Showing papers on "Dipole antenna published in 2014"

Study and prototyping of practically large-scale mmWave antenna systems for 5G cellular devices

Abstract: This article discusses the challenges, benefits and approaches associated with realizing largescale antenna arrays at mmWave frequency bands for future 5G cellular devices. Key design considerations are investigated to deduce a novel and practical phased array antenna solution operating at 28 GHz with near spherical coverage. The approach is further evolved into a first-of- a-kind cellular phone prototype equipped with mmWave 5G antenna arrays consisting of a total of 32 low-profile antenna elements. Indoor measurements are carried out using the presented prototype to characterize the proposed mmWave antenna system using 16-QAM modulated signals with 27.925 GHz carrier frequency. The biological implications due to the absorbed electromagnetic waves when using mmWave cellular devices are studied and compared in detail with those of 3/4G cellular devices.

A Compact, Low-Profile Metasurface-Enabled Antenna for Wearable Medical Body-Area Network Devices

Abstract: We propose a compact conformal wearable antenna that operates in the 2.36-2.4 GHz medical body-area network band. The antenna is enabled by placing a highly truncated metasurface, consisting of only a two by two array of I-shaped elements, underneath a planar monopole. In contrast to previously reported artificial magnetic conducting ground plane backed antenna designs, here the metasurface acts not only as a ground plane for isolation, but also as the main radiator. An antenna prototype was fabricated and tested, showing a strong agreement between simulation and measurement. Comparing to previously proposed wearable antennas, the demonstrated antenna has a compact form factor of 0.5 λ 0 ×0.3 λ 0 ×0.028 λ 0 , all while achieving a 5.5% impedance bandwidth, a gain of 6.2 dBi, and a front-to-back ratio higher than 23 dB. Further numerical and experimental investigations reveal that the performance of the antenna is extraordinarily robust to both structural deformation and human body loading, far superior to both planar monopoles and microstrip patch antennas. Additionally, the introduced metal backed metasurface enables a 95.3% reduction in the specific absorption rate, making such an antenna a prime candidate for incorporation into various wearable devices.

A Broadband Dual-Polarized Planar Antenna for 2G/3G/LTE Base Stations

Abstract: A broadband dual-polarized planar antenna is proposed for 2G/3G/LTE base stations. The dual-polarized antenna is composed of two perpendicularly crossed bow-tie dipoles. Each bow-tie dipole is excited by a microstrip stub that is directly fed by a coaxial line, making the dual-polarized antenna full planar. Due to the coupling between two crossed bow-tie dipoles, a broad bandwidth is achieved. It is shown that the dual-polarized antenna has a bandwidth of 45% (1.7-2.7 GHz) for return loss >15 dB with an isolation of higher than 30 dB between two polarization input ports. The dual-polarized antenna has a half-power beam width (HPBW) of around 65 ° and an average gain of 8.5 dBi for slant ±45° polarizations. An 8-element dual-polarized planar antenna array is developed for base station applications. A bandwidth of 56% (1.63-2.9 GHz) is obtained for the antenna array. The antenna gain of the array is about 16 dBi and the HPBW is 65±8° for each polarization.

Experimental circular phased array for generating OAM radio beams

Abstract: A circular phased array antenna that can generate orbital angular momentum (OAM) radio beams in the 10 GHz band is described. The antenna consists of eight inset-fed patch elements and a microstrip corporate feeding network. A full-wave electromagnetic simulator is used to aid the antenna design and theoretical simulations are confirmed by measurements.

Hybrid Fractal Shape Planar Monopole Antenna Covering Multiband Wireless Communications With MIMO Implementation for Handheld Mobile Devices

Abstract: A hybrid fractal shape planar monopole antenna covering multiple wireless communication bands is presented for multiple-input-multiple-output (MIMO) implementation for handheld mobile devices. The proposed structure is the combination of Minkowski island curve and Koch curve fractals. It is placed with edge to edge separation of 0.16λ0 at 1.75 GHz. The T-shape strip is inserted and rectangular slot is etched at top side of ground plane, respectively to improve the impedance matching and isolation between the antennas. A measured impedance matching fractional bandwidths ( S11 ≤ -10 dB) are 14% from 1.65 GHz to 1.9 GHz for the band 1 and 80% from 2.68 GHz to 6.25 GHz for the band 2. Acceptable agreement is obtained between the simulated and measured antenna performance parameters. These characteristics demonstrate that the proposed antenna is an attractive candidate for handheld mobile devices.

A Compact Microstrip-Fed Triple Band-Notched UWB Monopole Antenna

Abstract: In this letter, a novel low-profile microstrip-fed compact triple band-notched ultrawideband (UWB) antenna is proposed. Notch bands around the 3.3-3.8-GHz WiMAX and 5.15-5.85-GHz WLAN frequencies are obtained by etching out two elliptic single complementary split-ring resonators (ESCSRRs) of different dimensions from the radiating patch of the antenna. Furthermore, by placing two rectangular split-ring resonators near the feedline-patch junction of the antenna, rejection for the 7.9-8.4-GHz X-band frequencies is achieved. Design guidelines for implementing the notch-bands at the desired frequency regions are provided. The match between the simulated and experimental results suggests that the proposed antenna can be a good candidate for application in UWB communication systems.

Capacitively Loaded Circularly Polarized Implantable Patch Antenna for ISM Band Biomedical Applications

Abstract: A single-fed miniaturized circularly polarized microstrip patch antenna is designed and experimentally demonstrated for industrial-scientific-medical (2.4-2.48 GHz) biomedical applications. The proposed antenna is designed by utilizing the capacitive loading on the radiator. Compared with the initial topology of the proposed antenna, the so-called square patch antenna with a center-square slot, the proposed method has the advantage of good size reduction and good polarization purity. The footprint of the proposed antenna is 10×10×1.27 mm3. The simulated impedance, axial ratio, and radiation pattern are studied and compared in two simulation models: cubic skin phantom and Gustav voxel human body. The effect of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The effect of coaxial cable is also discussed. Two typical approaches to address the biocompatibility issue for practical applications are reported as well. The simulated and measured impedance bandwidths in cubic skin phantom are 7.7% and 10.2%, respectively. The performance of the communication link between the implanted CP antenna and the external antenna is also presented.

A CMOS 210-GHz Fundamental Transceiver With OOK Modulation

Abstract: This paper presents a 210-GHz transceiver with OOK modulation in a 32-nm SOI CMOS process (fT/fmax= 250/320 GHz). The transmitter (TX) employs a 2 × 2 spatial combining array consisting of a double-stacked cross-coupled voltage controlled oscillator (VCO) at 210 GHz with an on-off-keying (OOK) modulator, a power amplifier (PA) driver, a novel balun-based differential power distribution network, four PAs, and an on-chip 2 × 2 dipole antenna array. The noncoherent receiver (RX) utilizes a direct detection architecture consisting of an on-chip antenna, a low-noise amplifier (LNA), and a power detector. The VCO generates measured -13.5-dBm output power, and the PA shows a measured 15-dB gain and 4.6-dBm Psat. The LNA exhibits a measured in-band gain of 18 dB and minimum in-band noise figure (NF) of 11 dB. The TX achieves an EIRP of 5.13 dBm at 10 dB back-off from saturated power. It achieves an estimated EIRP of 15.2 dBm when the PAs are fully driven. This is the first demonstration of a fundamental frequency CMOS transceiver at the 200-GHz frequency range.

Compact Coradiator UWB-MIMO Antenna With Dual Polarization

Abstract: Two compact coradiator multiple-input-multiple-out (MIMO) antennas operating in the UWB frequency band with dual polarization are proposed. Different from traditional MIMO antennas, the radiator is shared by two antenna elements, which greatly reduce the overall size of the MIMO system. High isolation between the two antenna elements is achieved by etching a T-shaped slot in the radiator and extending a stub on the ground. Dual polarization can be realized by exciting the pentagonal radiator with perpendicular feeding structure. The simulated results of current and electric-field distribution show the dual-polarization characteristics of the diversity system. Besides, a four units UWB MIMO antenna is also proposed. Furthermore, the diversity characteristics of mean effective gains (MEGs) and diversity gain (DG) are also studied. The simulated and measured results demonstrate that the UWB-MIMO antenna has good impedance matching, isolation and dual polarization characteristics.

A Coupled Resonator Decoupling Network for Two-Element Compact Antenna Arrays in Mobile Terminals

Abstract: A new concept for decoupling two coupled antenna elements in a broad band using a coupled resonator decoupling network (CRDN) is proposed for the first time. A synthesis and design theory of a CRDN is presented. Based on the admittance parameters of a given antenna array, a set of required rational functions and, consequently, the coupling matrix for a second-order decoupling network is obtained analytically. To prove the concept, two prototypes using microstrip resonators are designed and experimentally studied. Measurement results have demonstrated that an isolation improvement of more than 10 dB can be achieved within more than 15% bandwidth in both examples. The benefits of using a CRDN for different levels of isolation in a MIMO terminal are investigated through experiments and simulations. The results have shown that, as compared to the existing decoupling scheme using a lumped element, the proposed CRDN scheme can significantly increase the radiation efficiency, reduce the correlation, improve the channel capacity, and above all enhance the throughput of a MIMO terminal. The technique is general and can be applied to both symmetric and asymmetric arrays.

Antenna arrangement for pocket-forming

Abstract: The present disclosure describes a plurality of antenna arrangements that may be suitable for wireless power transmission based on single or multiple pocket-forming. Single or multiple pocket-forming may include one transmitter and at least one or more receivers, being the transmitter the source of energy and the receiver the device that is desired to charge or power. The antenna arrangements may vary in size and geometry, and may operate as a single array, pair array, quad arrays or any other suitable arrangement, which may be designed in accordance with the desired application.

Design of Orthogonal MIMO Handset Antennas Based on Characteristic Mode Manipulation at Frequency Bands Below 1 GHz

Abstract: Multi-antenna design in compact mobile handsets at frequency bands below 1 GHz is very challenging, since severe mutual coupling is commonly induced by simultaneous excitation of the chassis' fundamental dipole mode by more than one antenna element. To address this problem, a novel multi-antenna design approach is proposed herein to obtain efficient and uncorrelated antennas. By manipulating the chassis structure, more than one characteristic mode is enabled to resonate at frequencies below 1 GHz. With proper excitations for different characteristic modes, which are orthogonal to each other, well matched multi-antennas with low coupling and correlation are achieved. A chassis loaded with two T-shaped metal strips above its longer edges is taken as an example modification to illustrate the effectiveness of the proposed design approach at 900 MHz. This modification creates a new characteristic mode which resonates near 900 MHz. Afterward, two antenna feeds were designed to efficiently excite the chassis' fundamental dipole mode and the T-strip mode with very low correlation. The T-strip antenna covers LTE Band 8 (880-960 MHz), and the dipole mode antenna covers both LTE Band 5 (824-894 MHz) and LTE Band 8. The proposed dual-antenna design was found to outperform a reference design significantly, both with and without user interactions (i.e., one-hand and two-hand data grips). Practical aspects of mobile handset antennas are also investigated. The prototype was also fabricated and measured, and the measured results show reasonable agreements with the simulated results.

Compact SRR loaded UWB circular monopole antenna with frequency notch characteristics

Abstract: This paper presents the design of a compact split ring resonator (SRR) loaded coplanar waveguide (CPW) fed ultrawideband circular monopole antenna having frequency notch characteristics. The electromagnetic coupling of the SRR with the CPW yields the frequency notch. Fabricated prototypes were measured and compared with simulations and good agreement was obtained. The impedance and radiation plots confirm the suppression of the desired notch frequency. A theoretical formulation to calculate the notch frequency is also proposed and validated.

W-Band Large-Scale High-Gain Planar Integrated Antenna Array

Abstract: This communication presents a 32 $\,\times\,$ 32 high-gain patch array antenna fed by the substrate integrated waveguide (SIW) structure at W-band. The array antenna consists of two layers to achieve a compact topology, which allows for mass production using a standard PCB fabrication process. The wideband feeding network is placed in the bottom layer while the radiating patches are on the top layer. This configuration also resolves the trade-off between gain and bandwidth of conventional SIW array antennas. Measured gain of the 32 $\,\times\,$ 32 antenna array is within the range 28.81–29.97 dBi in the working bandwidth of 91–97 GHz. Measured impedance bandwidth covers the same frequency band for $\vert {\rm S} _{11} \vert . The cross-polarization of the antenna array is less than 40 dB at the beam direction. Good agreement between the simulated and measured results validates our design.

Low-Cost Wideband Microstrip Antenna Array for 60-GHz Applications

Abstract: A low-cost single-layer wideband microstrip antenna array is presented for 60-GHz band applications. Each microstrip radiation element is fed by a modified L-shaped probe to enhance the impedance bandwidth. The proposed microstrip antenna array is excited by a novel coplanar waveguide (CPW) feed network, which not only has a simple structure by abandoning the traditional air bridges (wire bonds) above the CPW T-junctions but also provides pairs of broadband differential outputs. Experimentally, two 4 $\,\times\,$ 4 antenna arrays with different polarizations were designed and fabricated on the double-sided single-layer printed circuit board. The linearly polarized array exhibits an impedance bandwidth ( ${\hbox{SWR}}\leq 2$ ) of 25.5% and a gain of around 15.2 dBi. The circularly polarized array, employing the same CPW feed network to excite sequentially rotated circularly polarized elements, achieves an impedance bandwidth ( ${\hbox{SWR}}\leq 2$ ) of 17.8%, a 3-dB axial ratio bandwidth of 15.6%, and a gain of around 14.5 dBi.

Low-Profile Dual-Band Textile Antenna With Artificial Magnetic Conductor Plane

Abstract: A dual-band textile antenna loaded with an artificial magnetic conductor (AMC) plane is proposed for WLAN applications. Its dual-band operation is enabled by a rectangular patch in the 2.4 GHz band and a patch-etched slot dipole in the 5 GHz band. Since the AMC approaches a perfect magnetic conductor (PMC) in the 5 GHz band, the slot dipole can be located close to the ground. The proposed antenna is fully fabricated using textiles except for a feeding connector used for testing purposes and a via. Simulations and experiments agree well and validate that this low profile antenna operates with a good reflection coefficient and a high front-to-back ratio (FBR) within the desired bands.

A Low-RCS and High-Gain Partially Reflecting Surface Antenna

Abstract: We propose a novel design to reduce the radar cross section (RCS) and enhance the gain of a patch antenna by using partially reflecting surface (PRS). The PRS consists of two layers of metallic patterns on both sides of a dielectric slab. The metallic pattern on the bottom side is utilized to construct Fabry-Perot resonance cavity with ground plane of a patch antenna, while it is designed to absorb most of the incident wave on the top side. The PRS can enable the patch antenna to simultaneously achieve high gain and low RCS. Measurement results show that the antenna gain is enhanced by about 6.5 dB at 11.5 GHz, and its RCS is dramatically reduced in a broad frequency range from 6 to 14 GHz, compared with the traditional patch antenna without the PRS.

A Wideband Circularly Polarized Cross-Dipole Antenna

Abstract: This letter introduces a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45-GHz ISM band wireless communications. Unlike conventional cross-dipole antennas, the proposed cross dipole is designed with wide open ends such that both impedance and axial-ratio (AR) bandwidths are enhanced. In addition, to excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at the corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. The antenna is center-fed by a 50- Ω coaxial cable and is placed above a square reflector to obtain a directional CP radiation pattern. With the advantage of centered feed, symmetric CP radiation patterns can be achieved across the entire operating bandwidth. Simulated and measured results confirm the proposed antenna produced good CP characteristics. An impedance bandwidth (for VSWR ≤ 2) of about 50.2% (1.99-3.22 GHz) and the 3-dB AR bandwidth of about 27% (2.30-2.9 GHz) around the center frequency of 2.45 GHz were measured. The antenna has an average CP gain of 6.2 dBic across the operating bandwidth and the maximum gain of 6.8 dBic at the center frequency. The size of antenna is 0.45λ×0.45λ×0.24λ.

Dynamically Adjusting Width Of Beam Based On Altitude

Abstract: An antenna includes a radiator and a reflector and has a radiation pattern that is based at least in part on a separation distance between the radiator and the reflector. The antenna includes a linkage configured to adjust the separation distance based at least in part on the altitude of the antenna. The resulting radiation pattern can be dynamically adjusted based on altitude of the antenna such that, while the antenna is aloft and the antenna is ground-facing, variations in geographic boundaries and intensity of the radiation received at ground level are at least partially compensated for by the dynamic adjustments to the radiation pattern.

High-Gain and Broadband Transmitarray Antenna Using Triple-Layer Spiral Dipole Elements

Abstract: A triple-layer transmitarray antenna has been designed, fabricated, and tested at X-band. Using a spiral-dipole element, a full transmission phase range of 360 ° is achieved for a transmission magnitude equal to or better than -4.2 dB. The transmission phase distribution of the transmitarray elements has been optimized to reduce the effects of the lossy elements with low transmission magnitudes on the antenna gain, leading to an average element loss as low as 0.49 dB. The measured gain of the transmitarray prototype is 28.9 dB at 11.3 GHz, resulting in a 30% aperture efficiency. Antenna bandwidths of 9% for 1-dB gain and 19.4% for 3-dB gain are achieved in this design.

Circularly Polarized Helical Antenna for ISM-Band Ingestible Capsule Endoscope Systems

Abstract: A multilayer miniaturized circularly polarized (CP) helical antenna is designed and experimentally demonstrated for industrial, scientific, and medical (ISM) (2.4-2.48 GHz) ingestible capsule endoscope systems. The proposed antenna is composed of three open loops at various layers connected by via holes to form an axial-mode helical structure to generate traveling wave radiation. A one-layer muscle phantom model is used for initial design and optimization. The footprint of the proposed antenna is π×(5.5) 2 ×3.81 mm 3 . The simulated and measured impedance bandwidth is over 40% and 26% in the one-layer muscle phantom, respectively. The simulated axial ratio (AR) bandwidth is around 33.3%. The CP purity of the proposed antenna is calculated by comparing the communication link levels for two orthogonal polarizations. Additionally, electrical components are modeled inside the capsule to evaluate the effects on the antenna performance. CST voxel Gustav human body is utilized to study the design in a realistic environment. Finally, an omnidirectional CP exterior antenna is designed and the communication link is evaluated.

A Compact Dual-Polarized Printed Dipole Antenna With High Isolation for Wideband Base Station Applications

Abstract: A compact dual-polarized printed dipole antenna for wideband base station applications is presented in this communication. The proposed dipole antenna is etched on three assembled substrates. Four horizontal triangular patches are introduced to form two dipoles in two orthogonal polarizations. Two integrated baluns connected with 50 Ω SMA launchers are used to excite the dipole antenna. The proposed dipole antenna achieves a more compact size than many reported wideband printed dipole and magneto-electric dipole antennas. Both simulated and measured results show that the proposed antenna has a port isolation higher than 35 dB over 52% impendence bandwidth (VSWR <; 1.5). Moreover, stable radiation pattern with a peak gain of 7 dBi - 8.6 dBi is obtained within the operating band. The proposed dipole antenna is suitable as an array element and can be used for wideband base station antennas in the next generation IMT-advanced communications.

Method and apparatus for high-performance compact volumetric antenna with pattern control

Abstract: A wide-bandwidth antenna with antenna pattern control includes a radiator and a feed. The radiator includes two or more volumetric radiating elements. The feed includes two or more feed units, the feed units configured to provide wave signals to the volumetric radiating elements. The feed units provide an independent signal for each radiating element. The wave signals can be fed out of phase to each other. Depending on the dielectric filler inside the volume of the antenna and the phase shift between feeds, the pattern can be modified electronically leading to pattern control. The radiating elements are spaced at a distance at least one order of magnitude smaller than half of an operational wavelength of the antenna. At least one electrically conductive element of the antenna is capable of conducting a current that generates a magnetic field. The magnetic field lowers the total reactance of the antenna, thereby resulting in enhanced performance of the antenna in terms of bandwidth, gain, and pattern control. The volumetric design allows miniaturization of the antenna.

Wideband Millimeter-Wave Substrate Integrated Waveguide Cavity-Backed Rectangular Patch Antenna

Abstract: In this letter, a new type of wideband substrate integrated waveguide (SIW) cavity-backed patch antenna and array for millimeter wave (mmW) are investigated and implemented. The proposed antenna is composed of a rectangular patch with a backed SIW cavity. In order to enhance the bandwidth and radiation efficiency, the cavity is designed to resonate at its TE210 mode. Based on the proposed antenna, a 4 × 4 array is also designed. Both the proposed antenna and array are fabricated with standard printed circuit board (PCB) process, which possess the advantage of easy integration with planar circuits. The measured bandwidth (|S11| ≤ -10 dB) of the antenna element is larger than 15%, and that of the antenna array is about 8.7%. The measured peak gains are 6.5 dBi for the element and 17.8 dBi for the array, and the corresponding simulated radiation efficiencies are 83.9% and 74.9%, respectively. The proposed antenna and array are promising for millimeter-wave applications due to its merits of wide band, high efficiency, low cost, low profile, etc.

A Novel Broadband Dual-Polarization Antenna Utilizing Strong Mutual Coupling

Abstract: A novel broadband dual-polarization antenna utilizing strong mutual coupling with high isolation is presented in this communication. The antenna is composed of two orthogonally situated dipoles which have square-loop shape arms (SLSAs). And to shape the radiation pattern of the antenna, a metal reflector is placed under the antenna. By elaborately utilizing the strong mutual coupling between the two dipoles, very good impedance match and sufficiently high isolation can be achieved simultaneously, the reasons for which are analyzed in this communication. Both the simulated and the measured results show that a more than 57.5% impedance bandwidth with SWR 31 dB can be achieved for the proposed antenna. As an important advantage, the input impedance of the antenna can be controlled within certain limits by adjusting the configurations, thus the antenna can be fed directly by coaxial cables without using impedance transformers. Besides, the antenna structure is compact and simple.

Dense Dielectric Patch Array Antenna With Improved Radiation Characteristics Using EBG Ground Structure and Dielectric Superstrate for Future 5G Cellular Networks

Abstract: In this paper, a new dense dielectric (DD) patch array antenna prototype operating at 28 GHz for future fifth generation (5G) cellular networks is presented. This array antenna is proposed and designed with a standard printed circuit board process to be suitable for integration with radio frequency/microwave circuitry. The proposed structure employs four circular-shaped DD patch radiator antenna elements fed by a 1-to-4 Wilkinson power divider. To improve the array radiation characteristics, a ground structure based on a compact uniplanar electromagnetic bandgap unit cell has been used. The DD patch shows better radiation and total efficiencies compared with the metallic patch radiator. For further gain improvement, a dielectric layer of a superstrate is applied above the array antenna. The measured impedance bandwidth of the proposed array antenna ranges from 27 to beyond 32 GHz for a reflection coefficient (S11) of less than -10 dB. The proposed design exhibits stable radiation patterns over the whole frequency band of interest, with a total realized gain more than 16 dBi. Due to the remarkable performance of the proposed array, it can be considered as a good candidate for 5G communication applications.

Low-Cost High-Gain and Broadband Substrate- Integrated-Waveguide-Fed Patch Antenna Array for 60-GHz Band

Abstract: A low-cost high-gain and broadband substrate integrated waveguide (SIW)-fed patch antenna array is demonstrated at the 60-GHz band. A single-layered SIW feeding network with wideband T-junctions and wideband high-gain cavity-backed patch antennas are employed to achieve high gain and wideband performance simultaneously. Although the proposed antenna array has a multilayered structure, it can be fabricated by conventional low-cost single-layered printed circuit board (PCB) technology and then realized by stacking and fixing all of single layers together. The simulated and measured impedance bandwidths of a 4 × 4 antenna array are 27.5% and 22.6% for 10 dB. The discrepancy between simulation and measurement is analyzed. A gain up to 19.6 dBi, and symmetrical unidirectional radiation patterns with low cross polarization are also achieved. With advantages of low fabrication cost and good performances, the proposed antenna array is a promising candidate for millimeter-wave wireless communication systems.

Wideband Radar Cross Section Reduction of Slot Antennas Arrays

Abstract: A comprehensive analysis aimed at reducing the radar cross section (RCS) of array antennas, preserving at the same time their radiating performance, is presented. A microstrip slot array is considered as a test case to illustrate the proposed strategy for radar cross section reduction (RCSR). It is shown that a remarkable reduction of the radar signature can be accomplished over a frequency band as wide as two octaves by employing an array of periodic resistive elements in front of the radiating apertures. The monostatic and bistatic RCS of the proposed structures are investigated both for normal and oblique incidence. Different arrangements and geometries of the periodic resistive pattern are thoroughly analyzed showing the benefits and the drawbacks in terms of antenna gain and level of the scattered fields. Furthermore, the use of metallic parasitic elements for enhancing the antenna gain is considered, and the scattering phenomena caused by their presence are addressed, taking into account the appearance of grating lobes. The antenna designs are also analyzed by resorting to a bidimensional color plot presenting the variation of the reradiated field both in frequency and spatial domain. The guidelines illustrated by the proposed examples can be easily applied to other antenna architectures.

Compact and Small Planar Monopole Antenna With Symmetrical L- and U-Shaped Slots for WLAN/WiMAX Applications

Abstract: A small and compact triple-band microstrip-fed printed monopole antenna for Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) is presented. The proposed antenna consists of a rectangular radiating patch with L- and U-shaped slots and ground plane. A parametric study on the lengths of the U- and L-shaped slots of the proposed antenna is provided to obtain the required operational frequency bands-namely, WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz). The proposed antenna is small (15 × 15 × 1.6 mm 3) when compared to previously well-known double- and triple-band monopole antennas. The simulation and measurement results show that the designed antenna is capable of operating over the 2.25-2.85, 3.4-4.15, and 4.45-8 GHz frequency bands while rejecting frequency ranges between these three bands. Omnidirectional radiation pattern and acceptable antenna gain are achieved over the operating bands.

Design and in Vitro Test of a Differentially Fed Dual-Band Implantable Antenna Operating at MICS and ISM Bands

Abstract: The design of a novel differentially fed dual-band implantable antenna operating at 402-405 MHz Medical Implant Communication Services (MICS) band and 2.4-2.5 GHz Industrial, Scientific, and Medical (ISM) band is introduced. The proposed implanted antennas are for both planar and flexible implantation scenarios. Biocompatible material parylene-C is adopted to cover the implanted antenna. The size of the proposed antennas including the encapsulation for planar and flexible case is 179.0 mm3 and 186.3 mm3 respectively. The Specific Absorption Rate (SAR) distribution and the radiation pattern at both frequencies induced by the implanted antenna are evaluated. The performance of the communication link between the implanted antenna and an external half-wavelength dipole at two resonant frequencies is also presented. In vitro test in minced pork is performed to test the reliability of the antenna in the real implantation cases.