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A compact dual-band circularly polarized (CP) shared-aperture antenna is proposed for satellite communication. The antenna enables simultaneous dual-band functionality and CP radiation with right-handed CP in the Ku band and left-handed CP (LHCP) in the Ka band. The shared-aperture is implemented by integrating two independent subapertures, which function through frequency-multiplexed, resulting in a minimized profile (0.04 $ {\lambda _0} $ λ 0 ) and reduced complexity, making it an ideal choice for array applications. To enhance inter-frequency isolation, a circular arrangement of metal vias is incorporated. The measured results indicate that the antenna effectively encompasses a 3 dB axial ratio (AR) bandwidth of 15.6–16.5 GHz in Ku and 26.5–27.5 GHz in Ka bands. Additionally, it exhibits a broader 10 dB impedance bandwidth (IBW) and superior port isolation bandwidth exceeding 30 dB. [ABSTRACT FROM AUTHOR]

In this study, a wideband circularly polarized (CP) H‐plane horn antenna based on Gap Waveguide (GW) technology in K‐band is presented. The proposed antenna consists of two unconnected metal planes. To produce broadband CP radiation, two main methods are utilized. First, two antipodal tapered plates (ATPs) are added in front of the horn. The ATPs are carefully designed for dissimilar polarization orientations. By this technique, the orthogonal electric fields can be prepared. Then, by embedding three metal square pins near the center of the aperture in both inner plates, the impedance bandwidth (BW) and BW of CP radiation of the proposed horn is entirely improved. Its BW for target |S11| < −10 dB is 18–28 GHz. Also, the peak gain fluctuates between 11.5 and 13 dB. This antenna can provide a 3 dB polarization axial‐ratio BW of about 28.5% (20–26 GHz). Total radiation efficiency is higher than 94%. To verify the design, the proposed structure is manufactured and tested. The proposed horn antenna result has an appropriate agreement between measurement and simulation. Its miniaturized dimensions, easy and cheap fabrication, and broadband CP capability make it a proper volunteer for broadband communication systems. Key Points: We apply Gap Waveguide technology in sectoral horn antenna to reduce the size, bulk, and cost of conventional horn antennasSymmetrical radiation patterns and wideband circular polarization are achieved from two added antipodal tapered plates and three embedded pinsAn antenna is designed for 5G or vehicular satellite communication fields [ABSTRACT FROM AUTHOR]

A miniaturized and wideband circular-polarized (CP) dipole antenna with couple-feed has been developed for 5G base-station applications. In this design, two novel L-shaped short stubs working as the couple feed are introduced to excite the orthogonal dipole with the orthogonal phase difference. Therefore, CP radiation is realized on the orthogonally arranged dipoles. In addition, a stub-loaded square-ring dipole is utilized to generate another resonant frequency at low frequency, which broaden the working bandwidth and achieve the miniaturization design. To further expand the impedance and axial ratio bandwidths, four branch lines are adopted in the center of crossed square-loops dipoles. The proposed CP antenna using couple feed was finally fabricated and tested. The simulated and measured impedance bandwidth for |S11| < −10 dB is 65.0% from 1.55 to 3.05 GHz. The measured 3 dB axial ratio bandwidth is 37.5% (1.95–2.85 GHz). The measured results prove that this CP antenna can be applied to wideband base-station applications. [ABSTRACT FROM AUTHOR]

In this article, a simple design of a stacked patch dual band circular polarized antenna is designed and tested that can be used for GPS L1 (1575.42 MHz) and L2 (1227.6 MHz) applications. The lower patch is designed for L2 band, and the upper patch is designed for L1 band. Circular polarization in the upper patch is achieved by inculcation of corner truncation, and in lower patch it is achieved by inclusion of both corner truncation and an I-slot. A peak gain of 5.5 and 4.5 dBic is achieved at L1 and L2 bands with a broad beam required for GPS applications. It exhibits a minimal axial ratio of 0.6 dB. The fabricated prototype is experimented. In addition, a parametric analysis was performed to study the impact of antenna performance due to various geometrical parameters. [ABSTRACT FROM AUTHOR]

Achromatic devices present unique capabilities in efficient manipulation of waves and have wide applications in imaging and communication systems. However, the research of achromatic devices is limited by the narrow bandwidth, low efficiency as well as large configurations. In this paper, we propose a general strategy to design spin-locked achromatic metasurface with broadband and high efficiency properties in microwave region. A multi-resonant model is used to control the dispersion within a wide bandwidth by tuning its resonant intensity, resonance numbers as well as resonant frequency. As a proof of the concept, two achromatic meta-devices with ultra-thin profile at microwave frequency are experimentally investigated. The achromatic deflector can reflect the normal incident waves to the same angle within 9.5 to 11.5 GHz, while the other achromatic lens can focus the excitations at the same focal points. The experimentally working efficiency of the meta-devices fluctuates around 71–82% and 57–65% within the target working bandwidth, respectively. Moreover, our meta-devices can preserve the charity of the excitations. The scheme of this research shows great advances in the design of broadband and high-efficiency achromatic devices which can also be applied to other frequency ranges and inspires the realization of ultrabroadband and high-efficiency metadevices.

As a device for missile-borne system to transmit and receive electromagnetic waves, the functions of missile-borne antenna are becoming more and more abundant. The shared-aperture antenna can improve the aperture utilization rate of missile seeker and can avoid radiation interference between antennas. This paper proposes a low profile circularly polarized shared-aperture antenna for missile seeker antenna based on the theory of microstrip circular polari-zed antenna. More specifically, the sequential rotation feed technology is adopted for the rectangular microstrip antenna in the high-frequency C-band part, while the orthogonal double feed technology is adopted for the cross microstrip antenna in the low-frequency S-band part. The nested shared-aperture antenna structure is adopted to realize the design of shared aperture antenna of 63 mm×63 mm×1.574 mm. The reflection coefficient is less than -10 dB in the frequency bands of 4.87~5.13 GHz and 2.49~2.51 GHz. The relative bandwidth of high-frequency antenna is 8.1% and that of low-frequency antenna is 0.4%. The axial ratio of the two antennas in the maximum radiation direction at the center frequency is less than 3 dB. The experimental data show that the shared-aperture antenna designed and applied to the missile-borne antennacan significantly improve the aperture utilization of the missile seeker, and can also eliminate the deterioration of the radiation performances caused by the mutual coupling of antennas.

Achromatic devices present unique capabilities in efficient manipulation of waves and have wide applications in imaging and communication systems. However, the research of achromatic devices is limited by the narrow bandwidth, low efficiency as well as large configurations. In this paper, we propose a general strategy to design spin-locked achromatic metasurface with broadband and high efficiency properties in microwave region. A multi-resonant model is used to control the dispersion within a wide bandwidth by tuning its resonant intensity, resonance numbers as well as resonant frequency. As a proof of the concept, two achromatic meta-devices with ultra-thin profile at microwave frequency are experimentally investigated. The achromatic deflector can reflect the normal incident waves to the same angle within 9.5 to 11.5 GHz, while the other achromatic lens can focus the excitations at the same focal points. The experimentally working efficiency of the meta-devices fluctuates around 71–82% and 57–65% within the target working bandwidth, respectively. Moreover, our meta-devices can preserve the charity of the excitations. The scheme of this research shows great advances in the design of broadband and high-efficiency achromatic devices which can also be applied to other frequency ranges and inspires the realization of ultrabroadband and high-efficiency metadevices. [ABSTRACT FROM AUTHOR]

In this work, the design and performance of a circularly polarized (CP) antenna designed using characteristic modal analysis (CMA) for military band application is presented. The substrate used is single-sided glass-reinforced epoxy and the antenna dimensions are 37×37×1.6 mm3. The antenna is compact, low-profile, circular polarized having an ARBW of around 500 MHz (center frequency 4.6 GHz). A coplanar waveguide (CPW) fed monopole antenna is used for excitation of the modified-square slot antenna that incorporates quarter section of circular symmetrical patches on the four corners. A stub orthogonal to the CPW fed monopole capacitively tunes the low Q mode as identified by CMA technique to shift to a lower frequency to create degenerate modes in military band for circular polarization generation. The 3-dB AR bandwidth of the antenna is in the frequency range 4.43-4.9 GHz and measured value of impedance bandwidth is 3.33 GHz. The fractional ARBW and impedance BW are 10.07 % and 61.6 % respectively. The peak antenna gain in the CP frequency band is 3.75 dBic. The proposed antenna exhibits good polarization purity, the minimum axial ratio is 1.38 at 4.6 GHz. The broad circular polarized antenna is suited for military applications covering the frequency range 4.43-4.9 GHz. [ABSTRACT FROM AUTHOR]

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This paper introduces a wideband circularly polarized rectenna that can harvest efficiently ambient wireless power with bandwidth from 1.7 to 2.6 GHz in both wide operating power and output load ranges. The rectenna is based on a high gain wideband slot microstip receiving antenna array and a wideband rectifier with a branch-line coupler that appropriately improve the RF-dc conversion efficiency at ambient wireless power level in a wide input power range, working frequency and a wide load impedance range. The circular polarization is obtained using by corner perturbation on a square radiation patch and has a bandwidth for axial ratio < 6 dB from 1.65 to 2.76 GHz. An example of the antenna and rectifier circuit have been designed, fabricated and tested. In the proposed rectifier, a peak efficiency of 69% with 12 dBm input power and 64% with 10 dBm input is obtained for a load of 1 KΩ at 1.85 and 2.45 GHz, respectively. The efficiency and dc output of the proposed rectenna is also measured at different frequencies and received power levels with a load resistance of 1 kΩ. The rectenna depicts well performance for the real applications with a much-easy configuration and decreased cost. [ABSTRACT FROM AUTHOR]

In this work, broadband circularly polarized monopole antenna is proposed. The proposed antenna is designed by an FR4 substrate with a dielectric constant of 4.4 and thickness h = 1.6 mm . The size of the designed antenna is 0.99 λ 0 × 0.99 λ 0 × 0.07 λ 0 , where λ 0 is the free space wavelength at the center frequency of f 0 = 12.36 GHz . A stub and a parasitic strip are loaded at the optimum positions on the ground plane to improve the results. The stub and parasitic strip helps to develop two orthogonal modes with the same amplitude for circular polarization. The proposed antenna offers − 10 dB simulated impedance bandwidth of 126% (4.55–20.16 GHz) and measured more than 129% (4.4–20.5 GHz). The 3-dB axial-ratio bandwidth (ARBW) of the monopole antenna is significantly enhanced by using a modified planar ground structure under the proposed patch. There are two 3-dB simulated and measured axial-ratio bandwidth (ARBW) of 86.5% (5.51–13.91 GHz), 16.7% (17.77–21 GHz) and 86.54% (5.5–13.89 GHz), more than 16.71% (17.76–21 GHz) achieved. The fabricated antenna is strongly desirable for WLAN (5.2–5.8 GHz), WiMAX (5.7–5.85 GHz), X-band (8–12 GHz), Ku-band (12–18 GHz) and fractional part of the K-band applications of wireless communication. [ABSTRACT FROM AUTHOR]

In this work, the design and the characterization of a broadband circular polarized monopole having low-profile and wide axial ratio beamwidth were presented. The antenna was designed on readily available, inexpensive glass-reinforced epoxy substrate having an overall size of 0.56λ0×0.50λ0×0.029λ0 (at center frequency 5.5 GHz). The proposed antenna was a modification of a square-shaped monopole antenna, which incorporates a pair of peripheral slits and an off-center slot for a elliptical polarized radiation. A v-shaped notch below the feed line was introduced and extended as antenna ground to generate broadband circular polarization characteristics. The -10 dB reflection coefficient bandwidth and 3-dB axial-ratio bandwidth of the proposed antenna were measured to be of 47.6 and 27 %, respectively. The 3-dB axial ratio beamwidth of the antenna was 93.5°. The antenna proposed in this work covers multiple application frequency bands including HiperLAN/2 IEEE 802.11a (5.15 - 5.35 GHz / 5.47 - 5.725 GHz) band, WLAN frequency band (5.1 - 5.9 GHz), C-band uplink (5.925 - 6.325 GHz) and part of military application band (4.75 - 4.99 GHz). [ABSTRACT FROM AUTHOR]

The paper presents a triband circular polarized rectangular dielectric resonator antenna. A single coaxial cable feeds the DRA to a double stub strip on the DRA side. A patch strip coupled to the feed assists in widening the bandwidth of the proposed DRA. The degenerate mode pair TE ∂ 11 x and higher- T E ∂ 23 x has been excited to achieve CP and enhance the antenna gain. The higher-order mode has been excited using a low-cost simple excitation mechanism without compromising on the size and shape of the DRA. An impedance bandwidth of 48% with a gain ~6–9 dBic was achieved in all resonance frequencies. Additionally, the AR bandwidth of 5.5%, 4.2%, and 2.76% was obtained at three different frequencies. Note that the proposed DRA exhibits a wide beamwidth of 112o, which is good for better signal reception. A comparison between the measured with simulated results shows that the measured results are matched by the simulated result trends. [ABSTRACT FROM AUTHOR]

A novel broadband circular-polarized array antenna with ultra-wideband low radar cross section (RCS) is proposed. The array is made up of 2 × 2 identically circular-polarized sub-arrays in a chessboard configuration. Furthermore, each sub-array consists of 2 × 2 tightly coupled metasurfacebased elements with linear polarization. For radiation, each element is excited and fed with 90° phase shift between adjacent ones to perform broadband circular-polarized operation. For scattering, destructive phase difference is created in an ultra-wide band for orthogonally polarized incidence due to the anisotropic structure. Thus, a considerable ultra-wideband RCS reduction involving in-band and out-of-band is achieved based on energy cancellation. By this means, broadband circular-polarized radiation and ultra-wideband low RCS performance can be achieved in a synthesized design process. The prototype is fabricated and measured. A good agreement between measured and simulated results verifies the validity of our design method.

This letter presents a low-profile wideband circularly polarized (CP) patch antenna with a single layer of dielectric. An asymmetric inset is incorporated in the antenna structure using two parallel slots, each containing a patch, with a length difference of $\frac{{{\boldsymbol {\lambda }_{\boldsymbol {eff}}}}}{4}$. The length difference leads to a 90° phase difference between the currents on the left- and the right-side patches, causing the antenna to radiate a CP wave. Additionally, a broad bandwidth is achieved because of the additional resonance point generated by a quarter-wave resonance from the asymmetric inset. The proposed antenna achieves a peak gain of 7.4 dBiC and fractional bandwidths of 17.2%, 15.1%, and 13.3%, respectively, for –10 dB $S_{11}$ bandwidth, 3 dB gain bandwidth, and axial-ratio bandwidth with a single-dielectric-layer structure. [ABSTRACT FROM AUTHOR]

The rapid progress in material science and electronic technology is great possibility in designing reconfigurable wireless devices which are frequency tunable, flexible and consume low energy. In this paper, the anisotropic propriety of a new liquid crystal mixture 'GT3-23001ʹ in their nematic phase are exploited for designing tunable circular polarized cross slot patch antenna for WLAN applications. Reconfiguration of frequency response is controlled through an electrical external command. The proposed reconfigurable antenna based on liquid crystal satisfies a continuous frequency tuning of 15.83% with a global bandwidth of around 467.92 MHz (19.5%). to validate this novel mixture of liquid crystal, the simulated results are compared with the measured data and a good agreement is noticed. [ABSTRACT FROM AUTHOR]

The paper presents a triband circular polarized rectangular dielectric resonator antenna. A single coaxial cable feeds the DRA to a double stub strip on the DRA side. A patch strip coupled to the feed assists in widening the bandwidth of the proposed DRA. The degenerate mode pair TE∂11x and higher-TE∂23x has been excited to achieve CP and enhance the antenna gain. The higher-order mode has been excited using a low-cost simple excitation mechanism without compromising on the size and shape of the DRA. An impedance bandwidth of 48% with a gain ~6–9 dBic was achieved in all resonance frequencies. Additionally, the AR bandwidth of 5.5%, 4.2%, and 2.76% was obtained at three different frequencies. Note that the proposed DRA exhibits a wide beamwidth of 112o, which is good for better signal reception. A comparison between the measured with simulated results shows that the measured results are matched by the simulated result trends.

This paper focuses on the investigation of the level powers that can be scavenged from the ambient environment by using corporate feed with dual segment circular polarized antenna array . It will converts the received power to direct current (DC). Being a circular polarized antenna, it has higher inductance per unit area, a good Q-factor and compact capability. The design of corporate-series feed rectenna array is to achieve a high gain antenna and maximize the RF energy received by the rectenna system at ultra low power levels. The entire structure was investigated using a combination of harmonic balance nonlinear analysis and full wave electromagnetic field analysis. The results show that 5.0 dBi gain for circular polarized antenna array can be achieved at frequency 956 MHz. When the input power of 20 dBm fed into the transmitting antenna, the maximum distance for radio frequency (RF) harvesting is 5.32m. The output DC voltage for various values of incident RF power is also presented. There are noticed reasonable agreements between the simulated and measured result and the works concludes that the investigation of RF energy harvesting system was successful.

A kind of circular polarized (CP) stacked dielectric resonator (DR) antenna with wide bandwidth and high gain is presented in this communication. For this design, a two-layer DR with improved performance in bandwidth and gain is used as the basic resonator. By further applying it into a stacked design, two similar modes with adjacent resonant frequencies can be merged together, providing a wide axial ratio bandwidth of more than 20%. The single-feed CP operation is achieved by adopting a coupling cross-slot, which is beneficial for fine-tuning and array forming, as compared to multifeed structures. Two design examples working at different frequency bands and for different senses of CP have been presented to demonstrate the effectiveness of the design concept. [ABSTRACT FROM AUTHOR]

The nanosatellite concept was born from the low‐cost small satellite educational research activities that lead to the nanosatellite revolution. However, in recent years, the development of the nanosatellite is not for just research purpose but commercial opportunities as well. Antenna is very crucial part of the nanosatellite communication system that establishes communication between space to ground. In this paper, an S‐band circular polarized (CP) antenna is presented and investigate the performance compatibility for nanosatellite space mission. The antenna was fabricated on 1.575 mm thick Rogers 5880 substrate material. The measured result shows that the antenna has a −10 dB reflection coefficient bandwidth of 1.64%, 3 dB axial‐ratio bandwidths of 38 MHz and realized gain of around 5.58 dB at the resonant frequency. The antenna was integrated with 2 U nanosatellite structure and investigated the antenna performance. [ABSTRACT FROM AUTHOR]

ABSTRACT This article describes three different types of broad multiband linearly and circularly polarized slot antennas (rectangular, circular, and triangular shaped slot) for millimeter wave wireless communication applications. Proposed antennas consist of a slot radiator on the top metal layer and coupled to a rectangular dielectric resonator above the slot. The conventional microstrip-line-feed is used for different shapes of slot antennas. An high frequency structure simulator, finite element method (FEM)-based, three-dimensional full wave electromagnetic solver simulator by ANSYS was used for the design of the proposed antennas. The final antennas were fabricated and their characteristics were measured. The bandwidth of |S11 | <−10 dB was extended from 19.5 GHz up to 75 GHz. This band covers most of wireless MM-wave applications, fifth Generation mobile and wireless networks, and the WLAN, WPAN, and W-bands. The simulated and measured radiation efficiency, gain, and radiation pattern of the proposed antennas are presented. The average radiation efficiency and gain over the entire operating band are about 60% and 6 dBi, respectively. These antennas are also low profile and low cost. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:976-983, 2017 [ABSTRACT FROM AUTHOR]

This study introduces a new design of dual-band circular polarized (CP) microstrip antenna for ISM band applications (2.45 GHz and 5.8 GHz). The proposed dual-band CP microstrip antenna with compact design has achieved design intention of having return loss of < −10 dB and axial ratio of < 3 dB for both frequencies of 2.45 GHz and 5.8 GHz. The antenna has been successfully designed, fabricated, simulated, and measured and it shows the advantages of good dual-band and CP performances. Thus, the obtained results confirm satisfactory performance and good agreement.

In this paper, a class of integrated metasurface (MS)-based planar antennas are proposed, which are fed by monopoles operating below their fundamental modes. Various interdigitated capacitor (IC) loading schemes for a metallic sheet backed MS are investigated, which provide footprint miniaturization and bandwidth enhancement. A linearly polarized (LP) MS-based antenna, loaded by ICs, provides a 15% impedance bandwidth and a gain higher than 6.67 dBi. The radiation mechanism and resonant frequency dependence were revealed via a dispersion analysis, which serves to explain the working principle of the proposed antenna. Next, a miniaturized antenna with doubly loaded ICs was introduced, achieving an impedance bandwidth of 10%, a gain above 6 dBi, and a more than 30% footprint reduction. A more advanced compact, circularly polarized (CP) MS-based antenna with a compact footprint, and improved 3-dB axial ratio (AR) bandwidth were also presented, by introducing triangular IC and diagonal slot loadings to the MS. It is demonstrated that this antenna achieves an impedance bandwidth of 16%, a gain above 5.5 dBi, and an AR < \text3\ \textdB bandwidth of 10%. Three antenna prototypes were fabricated and measured, with good correspondence between the experimental results and simulation predictions, confirming the proposed design methodologies. These compact and well-performing MS-based antennas have promising potential for applications in modern wideband wireless systems. [ABSTRACT FROM PUBLISHER]

A broadband low-profile, circularly polarized metasurface antenna with a nonuniform aperture is proposed for L band satellite communications. By optimizing the nonuniform geometry, antenna size is minimized and bandwidth is expanded. Characteristic mode analysis (CMA) clearly reveals the dominant modes and stimulated modes for wideband operation. The feeding structure employs a quadrature phase quarter-power divider to excite a collection of orthogonal modes, generating stable circular polarization (CP) radiation and a phase center. Numerous feeds and crossing slots, in conjunction with the metasurface, produce multiple resonances and minimum axial ratio (AR) locations when excited, resulting in a broad impedance and AR response. The low profile nonuniform metasurface CP antenna achieves a 40% −10 dB impedance bandwidth, a 47% 3 dB AR bandwidth, and a peak gain of 8.7 dBic with a compact dimension of 0.67 × 0.67 × 0.06 λ 3. [ABSTRACT FROM AUTHOR]

ABSTRACT In this letter, a low profile circularly polarized wearable antenna with the appearance of a button on clothing for Wi-Fi and WLAN applications is presented. The radiating elements of the antenna are made of copper sheet while a transparent acrylic fiber sheet material is used as substrate and fed by a coaxial line through the ground plane. The proposed antenna is simulated by Ansoft high frequency structure synthesis finite element method-based (HFSS FEM)-based EM simulator and has been optimized to operate within the Wi-Fi and WLAN frequency bands (5250-5850 MHz) with center frequency of 5.25 GHz. A split ring-shaped slot-based frequency selective surface (FSS) is designed to enhance the gain of the proposed antenna. The peak gain of the antenna is found to increase from the conventional antenna gain of 2.1 to 5.1 dBi with the superstrate along with a bandwidth enhancement of 290 MHz. The composite FSS antenna is fabricated and the maximum measured gain of 5.1 dBi matches well with theoretical value. The antenna gets miniaturized around 34% by the slits with its circular polarization characteristic well maintained. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1033-1038, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presented a circle-segmented multiple-input-multiple-output (MIMO) circular polarization (CP) array antenna with dual coupled 90° phased shift for 5.8 GHz Point-to-Point application. Convergence of CP capability within MIMO array antenna is successfully realized by two array of four circular-segmented patch array radiating element that are fed by two RF ports. The MIMO CP array antenna with high gain performance is obtained through the dual coupled 90° phased shift that is connected to each circle-segmented patch. The dual coupled 90° phased shift ensure the E-field of circle-segmented patches function is in 90° phase difference to the initial signals. Similarity between azimuth and elevation plane with axial ratio of 1.9 dB verified the proposed antenna's CP capability. In the mean time, correlation coefficient (ρ) of 1.2015 e − 4, diversity gain (Gapp) of 9.9999, S21 of −45.1 dB show the good isolation quality of the antenna in MIMO structure. The gain of 14.6 dB for each port is also recorded. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:809-814, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel single feed of the truncated edge circular polarized array antenna for 2.4 GHz applications with high gain is analyzed and proposed. The presented circular polarized antenna is comprised of four patches as its radiating elements and fed by a single coaxial connector at the ground layer. Dimension-wise, the proposed antenna is designed with compact size of 56 × 69 × 1.6 mm3. It is notified that 45° of patches' truncated edge, 45 mm element spacing of Y-axis, and 39.5 mm element spacing of X-axis collectively contribute to the circular polarization capability. The prototype of the antenna has a right-hand circular polarization with an axial ratio of 2.019 in particular of 2.4 GHz. Additionally, the similarity patterns of E-plane and H-plane of the antenna prove its circular polarization capability. Further, the proposed antenna seems to have an omnidirectional pattern eventhough using a full ground plane and improved the effective coverage angle. With the measured gain of 5.35 dB and the reflection coefficient of −14.16 dB, the proposed antenna has big potential for Wi-Fi and biomedical application. The antenna prototype performance is verified, and the experimental result is presented and discussed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1337-1344, 2014 [ABSTRACT FROM AUTHOR]

A wideband circularly polarized (CP) slot antenna array is presented by employing cavity-backed CP multi-feed slot antenna as the element. The antenna element consists of four microstrip-fed circular stubs that excite the circular slot to generate circular polarization, a circular back cavity and a separate corporate feed network layer. The measured 3-dB axial-ratio (AR) bandwidth of the element is 38.6% (4.6-6.8 GHz) in which the reflection coefficient (|S11|) is below −10 dB. The investigation is extended to a 2 × 2 antenna array by using sequentially rotated technique. Wilkinson power dividers are applied to design the feed network of the array. The fabricated antenna array can provide a 1-dB AR bandwidth of 55.7% (4.4-7.8 GHz). In the 1-dB AR bandwidth, the |S11| is below −10 dB and the gain is more than 10.0 dBic. The 3-dB gain bandwidth is about 40.0% (4.8-7.2 GHz) with the maximum gain 15.1 dBic. [ABSTRACT FROM AUTHOR]

A simple technique to design circular polarized microstrip patch antenna with broad bandwidth is presented. Two different feed mechanisms are designed to excite the dual orthogonal linearly polarized modes from a single radiating patch for the operated frequency band at around 2.4 GHz. One of the two modes is excited by an L-shaped probe, and the other is excited by an H-shaped aperture. The proposed design has a very simple antenna structure with an impedance bandwidth of 75.92% and a 3-dB axial ratio (AR) bandwidth of 49.89%. The −3 dB gain bandwidth is about 32%, and the peak gain is 8.42 dBi at around 2.4 GHz. Measured results of the fabricated antenna prototypes are also carried out to verify the simulation analysis. [ABSTRACT FROM AUTHOR]

A novel design of a circular polarized antenna for multiband GPS receivers is presented. The design employs the concept of multistacked patches fed through a single coaxial probe. Three patches being stacked together with a slit and symmetry I-slot are used to achieve triple operating frequency bands for GPS including L1 (1.575 GHz), L2 (1.227 GHz) and L5 (1.176 GHz). The proposed antenna has achieved a bandwidth of 2.0%, 1.5%, and 1.7% at GPS L1, L2, and L5 bands, respectively. It exhibits a minimum axial ratio of 0.51 dB with broad beamwidth in the upper hemisphere required for the GPS applications. The design of the proposed antenna is verified in the experiment. In addition, a detailed analysis has been carried out to study the effects of different geometrical parameters on the performance of the antenna. [ABSTRACT FROM PUBLISHER]

This study introduces a new design of dual-band circular polarized (CP) microstrip antenna for ISM band applications (2.45 GHz and 5.8 GHz). The proposed dual-band CP microstrip antenna with compact design has achieved design intention of having return loss of < --10 dB and axial ratio of < 3 dB for both frequencies of 2.45 GHz and 5.8 GHz. The antenna has been successfully designed, fabricated, simulated, and measured and it shows the advantages of good dual-band and CP performances. Thus, the obtained results confirm satisfactory performance and good agreement. [ABSTRACT FROM AUTHOR]

This paper presents a dual-band circular polarized (CP) hybrid dielectric resonator antenna (HDRA) with gain enhancement. The fundamental TE 111 mode and high-order TE 113 mode are excited by the orthogonal CPs in the two frequency bands. This is achieved by cutting four corners along the DRA diagonal and adding a metal strip on the corner. The DRA design procedure is presented to verify its operations. The gain improvement is achieved by loading the water on the top of DRA. This leads to a 1.32 dB improvement on the upper band and have no impact on the lower band. The proposed DRA is fabricated and measured. The results verify its dual-band CP operation at 1.58 GHz (left-hand) and 2.40 GHz (right-band). Two bandwidths of the lower band and upper bands are 20.52% and 21.72%, respectively. The gain improvement is verified from the measurement on both states. The proposed HDRA can be applied for the dual-function communications such as GPS and WLAN. [ABSTRACT FROM AUTHOR]

For a given feed position, newly derived equations are used to determine the dimensions of a circular-polarized (CP) nearly square patch antenna. It is also shown that for a feed offset from one corner of the patch, the perturbation segment (ΔS) is increased, thereby reducing the effect of manufacturing errors. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 406–410, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21001 [ABSTRACT FROM AUTHOR]