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Due to the specificity of the application, directional hand-held antennas for outdoor use are subject to mechanical damage. Therefore, when choosing directional hand-held antennas for outdoor use, in addition to considering electrical and electromagnetic characteristics of antennas, special attention should also be paid to the mechanical characteristics of antennas. Quad antennas, although they have excellent electrical and electromagnetic characteristics due to the complexity of their construction, and unsatisfactory mechanical characteristics have not found application as hand-held antennas for outdoor use. This paper presents a new idea in the design and construction of a quad antenna that has reinforced mechanical characteristics. This paper presents the design of compact handheld quad antennas suitable for outdoor mobile applications. The antennas were tested in practice, they were subjected to various mechanical stresses. Impressive mechanical strength and compactness of the antenna have been achieved. The numerical electromagnetics code software 4nec2 is used to design, analyze and optimize the presented antennas. The presented antennas operate at a frequency of 446 MHz. The voltage standing wave ratio (VSWR) of all presented antennas was measured by a vector analyzer and is better than 1.5. There was a small deviation between simulated and measured results. Possible reasons for this discrepancy are listed and commented on.

This paper presents the design of a compact double-loop sub-6-GHz dual-band MIMO quad-antenna system for 5G laptops. To meet the market demand for laptops with a high screen-to-body ratio, the sub-6-GHz dual-band MIMO quad-antenna system is realized to have a low-profile height of only 3 mm. To make the MIMO quad-antenna system suitable for laptops with a narrow bezel, the four antenna elements are printed on the same FR4 substrate, which is mounted on the upper edge of and coplanar with the display ground plane of a laptop. The four antenna elements have the same double shorted loop structure and the same size of $15\times $ 3 mm2. In the loop structure, a meandered path is embedded in one of the two shorted-end sections, and a series chip capacitor is embedded in the other. The low-frequency resonance mode can be adjusted by varying the meandered path, and the high-frequency resonance mode can be tuned using the meandered path and the series chip capacitor. The four antenna elements are aligned in the same direction with an end-to-end gap of 5 mm so that satisfactory isolation can be achieved without any additional isolation elements. The MIMO quad-antenna system, although measuring only $75\times $ 3 mm2 with the three gaps included, can cover 3400–3800 and 4800–5000 MHz for 5G dual-band operations. The measured isolations between the four antenna elements are larger than 10 dB, the envelope correlation coefficient (ECC) values calculated from the measured radiation patterns are all below 0.27, and the measured radiation efficiencies of all four antenna elements are over 42%.

Due to the confined space in which they are typically used, directional ultra– highfrequency (UHF) antennas for indoor use should be particularly compact. Also, due to the frequent need to manually direct (rotate) the antenna, it must be relatively light with good mechanical characteristics. By simultaneously considering the compactness of various types of antennas, weight, electrical, electromagnetic, mechanical, and radiation properties of antennas, several types of antennas are particularly suitable for directional UHF amateur radio antennas for indoor use. In this sense, various types of quad antennas stand out. Despite the fact that Quad antennas have excellent performance and electromagnetic properties, because of their complicated and slow construction, they are not popular among radio amateurs. This article presents a new idea in the selection of materials for the construction and construction solution of Quad antennas for indoor use. The presented construction solution simultaneously ensures a simple construction but with significantly reinforced mechanical characteristics compared to the typical constructions of Quad antennas. This article presents the design of compact UHF Quad antennas suitable for indoor applications. The presented antennas are dual stacked Quad antennas. Impedance matching was achieved by coaxial cables. The antennas are built for the frequency of 446 MHz, the so–called personal mobile radio (PMR). Both antennas were tested for mechanical stress typical for their use such us moving and rotating the antennas. After prolonged use, no damage, deformation, or weakening of the joints was observed. Numerical calculations and optimizations of the presented antennas were performed using 4nec2 software. The measured voltage standing wave ratio (VSWR) of the presented antennas is below 1.5.

This paper presents an antenna system for scavenging ambient microwave energy. This antenna model consists of four 2×2 rectangular patch antenna arrays placed in a quad shape geometry, designed at 2.4 GHz. It provides a coverage of 360 degrees in azimuthal plane for capturing energy, thus, increasing the energy for harvesting. Maximum gain achieved by presented model is 7 dBi. Such a structure enables to either connect the rectifiers directly to each of the faces or combining RF power from all faces and connect to a single rectifier. Simulations for the antenna model were performed using ANSYS HFSS.

In the design of latest wireless devices more emphasis has been put on the miniaturization of antennas accompanying efficiency. Patch antennas have found a huge scope in this evolving era of technology. The high data rate and least fading requirement has paved the way for the MIMO antenna technology. This paper presents four element patch antenna which operates in three frequency bands between 2GHz and 6 GHz. The four elements are placed orthogonally with respect to each other's orientation on the square space giving it a quad antenna configuration. The design proposed takes into account the effect of spatial and polarization diversity technique for common return loss and good isolation between different ports. The result shows VSWR of less than 2 dB and has more than 10dB of isolation is obtained between any of the ports of respective antenna elements.

This letter presents a wideband/multiband quad-antenna system for 4G/5G/GPS metal-frame mobile phones. The quad-antenna system has two kinds of antenna elements and four antenna elements. The merit of the proposed antenna system is that a quad-antenna system is achieved under the condition of metal frame, and without using any decoupling structure, the desired bands for 4G/5G/GPS are covered. A prototype was fabricated and measured. For the first kind of antenna elements (including two antenna elements), the bands of 698–960, 1710–2690, and 3400–3600 MHz are covered, and the LTE700/GSM850/GSM900/GSM1800/GSM1900/LTE2300/LTE2500/3.5 GHz bands all are covered. For the second kind of antenna elements (including two antenna elements), the bands of 1440–2690 and 3400–3600 MHz are covered, and the GPS, GSM1800/GSM1900/LTE2300/LTE2500/3.5 GHz bands are covered. The measured isolations are bigger than 10 dB. The measured efficiencies are bigger than 40% at all the working bands. The measured envelope correlation coefficients are very suitable for multiple-input--multiple-output (MIMO) communication systems.

this paper presents the design and fabrication of a Planar Bi-Quad Antenna operating at 2. 45GHz. The modeling and simulation of the antenna is done using the CST Studio Suite (Student Edition) and the testing of the fabricated antenna is done using the Antenna Measurement System Kit (AMS Kit) developed by Akademica. This antenna shows improved bandwidth and characteristics over conventional wired Bi-quad antennas. Various antenna parameters such as Radiation Pattern, Directivity, VSWR, S11, etc. are calculated. A close agreement is found between the simulation and the experimental results.

To increase the integration level of multiple-input multiple-output (MIMO) antennas for accommodating the size-limited environment in fifth-generation (5G) smartphones, a wideband integrated quad-antenna building block is proposed in this paper. Specifically, the integrated yet decoupled quad-antenna building block is fulfilled by the combination of two wideband decoupling techniques between back-to-back and face-to-face open-slot antennas. For validation, an 8×8 MIMO system, constituted by two sets of quad-antenna building blocks, is simulated, fabricated, and measured. Both the simulated and measured results show that, the 8×8 MIMO system can offer an isolation of better than 10 dB and total efficiency of large than 41.4% across 3.3-5.0 GHz, which is a promising candidate for the future highly-integrated wideband 5G smartphone antennas.

Quad helical antenna is designed for Multiple Inputs Multiple Outputs (MIMO) application in the 700 MHz Europe 2020 allocated band for wireless communications. The quad printed helical antenna with four collocated independent ports has S11

A simple method for designing a quad antenna element Ultra Wideband (UWB) Multiple Input Multiple Output (MIMO) antenna is presented in this work .The presented quadelement UWBMIMO antenna is printed on substrate FR4having the dimension of 110×119×1.5 mm3.The four elements of antenna are orthogonally positioned with each other for improving isolation. For achieving further isolation between elements of antenna, a metallic parasitic strip having plus shape is printed in ground. The proposed antenna design has obtainedS 11

A millimeter-wave (mm-Wave) dual-feed square loop antenna is presented in this paper for 5G communications. It synthesizes identical far-field radiation patterns as a conventional single-feed square loop antenna. The dual-feed antenna (DFA) also simplifies or even eliminates the lossy power-combining network between the transmitter and antenna, achieving direct on-antenna power combining. The proposed antenna concept significantly improves the total radiated power and power efficiency of a wireless transmitter, particularly useful for 5G transmitters that normally require large output power to compensate the high mm-Wave path loss. Compared with antenna-array-based spatial power combining, the DFA only requires a single-antenna footprint and maintains the single-element beamwidth, ideal for mobile 5G communications. The dual-feed square loop antenna is designed and characterized at two potential 5G bands, i.e., 38.5 and 73.5 GHz. Conventional single-feed square loop antennas are implemented as reference designs. Closely matched antenna characteristics are achieved in measurement between the proposed DFA and conventional single-feed antenna. The dual-feed square loop antenna has measured broadside gain of 2.9 and 3 dBi, and fractional bandwidth of 13% and 14%, at 38.5 and 73.5 GHz, respectively. High-speed modulation test is also performed. A 4.3% error vector magnitude (EVM) with a −33.2-dBc adjacent channel leakage ratio (ACLR) for 6-Gb/s 64QAM is achieved at 38.5 GHz, and a 5.6% EVM with a −33.4-dBc ACLR for 6-Gb/s 64QAM is measured at 73.5 GHz, which demonstrates the viability of the proposed DFA for high-speed and complex modulations required by 5G communications.

This paper presents the integrated amateur band and ultra-wide band (UWB) monopole antenna with integrated multiple band–notched characteristics. It is designed for avoiding the potential i...

In this paper, a dual-band high frequency (HF) and ultra-high frequency (UHF) radio-frequency identification (RFID) tag antenna is presented that operates in the 13.56 MHz band as well as in the 920 MHz band. A spiral coil along the edges of the antenna substrate is designed to handle the HF band, and a novel meander open complementary split ring resonator (MOCSRR) dipole antenna is utilized to generate the UHF band. The dual-band antenna is supported by a single-feeding port for mono-chip RFID applications. The antenna is fabricated using an FR4 substrate to verify theoretical and simulation designs, and it has compact dimensions of 80 mm × 40 mm × 0.8 mm. The proposed antenna also has an omnidirectional characteristic with a gain of approximately 1 dBi.

The upcoming standards of wireless communications result in additional and more stringent requirements for antennas in mobile phones. In this paper, we present a frequency-reconfigurable antenna that could potentially be suited for future mobile devices. Frequency reconfigurability is achieved through a cluster of mutually coupled antenna elements that is excited with frequency-dependent weights using a multichannel transceiver. We report a mobile handset antenna cluster measuring 15 $\times $ 15 $\times $ 1.6 mm3 that covers the frequency bands of 1.7–2.7, 3.3–4.5, and 5.475–6.425 GHz with an antenna efficiency better than 90%. The operation of the antenna cluster is experimentally verified by feeding all the antenna elements with proper weights using tailor-made power splitters that represent a multichannel transceiver with adjustable amplitude and phase in each branch. The results obtained with the feed networks suggest the feasibility of the reconfigurability concept and pave way for codesign of the antenna and the transceiver.

The functionality of a dual-band frequency-reconfigurable antenna based on a microstrip patch is extended toward independent tuning of its two operational bands. The antenna has distinct monopolar and broadside radiation patterns at its lower and upper bands, respectively, and a previous realization only allowed simultaneous tuning of the two bands. In this paper, a more sophisticated bias scheme with two DC bias voltages and four varactors is introduced to extend the principle toward independent control of the resonance frequencies of the two bands. An antenna prototype has been designed, fabricated, and validated with experiments. The results demonstrate that the antenna achieves independent relative tuning ranges of about 11% at both frequency bands.

This paper presents a narrow band frequency reconfigurable antenna for global navigation systems. Proposed frequency tunable antenna operates for GLONASS (1.601 GHz), GPS (1.575 GHz) and COMPASS (1.561 GHz) navigational systems. Antenna design consists of rectangular patches, two pin-diode switches, feed network, biasing circuitry and supply lines to make antenna operational for three frequency bands. Antenna is simulated and optimized using CST—Computer simulation technology and is fabricated on Roger RO4350b substrate. The demonstrated antenna along with being frequency agile possess essential performance characteristics like high gain, stable radiation patterns and good radiation efficiency for all three frequency bands, making it prospective choice for wireless navigational systems.

In this paper, a novel compact ultra-wideband (UWB) antenna with a quad band-notched function using S-SCRLHs (splited simplified composite right/left-handed) resonator is presented. The S-SCRLHs resonator, which exhibits quadruple resonance, is realized by coupling double S-SCRLH resonator. Then, the S-SCRLHs resonator is integrated into a UWB antenna consisting of modified circular patch. The proposed UWB antenna operates under the frequency range of 3.0–10.7 GHz. This proposed antenna displays a VSWR

In this paper, a novel polarization and frequency reconfigurable microstrip patch antenna which can switch between vertical and horizontal linear polarizations, left hand and right hand circular polarizations at two WLAN frequencies is presented. The orthogonal linear polarizations are achieved by a square microstrip patch antenna fed by two ports on adjacent sides. By introducing corner truncated perturbation on opposite corners of right diagonal of a square patch, orthogonal circular polarizations are achieved. By controlling the bias voltage of two PIN diodes loaded at perturbed corners, a single structure can achieve quad polarization states. Furthermore, by superimposing a square ring slot into the corner truncated square patch and incorporating four PIN diodes into the square ring slot, quad polarization are achieved at dual frequencies. Simulated and measured results indicate that the antenna can achieve quad polarization at two WLAN bands (5.15–5.35 GHz) and (5.75–5.85 GHz). The proposed antenna is simple, has low profile and can be scaled easily for other frequencies.

Full-dimensional multiple-input multiple-output (FD-MIMO) systems, whereby each base station is equipped with a uniformly spaced rectangular antenna array (URA), provides a practical means of realizing massive MIMO systems. However, the spectral efficiency of URA is considerably lower than that of its uniformly spaced linear array counterpart having the same number of antenna elements. In this paper, we first introduce a discrete angular resolution metric for quantifying the low resolution of URA in the antenna-elevation domain. This motivates us to propose a novel antenna device design, referred to as the structured non-uniformly spaced rectangular array (NURA), in which the antenna elements are non-uniformly distributed in the elevation-angle domain. Specifically, we conceive a structured NURA device for which the nonuniform distribution of the elevation-domain antenna elements is controlled by a single parameter. The design of the optimally structured NURA for the given nonlinear antenna-element-positioning function then becomes a single parameter optimization, namely, that of maximizing the spectral efficiency of the FD-MIMO system, which can be solved efficiently. Our simulation results demonstrate that our structured NURA design significantly outperforms the standard URA in terms of achievable spectral efficiency. Our proposed structured NURA design therefore offers an effective practical framework for enhancing the achievable performance of FD-MIMO systems.

This article reports on the design and development of a novel sharedaperture antenna that is set at the widely separated L5 and S bands for navigation satellite systems with its concentric phase centers located at the two bands. The design of the radiating element and its performance is also detailed as well as the design of the critical sections, namely, the square-coaxialline and waveguide feed networks, in view of multipaction and average power handling capability. An innovative method of implementing a sequential rotation scheme for improving the array cross-polarization isolation is discussed, and, subsequently, this article also presents and compares the measured and analyzed results of the array antenna set at the L5 and S bands. After data analysis, it was found that the in-orbit test results of the antenna well agreed with its measured results acquired at the ground level.

A novel compact microstrip-fed UWB antenna with quad notched band is proposed. The antenna consists of a rectangular radiating patch with a half circle, a tapered microstrip feed-line, and a semi-elliptical ground plane. With a pair of L-shaped slots, complementary co-directional SRR and a pair of C-shaped stubs, four notched bands are created to prevent interference from WiMAX/lower WLAN/higher WLAN/X-band. Experimental results show that the designed antenna, with compact size of 20 × 30 mm2, has an ultrawide band (VSWR

In this paper, a planar directional beam-switchable antenna with four orthogonal beam directions is proposed. The proposed antenna is designed with two crossed active elements and two parasitic elements for each direction. The design methodology is described on the basis of the Yagi-Uda method for the active and parasitic elements, respectively. By adjusting the effective electric lengths of the parasitic elements, the roles of a director and a reflector are exchanged with each other. The planar four-way beam-switchable Yagi-Uda antenna is implemented. From the experimental results. The proposed design method is verified for orthogonal radiation beam switching.

A reconfigurable loop antenna with two parasitic grounded strips for modern smartphone devices is presented in this paper. The most essential merit of this proposed reconfigurable antenna is that it can keep the intactness of the outer metal rim. In addition, it can generate multiantenna modes. The outer metal rim generates three loop modes and the inner parasite grounded strips can provide two monopole modes. By merging these two types of antenna modes, it can offer two wide bandwidths to cover GSM850/900, DCS/PCS/UMTS2100, and LTE2300/2500 operations with a compact antenna size of 945 mm2. The detailed operating principles and design considerations of this proposed reconfigurable antenna are described. In order to validate this proposed antenna, it was fabricated and tested. The measured antenna efficiencies and gains are satisfied with the requirements for the modern communication devices.

In this letter, a W-band multipolarized monopulse Cassegrain antenna is proposed, in which a phased dual-polarized microstrip patch quad is employed to feed the hyperbolic subreflector. Due to the more even polarization distribution on the aperture of the quad, the high aperture efficiency of the Cassegrain antenna is achieved. Simulation results verify that the microstrip patch quad is qualified to work as the multipolarized monopulse feed source by adjusting phases and amplitudes among the four feed ports. The metallic structure of this W-band multipolarized monopulse Cassegrain antenna is fabricated by using high-precision milling machine to assure the design parameters. At 94 GHz, the integral gain is 39.6 dBi and the aperture efficiency is 51.9%. Measurement results demonstrate the proposed antenna has excellent polarization synthesis and polarized monopulse performances further.

A compact multiband four port diversity-based antenna with high isolation between elements is proposed for multiple-input-multiple-output applications. The antenna resonates at following three bands: 1.95-2.5 GHz (covering UMTS, LTE 2300, and 2.4-GHz ISM bands), 3.15-3.85 GHz (covering WiMAX band), and 4.95-6.6 GHz (covering 5.2/5.8-GHz ISM bands). The stub-loaded meander-line antenna is loaded with split-ring resonators arranged in the form of a ring to enhance isolation by 17 dB at 2.4 GHz. All four elements radiate with equal efficiency with measured peak gains of 2.5, 3.7, and 4.4 dBi, respectively, in three bands and have a very low envelope correlation coefficient between elements. The overall size of the compact multiport antenna system is 0.26λ × 0.26λ × 0.01λ with a minimum isolation of 22 dB between its elements. The antenna elements and the isolation enhancement structure are fully planar for an easier integration.

A quad-band circularly polarized (CP) antenna for 2.4/5.3/5.8-GHz WLAN and 3.5-GHz WiMAX applications is proposed. Three CP modes operating at the 2.4/3.5/5.8-GHz frequency bands are first achieved by a patch antenna composed of an inverted-U-shaped radiator with additional I-shaped and L-shaped strips, all rotated by 45 $^\circ$ around the horizontal axis. By placing a simple frequency selective surface (FSS) of $6 \times 6$ square metallic patches under this antenna, 5.3-GHz linearly polarized (LP) signals are converted into CP signals, producing a quad-band CP antenna. The measured $-\hbox{10-dB}$ impedance bandwidth is 380 MHz (2.37–2.75 GHz) and 4.6 GHz (3.4–8 GHz). The measured 3-dB axial-ratio bandwidth reaches 5.4% (2.35–2.48 GHz), 8.3% (3.45–3.75 GHz), 3.7% (5.25–5.45 GHz), and 2.9% (5.7–5.87 GHz).

A four-port planar multiple input multiple output antenna system employing polarisation and pattern diversity technique is proposed. The antenna system, resonating at 2.4 GHz ISM band, includes a dual polarised two-port cross-patch antenna and an orthogonally polarised two-port square ring patch antenna. Undesired high coupling between elements is reduced by incorporating an interdigital structure on the ground. This reduces coupling between elements by 12.5 dB, ensuring a high isolation of about 28 dB between any set of elements in the antenna system. The overall size of the quad element antenna is about 0.5 × 0.5λ, which makes it fairly compact. The cross-patch antenna has low cross-polarisation levels, which reduces the coupling between its orthogonal elements. The narrow bandwidth of the higher order modes of the square ring antenna is doubled by adding half wavelength slits along its arms. All four elements have a 2:1 voltage standing wave ratio (VSWR) bandwidth of 85 MHz and have low envelope correlation in the operating band. The antenna is printed on a low cost FR4 substrate and does not require any intricate fabrication.

With quad-band-notched characteristic, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna is introduced in the paper. The UWB–MIMO system has two similar monopole elements and occupies 30 × 45 mm2. By inserting two L-shaped slots, CSRR and C-shaped stubs, four notched bands are achieved (3.25–3.9, 5.11–5.35, 5.5–6.06, and 7.18–7.88 GHz) to filter WiMAX, lower WLAN, upper WLAN, and X-band. Meanwhile, the isolation is obviously enhanced with three metal strips on the ground plane. Results indicate that the antenna covers UWB frequency band of 3.1 – 10.6 GHz except four rejected bands, isolation of better than −18 dB, envelope correlation coefficient of

This paper is in continuation of our previous published work, in which effect of user’s body is studied for quad band diversity antenna. The antenna has been successfully designed and studied in the free space. In this study, three kinds of user effects on previously proposed antenna are considered, namely, “Specific Anthropomorphic Mannequin (SAM) head and PDA hand (Talk mode)”, “Personal Digital Assistants (PDA) hand (Data mode)”, and “Dual hands (Read mode)”. There are two different positions of the quad band antenna over mobile circuit board is considered i.e., antenna at top position and bottom position of mobile circuit board. In the user proximity, the optimal location of antenna over circuit board is chosen for real application based on the antenna performance parameters i.e. S-parameters, diversity performances, and radiation performances. The specific absorption rate (SAR) for American standard (1.6 W/kg average over 1 g tissues) and European standard (2 W/kg average over 10 g tissues) is calculated for the top and bottom position of the MIMO antenna elements and it is found that the values of SAR is well below the standard limit of FCC as well as European standard. Based on the study, it is found that antenna at top position of mobile circuit board shows overall better performance in the presence of user’s body.

A compact planar quad element wideband antenna for multiple-input-multiple-output (MIMO) system is proposed in this communication. A single element consists of a partially grounded printed monopole antenna loaded with a split ring resonator. The bandwidth of the antenna is from 2.2 to 6.28 GHz (96.2%), which covers LTE (2.2–3.8 GHz), Bluetooth (2.4 GHz), WLAN (2.4 and 5.1–5.8 GHz), WiMAX (2.3–5.7 GHz), and ISM bands (2.4/5.2/5.8 GHz). The fabricated antenna has an isolation greater than 14 dB between its elements, with a peak gain of 4 dBi and a peak efficiency of 91%. Polarization diversity is employed to accommodate four elements in an FR4 substrate, with an overall dimension of $0.33\lambda \times 0.33\lambda \times 0.01\lambda $ . The antenna has a simple planar design which is easy to fabricate with no intricate process involved.

A novel dual-mode triple-band communication terminal antenna is proposed in terms of the quadrifilar helix antenna and the BeiDou satellite navigation system. First, the folded arms are introduced, and at the top of the quadrifilar helix antenna, the folded arms are connected to the helix arms by the series capacitors. Second, the above quadrifilar helix antenna is applied to coaxially collocate with an ultrahigh-frequency monopole antenna. Furthermore, to solve the electromagnetic compatibility issues, a sleeve is coaxially collocated around the monopole antenna within the quadrifilar helix antenna, and the sleeve structure dimension parameters are optimized. Third, the above quadrifilar helix antenna collocated with the ultrahigh-frequency sleeve monopole antenna is designed to the B1 and B3 bands, based on the BeiDou satellite navigation system, and the military reserved ultrahigh-frequency communication frequency band is also supported, which satisfies the performance requirements of the multi-function antenna system in the communication terminal of soldier combat system to support navigation service. Finally, some numerical and experiment examples are provided to illustrate the performance of the proposed communication terminal antenna. And it shows that the proposed antenna system can easily be integrated with the existing soldier combat system device which reduced the maintenance costs.

In this contribution a dual-band, dual-polarized microstrip antenna element for array applications is presented. The patch antenna is designed to operate simultaneously at around 30 and 20 GHz, the up- and downlink frequencies of modern Ka-band satellite communication systems. The antenna is smaller than half the freespace wavelength at 30 GHz to enable its utilization as array element of dual-band ground terminals. Integrating transmitter and receiver circuits allows, in turn, for a very compact active terminal solution. To minimize production cost, the design is carried out in standard multilayer printed circuit board technology. The antenna features two distinct polarization ports suitable for either dual linear or dual circular polarization if both ports are excited in quadrature. The single antenna design process is described in detail and simulation and measurement results are presented. Finally, different arrays based on this patch antenna are evaluated by simulation and measurements.

Compact modified T-slot circular patch antenna for multiple input multiple output (MIMO) applications, which has good response for four operating frequency bands is developed. Here the design consists of a circular patch with a new slot loaded T- shape on one side of the substrate and a feeder line on the other side of the substrate. A shorting pin is located between the patch and the feeder line. This proposed antenna resonates at the frequencies of 2, 4.8, 5.4, and 6.2 GHz covering the S-band, C-band, and LTE applications. The independent tuning of frequency bands is achieved by varying the length of the slots. By independent tuning of frequency bands, the selection of interested frequency band is achieved. The single element with miniaturized size of 1.945λ × 1.945 λ (30 × 30 mm2) is achieved including the feed line. The antenna has been tested for MIMO applications. The measured envelope correlation coefficient between the two elements, which are spaced 0.139 λ is

A quad-band planar compact diversity antenna for mobile handset devices is presented in this paper. The antenna unit of the proposed antenna is a “paperclip” structure consisted by an inverted L-shaped strip and a C-shape meander branch connected by a metallic via hole. The radiation structure of the proposed antenna is compact, 15.6×25mm 2 . Simulated and measured results show that the proposed antenna can operate at 0.915/2.45/3.5/5.8GHz WSNs, WLAN and LTE bands with quasi-monopole radiation patterns. Two diversity antenna geometry are compared and discussed in the overall size of 60mm × 100mm substrate similar like the size of modern mobile handset devices. A low Enveloped Correlation Coefficient(ECC) characteristic are achieved by the optimized diversity design. Together with compact volume, the proposed diversity antenna is a good candidate for mobile handset device applications.

A dual-feed small size full-metal-case FMC antenna for hepta-band LTE/WWAN operation in smartphone applications is presented. The antenna proposed here is an integrated part of the full metal case located at the top edge of the smartphone, and it only occupies a small volume of 5 mm × 70 mm × 6 mm. It has two feeding ports that are separately connected to an ON/OFF switch SW1 and SW2 for controlling the lower and higher operation bands, respectively. For the case when SW1 ON and SW2 OFF, Port-1 is engaged, and a lower operating band that covers the GSM850/900 operation 824-960 MHz is achieved. In contrast, Port-2 will be engaged for the case when SW1 OFF and SW2 ON, and with the aid of a wideband matching circuit, the antenna can induce a higher operating band that can cover the DCS/PCS/UMTS2100/LTE2300/LTE2500 operations 1690-2690 MHz. Detailed design considerations of the proposed FMC antenna are described, and both experimental and simulation results are also presented and discussed. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:595-601, 2016.

A novel method of enhancing cross-polarization discrimination (XPD) of a ${\pm }{45}^{\circ}$ dual-polarized base-station antenna, by addition of four parasitic elements placed in a square contour, is presented. First, it was established that high XPD at the broadside can be obtained by addition of four parasitic elements around a simple ${\pm }{45}^{\circ}$ dual-polarized base-station antenna. Second, we investigated the principle of wide beamwidth high XPD after studying magnitude currents on parasitic element, spacing between parasitic elements and length of parasitic elements. Finally, a ${\pm }{45}^{\circ}$ dual-polarized base-station antenna was designed, fabricated and measured. Measurement results are in good agreement with the results of simulation in terms of radiation pattern, gain, and Voltage Standing Wave Ratio (VSWR). In particular, the enhanced XPD is more than 20 dB at the boresight and more than 10 dB within ${\pm }{60}^{\circ}$ of the main lobe at the horizontal plane.

A compact quadruple band microstrip patch antenna with two rectangular notches is proposed and analysed for multiband applications. The proposed antenna structure is obtained from reference patch antenna by providing two rectangular notches on the radiating patch and their effects are investigated in terms of return loss, radiation pattern, current distribution and voltage standing wave ratio (VSWR). The proposed structure is simulated using electromagnetic solver Ansoft's high frequency structure simulator (HFSS) and results are in good agreement with measured results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1365–1369, 2016

This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program, No. 10040133) funded By the Ministry of Trade, Industry & Energy (MI, Korea).

A beacon antenna is proposed using in beacon device of digital flight data recorder for harsh environment. The antenna has a simple structure and works at the center frequency of 2.645 GHz. Its fabrication employs a low-cost and planar printed technique. The antenna contains a main patch and 3 derivative elements, act as radiators. The proposed antenna is designed by employing the genetic algorithm (GA). A prototype antenna is fabricated and measured. The measurement results agree with the simulation data and show that this antenna possesses encouraging features. For example, it has a well-formed radiation pattern with a high gain level of 6dBi, the antenna achieves an impedance bandwidth of 2.3% of the center frequency (2.613 GHz ∼2.675 GHz) for S11

A small-size reconfigurable loop antenna for mobile phone applications with a compact volume of $55 \times 5 \times 3$ mm3 is proposed. In addition to the traditional three loop antenna modes, namely, 0.5- $\lambda $ , 1- $\lambda $ , and 1.5- $\lambda $ modes, the proposed loop antenna also generates another 2- $\lambda $ mode. To cover more operating bands with such compact antenna volume, the reconfigurable technique is therefore applied by inserting an RF switch at the end of the proposed antenna to improve bandwidth at the low band. By combining the four working states of RF switch, the proposed antenna can cover GSM850/900, DCS1800, PCS1900, UMTS2100, and LTE2300/2500 bands with low specific absorption rate and high efficiencies.

This paper presents the design of triple band compact microstrip patch antenna with fractal elements. The antenna has been designed on FR4 substrate with thickness 1.6mm, dielectric constant 4.4 and resonant frequency of antenna is 3.2GHz. Gain of antenna is improved by addition of fractal elements to the nine corners of the nonagon patch. Introduction of fractal elements improved the gain from 1.24dB to 7.96dB and miniaturization takes place due to the decrease in resonant frequency from 3.38GHz to 2.88GHz on increasing the iteration number. The three iterations of antenna is designed and simulated by using HFSS V13 software and the designed antennas covers the frequency bands of WLAN, WiMax and other wireless applications which comes under the frequency ranges of S-band, C-band and X-band.

A multiband printed loop mobile phone antenna for LTE/WWAN/GNSS application is presented. It covers seven communication bands (VSWR < 3) and GNSS band (VSWR < 1.5). The so-called GNSS (global navigation satellite system) band includes COMPASS, GALILEO, GPS, and GLONASS. From the analysis of the structure, the coupled-fed antenna mainly consists of three parts: the feeding strip, shorted strip, and U-shaped parasitic coupling strip. The proposed antenna works in three resonant modes, respectively, at 860 MHz (0.25λ), 1620 MHz (0.5λ), and 2620 MHz (1λ). A solution is provided, by which the navigation antenna can be integrated into the communication main antenna to save space. The antenna not only can work in GSM850/900/1800/1900/UMTS2100/LTE2300/2500 bands but also covers the world’s four major navigation systems. Moreover, the proposed antenna can be easily printed on the circuit board without loading any lumped element and only occupies a small volume of 18 × 32 × 3 mm3, which is suitable for smartphone application. In addition, the redundant design of multinavigation system is quite favorable for the elimination of errors or shadow area caused by single navigation system, especially for outdoor investigation, national security, and so on.

For a video signal relaying application, a directive antenna element, which will be part of an array, is investigated. The element needs to achieve a bandwidth larger than 15% of the center frequency such that it can cope with environmental conditions like rain, fog, and icing. To be able to achieve such large bandwidth the thick wire concept is applied on a bi-quad antenna. The traditional wire bi-quad antenna is transformed into a planar thick wire variant where a 28% frequency bandwidth is achieved by broadening the copper tracks. Furthermore, the planar configuration is more rigid to be able to cope with mechanical stress during flight.

Novel axe-shaped circular microstrip quad band cost effective antenna with simple structure is developed. This design consists of circular patch with elliptical and circular slots loading provide an axe shape patch along with stubs offer quad bands. The proposed antenna provides resonance at the frequencies of 2.8, 4, 5.4, and 6.2 GHz which covers the applications of WLAN/WI-FI and WIMAX. The measured results of reflection coefficient and VSWR are presented. The proposed design provides minimum rejection ratio of 23 dB and maximum rejection ratio of 15 dB. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:400–402, 2016