Pair Of Antennas Research Articles

Dual-Band Antenna Pair With High Isolation Using Multiple Orthogonal Modes for 5G Smartphones

This communication presents a novel decoupling method to design a dual-band closely arranged multiple-input multiple-output (MIMO) antenna pair with high isolation for fifth-generation (5G) smartphones. By combining a bent loop and a T-shaped monopole into a compact space with a miniaturized size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.8\times $ </tex-math></inline-formula> 7 mm2, multiple orthogonal in-phase modes and out-of-phase modes are excited at two different bands, respectively, to decrease the mutual coupling. Although the bent loop is closely spaced to the T-shaped monopole, the proposed antenna pair exhibits high isolation of more than 24 dB in dual bands without any decoupling structures. An <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> 8 MIMO system operating at 3.3–3.6 GHz and 4.4–5.0 GHz is developed by arranging four such antenna pairs. The isolation is more than 12.8 dB, the envelope correlation coefficients (ECCs) are lower than 0.18, and the efficiencies are better than 71% and 68% in two bands for the proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> 8 MIMO system. The proposed MIMO system features dual-band operation, compact structure, and excellent isolation, which provides a promising solution for the 5G smartphone antenna design.

Bandwidth-Enhanced 5G Mobile Phone Antenna Pair With Tunable Electric Field Null

In this communication, a bandwidth-enhanced antenna pair with a tunable electric field ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field) null for the fifth-generation (5G) mobile phone application is presented. The proposed antenna pair is composed of a stub-loaded inverted-F antenna (IFA) and a simple feeding network. The stub-loaded IFA can obtain a wider impedance bandwidth and a feeding network is designed to excite the orthogonal dipole mode and adjust the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field null position. By adjusting the phase shifter in the feeding network, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -field null can be moved to the feeding position of the IFA, achieving excellent isolation performance. A sub-6 GHz antenna pair is simulated and shows an isolation of better 16.5 dB within the N78 (3.3–3.8 GHz) band. By arranging the proposed antenna pair along two long edges of the ground plane, an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> multiple-input multiple-output (MIMO) system is designed, fabricated, and measured. The measured results show that the MIMO system could achieve isolation of better than 19.5 dB and envelope correlation coefficients (ECCs) of lower than 0.03. The measured total efficiencies are greater than 43% for each port. The proposed antenna reveals a novel decoupling strategy for wider bandwidth while retaining the isolation performance and compact size based on a pair of orthogonal mode.

Wideband MIMO Antennas With Enhanced Isolation Using Coupled CPW Transmission Lines

This article presents a wideband printed-monopole antenna pair with enhanced isolation. A clear two-step method based on even-mode (EM) and odd-mode (OM) analyses is developed for antenna decoupling and matching: first, the OM input impedance of the antenna pair is matched by adjusting the element spacing; next, the EM input impedance is matched by adding a coupled TEM transmission line. Those two steps are independent and easy to implement. Notably, the use of a nondispersive coupled transmission line facilitates wideband decoupling and intrinsically allows an extremely small feed-point spacing. The proposed antenna pair is experimentally tested: it offers isolation higher than 20 dB and total efficiency higher than 87% from 3.7 to 7.3 GHz (a fractional bandwidth of 65.5%). The separation between the two feed points is only 5.6 mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.069~\lambda $ </tex-math></inline-formula> at 3.7 GHz). Furthermore, we construct a four-element multiple-input–multiple-output (MIMO) array by intersecting orthogonally two of the proposed antenna pairs at their central line, which offer an isolation level better than 20 dB from 3.8 to 7.4 GHz for every two ports. With a straightforward design process, compact feeding structures, and wideband performances, the proposed dual- and four-element MIMO antennas are promising for the fifth-generation wireless communication.

Radio-Frequency Near-Field Sensor Design for Minuscule Internal Motion

We present the improved design of a radio-frequency (RF) near-field sensor for minuscule internal motion inside structures and small animals. The design tradeoffs of the antenna placement and transceiver configuration are explored experimentally by a structural setup of the fluid stirrer. The sensor performance is benchmarked in various antenna configurations and quadrature baseband sampling settings. An optimized antenna pair holder design is then applied to a continuous touchless recording for the respiration and heartbeat of nestling and adult tree swallows noninvasively. Furthermore, we also built a low-power portable all-in-one RF sensor printed circuit board (PCB) using the system parameters from previous experiments. A 40-min experiment on a conscious and free-to-move 13-day-old nestling tree swallow for respiration monitoring was successfully conducted.

Closely-Spaced Half-Ring Patch Antenna Pair With Enhanced Isolation, Reduced Cross Polarization, and Consistent Beam

This letter proposes a copolarized and closely-spaced half-ring patch antenna pair (HRPAP) with loading of stubs and shorting pins for isolation enhancement and cross-polarization reduction. By inserting two stubs and adjusting gaps between the HRPAP, consistent resonant frequency, and equal quality factor of the odd and even modes can be simultaneously obtained, which contributes to high isolation of the HRPAP over a wide frequency range. Furthermore, four shorting pins are elaborately loaded so as to weaken the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -oriented current component of the HRPAP, by which the cross-polarization level in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane is significantly reduced. Finally, the proposed HRPAP is fabricated and measured. Both the simulated and experimental results show that the antenna has achieved an isolation level over 30 dB, cross-polarization reduction of about 8.8 dB, and consistent radiation patterns.

How Good Is a Tactical-Grade GNSS + INS (MEMS and FOG) in a 20-m Bathymetric Survey?

This paper examines how tactical-grade Inertial Navigation Systems (INS), aided by Global Navigation Satellite System (GNSS) modules, vary from a survey-grade system in the bathymetric mapping in depths less than 20 m. The motivation stems from the advancements in sensor developments, measurement processing algorithms, and the proliferation of autonomous and uncrewed surface vehicles often seeking to use tactical-grade systems for high-quality bathymetric products. While the performance of survey-grade GNSS + INS is well-known to the hydrographic and marine science community, the performance and limitations of the tactical-grade micro-electro-mechanical system (MEMS) and tactical-grade fiber-optic-gyro (FOG) INS aided with GNSS require some study to answer the following questions: (1) How close or far is the tactical-grade GNSS + INS performance from the survey-grade systems? (2) For what survey order (IHO S-44 6th ed.) can a user deploy them? (3) Can we use them for navigation chart production? We attempt to answer these questions by deploying two tactical-grade GNSS + INS units (MEMS and FOG) and a survey-grade GNSS + INS on a survey boat. All systems collected data while operating a multibeam system with the lever-arm offsets accurately determined using a total station. The tactical-grade GNSS + INSs shared one pair of antennas for heading, while the survey-grade system used an independent antenna pair. We analyze the GNSS + INS results in sequence, examine the patch-test results, and the sensor-specific SBET-integrated bathymetric surfaces as metrics for determining the tactical-grade GNSS + INSs' reliability. In addition, we evaluate the multibeam's sounding uncertainties at different beam angles. The bathymetric surfaces using the tactical-grade navigation solutions are within 15 cm of the surface generated with the survey-grade solutions.

Eight-port Diagonal Antenna with High Isolation and High Efficiency for 5G Smartphone

In this letter, an 8x8 multiple-input-multiple-output (MIMO) antenna that operates in the sub-6 GHz (4.7-5.1 GHz) spectrum for 5G MIMO smartphone applications is presented. The design consists of a fully grounded plane with closely orthogonal antenna pairs placed symmetrically on the corners of the smartphone and each antenna element consists of an F-type monopole with dimensions of 18x7.5mm2. Firstly, the diversity characteristics of orthogonally placed antennas are used to reduce the coupling between antennas. On the other hand, diagonal antennas are connected by a neutral line (NL) to further improve isolation and etched slots on the ground to reduce the coupling between antenna pairs. A good frequency bandwidth (S11 &lt; -10 dB) of 4.7-5.1 GHz has been obtained for the MIMO antenna, and the isolation is lower than 16 dB. In addition, total efficiency (TE) is greater than 77.5%, and the envelope correlation coefficient (ECC) is lower than 0.025. The fabricated antenna prototype is tested and offers good performance.

Wideband MIMO Antennas for 5G Mobile Terminals

An approach of using the concept of CM (common mode) and DM (differential mode) to design two wideband antennas in a pair has been proposed. The two antennas in the antenna pair have wide bandwidth and high isolation, though they share the same radiator and total electric length of the antenna pair is just a half wavelength. A rigorous analysis has been presented to explain and illustrate the operating principle of the wideband antenna pair. An antenna design example operating in 5G New Radio (NR) N1, N2, N3, N7, N38 and N41 bands with frequency ranging from 1.71-2.69 GHz has been examined to demonstrate the effectiveness of the proposed approach. The simulated results, including S-parameters, antenna total efficiency and ECC (envelope correlation coefficient), are in good agreement with measured ones.

Dielectric Constant-Based Grain Mass Estimation Using Radio Frequencies Sensing Technology

HighlightsRadio frequency sensing technology was used to estimate clean grain mass based on grain moisture content and grain properties.Multiple variable regression analysis was used to develop grain mass estimation model.A grain mass estimation model with high R2 was developed by introducing dielectric properties and phase angle.Parameter of dielectric constant e' indicated the domination of moisture content in grain mass estimation model.Abstract. Grain mass estimation is critical in many precision agriculture applications, especially in yield monitoring during harvest procedures. A new clean grain mass estimation method using Radio Frequency (RF) sensing technology is discussed in this paper. RF sensing technology is sensitive to moisture content and grain properties. In this study, a vector network analyzer (VNA) and a pair of horn antennas were used to collect phase shift and attenuation data from 1 to 18 GHz of grain samples (soybean, canola, and corn) on a static testbed in an anechoic chamber. Using multiple variable linear regression analysis, a comprehensive clean grain mass estimation model was developed based on the dielectric properties of the grain samples derived from the S-Parameters at 13 GHz. Dielectric (e') constant/properties and phase shift were introduced into the regression models and generated a grain mass estimation result with R2 values of 0.976, 0.977, and 0.989 for soybean, canola, and corn samples, respectively. The results indicate that RF sensing technology can reveal how grain attributes interact with electromagnetic fields at a certain frequency and has the potential to provide more accurate sensing methods for estimating grain mass in multiple precision agricultural applications. Keywords: Keywords., Dielectric properties, Grain mass estimation, Microwave frequency, Phase shifts, Radio frequency sensing.

Method of Characteristic Modes Analysis and Manipulation for Antenna Design by Using Generalized Partial Element Equivalent Circuit

A method of analyzing characteristic modes (CMs) of antennas with multiple lumped <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> loads is proposed based on the full-wave generalized partial element equivalent circuit (GPEEC) model. Different with traditional CMs analysis methods, this method can be integrated into an optimization algorithm. With this powerful engine, we can develop a systematic method to manipulate radiation CMs of a mobile terminal while preserving its aesthetic structure features of the industrial design. This method can reveal all possible radiation structure performances as traditional methods and even create new possible radiation modes to improve antenna performance. With the GPEEC model, a comprehensive analysis of antennas can be achieved simultaneously, including but not limited to simulating time-/frequency-domain responses, evaluating radiation efficiency contributed by the self- and mutual radiated power separately, and plotting current and field distribution. Three design examples are demonstrated, including analyzing the working mechanism of the self-curing decoupling technique for mobile terminals from the view of CMs, extending the bandwidth of an antenna in LTE-A low-frequency bands, and creating a pair of MIMO antennas in the low LTE-A bands. These examples are verified theoretically and experimentally, showing the high potential of this method in analyzing and designing antennas for mobile terminals.

A Design for a Wide-Band Antenna Pair Applied for Mobile Terminals at the Sub-6 GHz Band

To meet the requirements of a high transmission rate and strong communication quality for mobile terminals, a planar antenna printed on a 0.8-mm-thick FR-4 substrate is proposed in this paper. The structures are compact, with a size of 23×6 mm2. The performance of a single antenna pair in a 75×35 mm2 ground plane shows the advantages of both ultra-wide bandwidth and high isolation. The operating frequency of −6 dB is 54% (3.3 GHz–5.9 GHz). To solve the mutual coupling effects exiting in the antenna pair, a hybrid strip defected grounding structure (DGS) is added in the middle of neighboring antenna elements, and good isolation performance of lower than −13 dB is achieved. The evolution and analysis of the proposed antenna pair are given to investigate the operating principle. To verify its practicality, an eight-port antenna system in 150×70 mm2 ground plane is constructed along two frames of the smartphone board. The MIMO antenna system performance is simulated and texted. The results show a bandwidth of 3.4–5.2 GHz (−6 dB), an isolation performance lower than −10 dB, an ECC lower than 0.01, and a total efficiency of 46–84%. In addition, the performance of the antenna system under single handheld conditions is also discussed. The correlation results show that the designed antenna pair has good data transmission and interference resistance capability, which proves that this is an excellent antenna model for application in mobile terminals.

The collimation of the Bessel Gauss beams using a composite optical system consisting of multiple pairs of Cassegrain antennas

Collimation of Bessel Gauss beams has always been a problem and has hindered its application in free space optical communication. In this work, the Bessel Gauss beam can have a diffraction-free distance of 10,000 km with the aid of a new composite optical system. The optical system consists of several pairs of Cassegrain antennas, each pair of which allows the divergence angle of the beam to be compressed to one-tenth of its original size. Bessel Gauss beams with a topological charge of one to five can achieve an efficiency of 81.05%, 88.68%, 88.68%, 85.75%, 80.12% when the wavelength of beams is 860 nm, after 10,000 km propagation in the composite optical system. At this time, the corresponding divergence angles of the first to fifth order beams are 0.118 μrad, 0.141 μrad, 0.169 μrad, 0.184 μrad, 0.192 μrad, respectively. We give a relationship between the ability to compress the angle of divergence of the system and the number of primary and secondary mirror pairs contained in the antenna and the focal length ratio of primary and secondary mirrors, which is verified by calculations that guide the design of the new system. It is possible to design an antenna suitable for different application scenarios by changing the number of primary and secondary mirror pairs and the focal length ratio of the primary and secondary mirrors.

Localizing RFIDs in Pixel Dimensions

Radio Frequency IDentification (RFID) is emerging as a vital technology of the Internet of Things (IoT). Billions of RFID tags have been deployed to locate daily objects such as equipment, pharmaceuticals, vehicles, and so on. Unlike previous solutions that focus on localizing tagged objects in the world coordinate system in reference to reader antennas, this work exploits a system, called RFCamera, that can identify and locate RFID-tagged objects in images with pixel dimensions. Our core insight is that an image is a visual AoA profile in terms of lights, which is resulted from the pinhole camera model. Similarly, we generate an RF image derived from the AoA profile of a tag using the same pinhole model as the camera. Consequently, the locations of visual entities corresponding to tagged objects are highlighted by comparing two types of images. To this end, we customized a camera system equipped with a pair of rotatable reader antennas. Our experimental evaluation demonstrates that RFCamera enables a mean error of 5.7∘ and 2.9∘ at azimuth and elevation angle estimation, respectively. It can locate a visual entity with a mean error of 51 pixels (i.e., ≈1.3 cm at 96 dpi) in a 640× 480 image.

Compact Tightly-Coupled Self-Decoupled MIMO Antenna Using Internal Hybrid Tunning

This brief offers a compact, tightly-coupled, self-decoupled vias-based multiple-input multiple-output (MIMO) antenna pair with a common ground for a 5G system. The projected design comprises modified T-shaped tightly-coupled antenna elements. It is effortlessly helping to achieve sound decoupling across the desired band without using any extra decoupling circuit between the elements. It is revealed that the structure of the self-decoupled MIMO antenna tunes the inductive and capacitive (hybrid) effect of elements, which helps to achieve the decoupling of antenna elements. A relevant equivalent circuit model for coupled and decoupled MIMO antenna is proposed to validate the insight operation of this proposed theory. The hybrid tuning among the MIMO antenna elements reduces the coupling effect mutually by modifying the antenna shapes. The proposed self-decoupled MIMO antenna pair demonstrates low mutual coupling across the 5G NR frequency bands: n48 and long-term evolution (LTE) band 42/52 (3.2–3.6 GHz) with good diversity characteristics. Moreover, the one proposed design structure can offer dual-band self-decoupling features. The proposed structure provides 3.2-3.6GHz and 3.95-4.115GHz frequency bands. This structure can be optimize further to achieve dual-band/ wideband resonance in the design.

The “Co-centered Orthogonal Loop/Dipole” (COLD) Array’s “Spatial Matched Filter” Beam-Steering

Consider an electrical dipole and a magnetic loop—co-centered and axially aligned. This compact pair of line antennas is centro-symmetric and polarization-sensitive but suffers no mutual coupling. Their “spatial matched filter” beam-steering bias will be analytically derived here for the first time in the open literature. The key findings include the following: 1) The elevation-azimuthal directional beam-pattern is multiplicatively separable from the polarizational beam-pattern. 2) No pointing bias exists in polarization (i.e., the nominal “look polarization” always gives the actual peak polarization). 3) No polarizational sidelobe exists. 4) The actual peak polar direction is always normal to the “co-centered orthogonal loop and dipole” array axis regardless of the nominal polar “look direction.”

A High-Efficiency Microstrip Antenna Pair with Similar Pi-Shaped Decoupling Structure for 3.5 GHz 5G Ultrathin Smartphones

In this paper, a low profile and high-efficiency decoupling antenna pair for multiunit smartphones is proposed using a similar π-shaped feed structure that can excite the dipole radiation mode of microstrip antenna. Ordinarily, symmetrical single-port T-shaped microstrip antennas can only excite monopole modes of bilateral radiation. This paper changes the vertical feeding microstrip structure into two oblique, similar π-shaped feeding structures. This oblique feeding structure can excite the dipole mode of unilateral radiation of the microstrip antenna. Using this method, the antenna design can be simplified, and the low-coupling independent radiation on both sides of the microstrip antenna can be freely controlled without the need for additional structures. Considering the ultra-thin characteristics of 5G smartphone devices, the parameters of the antenna are further optimized: the optimized antenna profile is only 3.7 mm. The measured results show that the 2 × 2 microstrip antenna pairs can effectively cover the 3.5 GHz band (3.4–3.6 GHz), with a coupling that varies from −16.14 dB to −11.01 dB and an efficiency that varies from 80% to 94.1%. The 8 × 8 MIMO smartphone antenna results show that the coupling varies from −20.1 dB to −12.17 dB, the efficiency varies from 79.72% to 93.7%, and the envelope correlation coefficient (ECC) is lower than 0.05. The microstrip antenna decoupling pair with a similar π-shaped feed structure proposed in this paper has high efficiency and low-profile characteristics have important application value in the decoupling design of 3.5 GHz 5G ultra-thin smartphone antennas.

Dual-Band Highly Isolated Eight-Element MIMO Antenna for 5G Mobile Phone

Based on the characteristic mode analysis (CMA) theory, a compact dual-band dual antenna pair with high element isolation function for 5G mobile terminal is proposed and designed in this paper. The antenna pair is composed of a pair of symmetrical stacked F-shaped radiators printed on the outside of the side frame, perpendicular to the main board. Based on the proposed decoupled antenna pairs, four pairs of antenna pairs are placed at both ends of two long side plates, and an 8-element MIMO antenna is proposed. High isolation in the operating frequency bands are achieved by using grounding branches and defective ground structure (DGS). All radiation elements are etched on a low-cost FR4 substrate with a total size of 150 × 75 × 6.8 mm3. The prototype of the antenna array is fabricated and measured. The working range of the antenna pair can cover 3.4GHz-3.6GHz,4.8GHz-5GHz 5G frequency bands and 5GHz-6GHz WLAN / WiFi / WiMax frequency bands. Besides, the isolation between any adjacent array elements are also &gt; 15dB and &gt; 16dB respectively, the total efficiency are 52%–75% and 58%–88% respectively, and the measured envelope correlation coefficients (ECC) are &lt;0.16. Furthermore, user’s head effects are investigated and desirable results are obtained. The above results show that this proposed antenna array is a good candidate for MIMO applications in 5G smartphones.

Compact frequency reconfigurable MIMO antenna pair with high isolation for 5G mobile applications

Compact frequency reconfigurable <scp>MIMO</scp> antenna pair with high isolation for <scp>5G</scp> mobile applications

Design of Wideband Decoupling Antenna Pairs for 5G Portable Devices at N77/N78/N79 Bands.

We proposed an antenna pair that is applicable for mobile terminals: a type of coupling feed planar antenna that has a size of 28×6&amp;nbsp;mm2, a wide band, coupling suppression and compact size. Different from the conventional antenna design, the process of band expansion comes from a dual-band antenna pair and is based on characteristic modes theory (CMA). By observing characteristic current distributions, the optimization emphasis is placed on current sensitive parts in antenna structures, which is an effective method to create or modify resonant points for exciting band potential. Meanwhile, the multiple defective ground structure (DGS) is introduced for isolation enhancement. The -10 dB bandwidth of 3.23-5.24 GHz can be realized, and the isolation of two antenna pairs with only 2 mm spacing is lower (-17.34 dB). The eight-port MIMO system constructed by four proposed antenna pairs has been fabricated. The simulated and measured results of MIMO indicate that its -10 dB operating bandwidth can work at N77/N78/N79/WLAN 5 GHz bands. Moreover, a lower ECC of less than 0.04 and a high efficiency of more than 60% can be obtained, which confirms that it is capable of excellent data transmission as a terminal MIMO antenna system.

Millimeter-Wave Imaging Using a Rotating Dynamic Antenna Array and Noise Illumination

We present a novel approach to millimeter-wave imaging that combines a new dynamic antenna array concept with active illumination by means of noise signals and interferometric image formation. The concept is based on a sparse linear array of receiving antennas that is dynamically rotated about its centroid, combined with three noise transmitters that illuminate the scene. Cross-correlations of the scattered signals received by individual array elements provide spatial frequency samples of the scene, from which the scene can be reconstructed via inverse Fourier transform. As the spatial frequency sampled by an antenna pair is dependent on the antenna baseline vector, dynamic rotation of the linear array generates sampling curves in the spatial frequency domain, providing a denser sampling function and a more accurate scene reconstruction. While traditional static interferometric imaging arrays utilize nearly an order of magnitude fewer antenna elements than phased arrays, our dynamic array concept relies only on a sparse linear array, further reducing the number of hardware elements required. We discuss the design of a 38 GHz dynamic antenna array imaging system and present measurements of multiple reflecting objects.