Simple Antenna Structure Research Articles

LTE MIMO Closed Slot Antenna System for Laptops With a Metal Cover

This paper presents an LTE MIMO closed slot antenna system for laptops with a metal cover. Its main and auxiliary antennas have the same structure that measures 130 × 3 mm 2 . They are configured in a manner of reflection symmetry on the display metallic ground plane and are 5 mm away from the hinge. The distance between the two antennas is 20 mm, and the profile height of the MIMO antenna system is only 3 mm. This LTE closed slot antenna is excited by an exciter of 30 × 3 mm 2 to cover the LTE eight-band operation (LTE700/GSM850/900/1800/1900/UMTS/LTE2300/2500). The exciter is a simple planar inverted-F antenna (PIFA) structure loaded with reactive matching elements, which can enhance the impedance matching in the desired frequency bands. This LTE MIMO closed slot antenna system has good isolation of at least 16 dB without adding any additional isolation elements. The measured antenna efficiency of the MIMO antenna system is larger than 40% in the low-frequency band and 50% in the high-frequency band, meeting the practical application requirements.

A Dual-Broadband Dual-Polarized Fylfot-Shaped Antenna for Mobile Base Stations Using MIMO Over-Lapped Antenna Subarrays

This paper proposes a novel design of a dual-broadband dual-polarized antenna for mobile communication base stations. The proposed antenna is Fylfot-shaped and covers 0.7–0.96 and 1.7–2.7 GHz simultaneously (with S11 ≤ −10 dB), which are the two common frequency bands for mobile communication systems. Three resonant frequencies are produced in the proposed design where two of them are independently controlled to achieve the dual-broadband performance. A prototype of the proposed antenna has been developed and tested. The results demonstrate that the antenna has high isolation between its ports, high polarization purity, and stable radiation patterns across both the frequency bands. A new linear array is proposed and implemented. Unlike reported dual-band base station antenna arrays, the proposed array uses a novel technique of two MIMO overlapped subarrays with shared radiating antenna elements. The overlapped subarrays have excellent frequency diversity performance with low envelope correlation coefficients. The array has been found to have the same performance as a standard conventional base station antenna but with 25% less number of antenna elements, which leads to a smaller size and lower cost. The simple antenna structure and the novel smart MIMO overlapped antenna subarrays technique give the design the privilege to be an ideal candidate for a low-cost directive base station antenna.

Pattern synthesis for equal-gain coverage in air-to-ground communication

In this article, a new strategy for high-quality and wide-coverage air-to-ground communication is proposed by using pattern synthesis method. The cosecant pattern for equal-gain coverage is synthesized using two switchable patterns, which are provided by switchable feeding networks and a ten-element airborne microstrip antenna array. The merits of the proposed strategy include two folds: first, the antenna array and feeding network are easy to design and with low cost, no need to use beam steering method. Second, the maximum available gain in the required cosecant coverage is achieved by the proposed strategy, providing sufficient path loss margin. We have simulated and fabricated the array prototype, and measured results have proved our idea to achieve equal-gain coverage with a relatively simple antenna structure. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:750–753, 2017

Half-Loop Frame Antenna for the LTE Metal-Casing Tablet Device

The use of metal casing is attractive to achieve robustness of modern slim tablet devices. The metal casing includes the metal back cover and the metal frame around the edges thereof. For such metal-casing tablet devices, the frame antenna that uses a part of the metal frame as an antenna’s radiator is promising to achieve wide bandwidths for mobile communications. In this paper, the frame antenna based on the simple half-loop antenna structure to cover the long-term evolution 746–960 and 1710–2690 MHz bands is presented. The half-loop structure for the frame antenna is easy for manufacturing and increases the robustness of the metal casing. The dual-wideband operation of the half-loop frame antenna is obtained by using an elevated feed network supported by a thin feed substrate. The measured antenna efficiencies are, respectively, 45%–69% and 60%–83% in the low and high bands. By selecting different feed circuits, the antenna’s low band can also be shifted from 746–960 MHz to lower frequencies such as 698–840 MHz, with the antenna’s high-band coverage very slightly varied. The working principle of the antenna with the elevated feed network is discussed. The antenna is also fabricated and tested, and experimental results are presented.

Design of Dual-band Coplanar Dipole Antenna for LTE Applications

In this paper, we propose a simple structure of coplanar dipole antenna with a tuning stub. The antenna which exhibits dual band is designed and fabricated respectively. The influences of stub length parameter of coplanar dipole antennas on the resonant frequency, return loss and bandwidth are also discussed. We use IE3D software to design coplanar dipole antennas and choose the better stub length parameter to manufacture coplanar dipole antenna. The proposed antenna here with the size of 150mm×30mm×1.6mm possesses the dual-band characteristics, 692MHz-832MHz and 1451MHz-1926MHz. The fabricated antenna is suitable for long term evolution (LTE) applications at 700MHz and 1800MHz.

Dual‐band antenna with combination of printed dipole and aperture coupled rectangular patch antenna

ABSTRACTIn this letter, a novel simple structure of dual band microstrip antenna is presented. The antenna configuration is composed of two antennas that one of these antennas is printed dipole antenna and the other one is 1 × 2 aperture coupled rectangular patch antenna array. The parameter design of each antenna, which resonating as independent antennas, is designed based on their resonating frequency. The prototype of this antenna is fabricated and measured. The measured results show a good S‐parameter, reasonable gain, and stable omni‐like radiation patterns in two working frequency bands. According to measured results, the proposed dual‐ band antenna can cover 2.03–2.90 GHz, and 4.80–5.09 GHz, which are allocated for wireless applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:186–188, 2017

A compact printed monopole antenna with enhanced bandwidth and variable dual band notch for UWB applications

This article presents a compact, enhanced bandwidth, and variable dual band notched printed monopole antenna for ultra wideband (UWB) applications. By inserting a simple inverted L-shaped slot in the ground plane and modifying the lower edge of the patch, wider bandwidth with usable fractional bandwidth of 139.2% (3.1–17.3 GHz) is achieved whereas two inverted U-shaped slots in the corner modified patch are embedded to realize two notch bands exactly at WiMAX (3.25–3.75 GHz) and WLAN (5.1–5.9 GHz). A precise design formula is also proposed to calculate the length of the slots. The proposed simple antenna structure with a 50 Ω feed line has been obtained within a small size of 0.11λ × 0.19λ. The simulated results are validated using measured results to show potentiality of the proposed antenna structure in UWB applications.

A Comparative Analysis of Asymmetrical U-Slot and Substrate Integrated Waveguide Fed Microstrip Patch Antenna

paper shows a comparative study of Multi U-shaped slot antenna with the substrate integrated waveguide(SIW) fed patch antenna. By cutting four asymmetrical U-slots, we can make U-shaped patch antenna. Advantages of this structure are the simple feed, single layer structure, simple structure of antenna, one more degree of freedom can be achieved by the asymmetry of U-slot arm. The design guideline for the proposed antenna is given and the acceptability of the design is verified by other scenarios. When we create two different frequency bands with distinct polarization, two longitudinal and transverse slots on broad wall of SIW of other antenna is responsible for it. For reducing the cross polarization level of antenna, frequency selective surface (FSS) is placed on top of the microstip patches. For getting the wider impedance bandwidth, we do close the resonance frequencies of the patch and slot to each other. Efficiency of the antenna can be increases by SIW feeding network.

Wideband dipole antenna using multiple‐mode resonator for long‐term evolution application

A coplanar waveguide fed wideband dipole antenna using a multiple-mode resonator is proposed and developed. A simple dipole antenna structure is investigated for its wideband radiation performance by virtue of its single, double, triple and quadruplet resonant modes. Later, a metallic reflector is properly installed in order to provide a unidirectional radiation pattern as demanded for the long-term evolution (LTE) application. In the design, a quadruplet-mode wideband dipole antenna is explored to cover the LTE operation band with a 10 dB fractional bandwidth of 46.8%. Finally, an antenna prototype is fabricated and tested to experimentally verify the expected wideband property and predicted results.

Simple antenna structure enabling the simultaneous excitation of two different polarisation and radiation modes

A simple antenna structure able to simultaneously generate two different polarisation and radiation modes is proposed. In addition to a good impedance matching all over multiple bands, antennas based on the proposed geometry can exhibit a linearly polarised omnidirectional radiation pattern at lower frequencies, allowing the communication in any azimuthal direction, and a circularly polarised directive diagram at higher frequencies that enables links for satellite-based applications. These characteristics together with a low-profile, a light weight and a robust and easy-to-realise structure make the antenna an effective candidate for integration into vehicles. The antenna multimode radiation mechanism is explained in detail. In order to demonstrate its effectiveness, the proposed structure is applied to the design of two different antennas for practical applications. The performances of these antennas are assessed by means of numerical simulations and validated through experimental measurements.

A Low Frequency Helical Antenna for Sub Surface Communication

The purpose of this paper is to develop a simple antenna structure of limited dimension suitable for low frequency and under ground communication. The closed wound helical antenna of length small compared to wavelength is found to be a better radiator compared to a linear antenna of same length. Field expressions for both dissipative and non dissipative media are calculated and tabulated. A chart is provided to study the reflection effect and a curve is plotted showing the relative strength of helical antenna with respect to the linear antenna. The assumption of uniform earth's characteristic is made through out the analysis.

Broadband circularly polarized patch antenna with gap-coupled feed and resistor loading

A broadband circularly polarized patch antenna with suspended structure is proposed. The suspended patch has a bow-tie structure and a gap-coupled feed. By connecting a resistor load to another gap-coupled feed port at the opposite position, a wide impedance and axial ratio AR bandwidths are obtained. The proposed design has a very simple antenna structure with an impedance bandwidth of 44.5% and a 3-dB AR bandwidth of 33.8%, respectively. The results show that the bandwidth of the patch antenna is successfully broadened using the suspended configuration, gap-coupled feed, and resistor loading. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:587-593, 2014.

DESIGN OF DUAL-FEED DUAL-POLARIZED MICROSTRIP ANTENNA WITH HIGH ISOLATION AND LOW CROSS POLARIZATION

A broadband dual-feed dual-polarized microstrip antenna with low cross polarization and high isolation is presented. The dual- orthogonal linearly polarized mode is excited by two difierent feed mechanisms from a single circular radiating patch. One of the two modes is excited by a pair of L-shaped probes with a 180 - phase difierences, and the other is excited by an H-shaped aperture. The proposed design has a very simple antenna structure with a wide input impedance bandwidth (23.25% for Port 1 and 35% for Port 2) and also its two input port isolation is found to be as low as i40dB. Measured results of the fabricated antenna prototypes are also carried out to verify the simulation analysis.

Broadband Circularly Polarized Microstrip Antenna Using L-Shaped Probe and H-shaped Aperture-Coupling

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.

Improved Planar Wideband Antenna Element and Its Usage in a Mobile MIMO System

A simple antenna structure for a multiple-input-multiple-output (MIMO) system in a mobile terminal with spatial diversity is presented. A single antenna element consists of a combination of an electric dipole and a square magnetic slot. The studies with a single quasi-complementary antenna element show that the electric dipole and the square-shaped magnetic slot are partially compensating the effect of the electric conductor closely spaced to the electric dipole (0.0037-0.01λ) . Simulations also show that by scaling antenna structure, a 0.7-2.1-GHz frequency bandwidth can be achieved. The measured -6-dB impedance bandwidth of the MIMO antenna prototype is from 2.0 to 5.6 GHz, corresponding to a 95% relative bandwidth. The measured <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> is less than - 19 dB within the - 6-dB impedance bandwidth. The average measured total efficiency at the aforementioned bandwidth is - 0.85 dB. The measured radiation patterns are presented at 2 and 5 GHz with a maximum total gain of 2.8 and 5.7 dBi, respectively. The measured envelope correlation of the MIMO antenna is less than 0.04 with 90% MIMO efficiency within the -6-dB impedance bandwidth.

Isosceles Triangular Slot Antenna for Broadband Dual Polarization Applications

An isosceles triangular slot antenna is proposed for broadband dual polarization applications. The proposed design has a very simple antenna structure and a wide impedance bandwidth ( ~ 19.7% for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | and |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sub> | les -10 dB) which can cover the 5 ~ 6 GHz frequency band for Wireless Local Area Network applications. Good isolation between the two input ports |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | and low cross-polarization radiation level (<-15 dB) are achieved, and the antenna gains radiated from the two diversity ports are almost equal and stable over the entire operating band. These features make the proposed antenna very attractive in broadband dual polarization applications.

Simulation of MIMO channel capacity with antenna polarization diversity

A simulation study of the channel capacity of a multiple-input multiple-output (MIMO) antenna system exploiting multiple polarizations is carried out. We focus on a simple yet realistic trimonopole antenna structure, taking into account all the mutual coupling and casing effects using the computational electromagnetics solver-numerical electromagnetics code. Simulation results show that, with a special transmit geometry, using the collocated trimonopole antennas at a size-constrained receiver can offer channel capacity that approaches the capacity of an uncorrelated MIMO Rayleigh channel. In addition, it is shown that the capacity increase is mainly attributed to polarization diversity instead of pattern diversity. Furthermore, we find that the mutual coupling and casing effects in the trimonopole system can actually provide a large capacity increase with less constraint on the antenna configurations than the idealized tridipole system.

Dual-frequency operation of bow-tie microstrip antenna

Characteristics of a single-feed dual-frequency bow-tie microstrip antenna are studied. By using the variation method, simple formulas for resonant frequencies of the bow-tie microstrip antenna are derived. It is shown that the dual-frequency ratio can be controlled easily by choosing the parameters of the antenna. This design gives compact antenna size and simple antenna structure. Experimental results are presented, verifying the validity of the design.

Wideband folded‐patch antennas fed by L‐shaped probe

AbstractSimple folded‐patch antennas fed by an L‐shape probe are designed and studied experimentally. This simple antenna structure with thick air substrate attains a projection‐length reduction of about 30% with reference to the conventional half‐wave patch antenna. This antenna attains an impedance bandwidth of 35% and a gain of 6 dBi. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 352–355, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20821

Correlation of antenna charging and gate oxide reliability

Antenna structures are commonly used to study charging, and the resultant metal–oxide–semiconductor gate oxide damage, from plasma processing. Degradation of various device parameters, such as gate leakage and threshold voltage, have been correlated with high levels of charging. However, there has been little work done to correlate charging with reduced device reliability. In this study, we use antenna structures and accelerated life testing of application specific integrated circuit devices on the same wafers to show that oxide damage from charging measured by antennas does not necessarily correlate with reliability degradation. Depending on how the antenna is designed, the measured oxide damage results from a combination of process-induced charging and initial gate oxide quality. When initial oxide quality is high, then charging which does not degrade oxide reliability can occur. However, for initially defective oxide, the same process-induced charging can degrade reliability. As shown in this study, the key to distinguishing between the two is in the antenna design. Failures of simple antenna structures having a large antenna area ratio and small gate oxide area did not correlate with degraded oxide reliability. However, failures of antenna test structures having a relatively small antenna area ratio and a relatively large gate oxide area did correlate with reliability, probably by highlighting pre-existing defects in the gate oxide which induced the early reliability failures. Together, these two types of antenna structures can help differentiate between excessive plasma damage and intrinsic weakness in the gate oxide.