically, to an internal multiband antenna for use, e.g., in a portable telecommunication device, such as a mobile phone. In particularly the invention relates to an antenna module for a mobile terminal including a non-resonant antenna element (102), two resonant antenna elements (104, 106) each covering at least any one of a first, second, third and fourth frequency band, said two resonant elements are substantially in the same plane and define a planar surface wherein the two resonant elements (104, 106) are each positioned at a corner of the planar surface and the non-resonant element (102) is positioned along an edge of the planar surface.
09 Jun 2007
TL;DR: In this paper, a microstrip patch antenna on a dielectric substrate with CSRRs employed in the ground plane, and examine the resonant frequency, impedance bandwidth, and radiation characteristics.
Abstract: In this paper, we investigate a microstrip patch antenna on a dielectric substrate with CSRRs employed in the ground plane, and examine the resonant frequency, impedance bandwidth, and radiation characteristics. The comparison of the impedance bandwidth between the microstrip patch antenna on a conventional high permittivity substrate and with the CSRR substrate is presented. The experimental results demonstrated that significant size reduction is possible for a microstrip antenna without sacrificing the bandwidth by using the CSRR loaded ground plane. The fabricated antenna achieves a 69% reduction in the resonant frequency as well as 67% improvement in the bandwidth compared to the conventional antenna.
Patent•
28 Aug 2007TL;DR: In this article, a PIFA resonating element is used to support a hybrid PIFA-slot antenna, which is formed from a ground plane having a dielectric-filled slot that defines a slot antenna structure and having a planar-inverted-F (PIFA) resonance element located above the opening.
Abstract: Handheld electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include an antenna. The antenna may be formed from a ground plane having a dielectric-filled slot that defines a slot antenna structure and having a planar-inverted-F (PIFA) resonating element located above the opening. The slot antenna structure and the PIFA resonating element may both contribute to the performance of the antenna, so that the antenna exhibits the performance of a hybrid PIFA-slot antenna. The PIFA resonating element may contain multiple antenna resonating element branches. The branches may be configured to operate in different communications bands than the slot antenna structure.
TL;DR: In this paper, a self-complementary structure of the same miniaturized topology was proposed to moderate the frequency dependence of the antenna input impedance. But, the authors only evaluated the effect of the self-compensated structure on the performance of the folded slot antenna.
Abstract: Folded and self-complementary structures are considered as two effective approaches to increase the bandwidth of miniaturized antennas. A folded realization of a previously reported miniaturized slot antenna is devised and shown to provide more than 100% increase in the bandwidth as compared with that of the miniaturized slot antenna with the same size and efficiency. The complementary pair of the miniaturized folded slot, namely, the folded printed wire is also discussed in this paper. It is shown that the folded slot has a much higher radiation efficiency when compared with its complementary folded wire antenna. Another approach for bandwidth improvement is the implementation of the self-complementary structure of the same miniaturized topology to moderate the frequency dependence of the antenna input impedance. To examine this approach, a folded self-complementary miniature antenna is studied, where further increase in bandwidth is observed. A miniaturized folded slot, its complementary miniaturized folded printed wire, as well as their self-complementary realization, were fabricated and tested. These antennas can fit into a very small rectangular area with dimensions as small as 0.065lambdao x 0.065lambdao. While the folded slot ranks the highest in the efficiency/gain, the self-complementary structure falls between the slot and printed wire since it consists of equal proportions of the both slots and strips. A self-complementary H-shape antenna is also introduced to demonstrate that by relaxing the miniaturization to a moderate value, a significant improvement in bandwidth can be accomplished. With yet small dimensions of 0.13lambdao x 0.24lambdao, a very wide bandwidth of (2.3:1) is obtained. For the case of no dielectric substrate, even wider bandwidth of (3:1) is achievable.