Array Prototype Research Articles

Wideband Endfire Antenna Array for Future Short-Range Communications

A broadband, unidirectional, phased array is proposed. Single antenna element of the prototyped array is a broadband windmill-like shaped antenna. Four elements of this antenna are fed by a power divider and are configured in a novel semicircular-shaped, angular-phased array. A phase difference of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $</tex-math> </inline-formula> /4 was introduced by optimizing the angular path difference among four antenna elements in the array. Total 21.5% of size reduction is achieved by introducing angular-phased array in comparison with the conventional linear-phased array. The array of radius 65 mm is prototyped on the Rogers RO4232 substrate for the operating frequency range 9.35–42.89 GHz. The proposed array configuration can maintain an average gain of 8.54 dB and average radiation efficiency of 69.71% in the entire operating frequency range while exhibiting a peak gain of 11.86 dB. The presented array exhibits highly directional behavior in the endfire direction, with the 3-dB angular beamwidth in the range from 15.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\circ$</tex-math> </inline-formula> to 76.7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\circ$</tex-math> </inline-formula> . To the best of the authors’ knowledge, any comparable state-of-art has not been reported yet in the literature that could provide such a large impedance bandwidth in sub-mmWave range. The proposed array may find its applications for future indoor and outdoor short-range communication networks.

Nonuniform Amplitude Transmitarray for Multibeam Including Near-Field Focusing

This article presents a nonuniform amplitude transmitarray for a multibeam that includes near-field focusing, based on a frequency selective surface (FSS). Each cell on the FSS is fed by a slot array and its feeding magnitude is adjusted by the slot position. The phase sets required for near-field focusing and far-field steering are controlled by the cell size of the FSS located above each slot. To confirm the performances of the antenna, a multibeam antenna for beam focusing and steering is designed. The required phase and amplitude of each cell are simply calculated and optimized by the principle of superposition. Finally, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6 \times 4$ </tex-math></inline-formula> array prototype antenna operating at 5.8 GHz is realized, and its characteristics are measured. The antenna can simultaneously focus on a near-field spot and radiate in the desired far-field direction. The measured and simulated results are found to be in good agreement.

Design and Characterization of the Fully Metallic Gap Waveguide-Based Frequency Selective Radome for Millimeter Wave Fixed Beam Array Antenna

This article presents a bandpass frequency selective surface (FSS) radome based on fully metallic gap waveguide (GW) technology. The element of the proposed FSS radome consists of a conventional cross-dipole slot etched on metallic plates and positioned over a groove GW cavity. A design with a single GW-cavity layer was initially produced which was later optimized for performance, to comprise a dual GW-cavity layer, while considering both functionality and manufacturability. It is shown that the proposed FSS element offers a stable and wide bandpass (from 26 to 30 GHz) performance in the broadside direction for both transverse electric (TE) and transverse magnetic (TM) polarizations. For oblique angle of incidence, the suggested FSS element works up to 30° with a reduction in usable bandpass bandwidth performance to 26–28 GHz for both TE and TM polarizations. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20 \times 20$ </tex-math></inline-formula> -element GW-FSS array prototype has been fabricated and measured, which was integrated with a fixed-beam array antenna to further validate its functionality as a filtering radome. The findings show an excellent agreement between simulations and measurements. Hence, the proposed GW-FSS represents a great opportunity to develop an all-metallic FSS with low insertion loss, sharp-roll-off filtering, wideband performance, and inexpensive fabrication cost.

A Low-Profile Ultra-Wideband and Wide-Scanning Phased Array for UHF Applications

This article presents a novel low-profile ultra-wideband and wide-scanning array antenna using the transversely connected folded tightly coupled dipoles array (TCF-TCDA). The tightly coupled folded dipole arms are used to extend the operational frequency band with a simple feed structure. The capacitively-loaded metallic walls are adopted to move the problematic common-mode resonance out of the desired band and mitigate the bandwidth-limiting loop mode at the lower frequency, as well as reducing the weight and cost. A meta-surface-based wide angle impedance matching (MS-WAIM) layer is used to improve the beam scanning ability and lower the antenna profile, which consists of the star-shaped patches loaded on the dipole element. To demonstrate the wideband and wide scanning-range capability, a prototype is designed with an 8:1 bandwidth (0.41–3.3 GHz) at broadside, a scanning range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm \mathrm{75}^{\circ }$ </tex-math></inline-formula> from 0.5 to 3.25 GHz (6.5:1 bandwidth) in the E- and D-planes and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm \mathrm{50}^{\circ }$ </tex-math></inline-formula> from 0.6 to 3.3 GHz (5.5:1 bandwidth) in the H-plane for active VSWR < 3.6. The proposed antenna has a very low profile, which is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.07\lambda _{\mathrm {low}}$ </tex-math></inline-formula> at the lowest operating frequency. A 16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 16 array prototype is fabricated and measured. Experimental results show that the design and measurement results have good agreement. The proposed antenna has an ultra-wide bandwidth, a wide scanning range, a very compact size and a low cost, which is a good candidate for modern wireless system.

A Broadband Circularly Polarized Planar Antenna Array Using Magneto-Electric Dipole Element With Bent Strips for Ka-Band Applications

This letter proposes a Ka-band broadband circularly polarized (CP) planar array based on the magneto-electric (ME) dipole structure. The antenna element consists of linearly polarized (LP) ME-dipole and two rotationally symmetrical bent strips. The two strips are connected to the opposite side of the LP ME-dipole to obtain a rotating electric field required by CP radiation. A feed structure of microstrip is implemented to excite the antenna element through an H-shaped coupling slot. The tightly coupled array technique is adopted to enhance the axial ratios (ARs) of the element. The proposed CP element realizes an AR bandwidth of 28%. Then, an 8 × 8 array with a 1-to-64 full-corporate feeding network is designed for experimental validation. The test results indicate that the 8 × 8 array prototype exhibits an impedance bandwidth of 50% covering 24 to 40 GHz, a 3 dB AR bandwidth of 28% covering 26.7–35.3 GHz, a gain between 20.6 and 22.1 dBic over the whole overlapped bandwidth, and a radiation efficiency higher than 75%. Attributed to the excellent CP performance and ease of integration with front-end circuits, the designed array is a good select for Ka-band wireless and satellite communications.

Theory of continuously curved and phased line sources for sound reinforcement

To supply large audience areas uniformly with amplified direct sound, large-scale sound reinforcement often employs line-source loudspeaker arrays adapted to the listening area by either adjusting the angles or delays between their individual elements. This paper proposes a model for such or smaller line-source loudspeakers based on a delayed Green’s function integrated over an unknown contour. For a broad frequency range, stationary phase approximation yields a differential equation that we utilize to find a curve and delay progression providing direct sound levels rolling off with −6β dB per doubling of the distance; curve and phase designs can also be mixed to meet simultaneous targets using multiple design parameters β. The effectiveness of the formalism is proven by simulations of coverage, directivity, and discretization artifacts. Measurements on a miniature line array prototype that targets medium-scale immersive sound reinforcement applications verify the proposed theory for curvature, delay, and mixed designs.

Ka-Band Huygens Antenna Array With Very High Aperture Efficiency and Low Sidelobes

A Ka-band Huygens antenna array with extremely high aperture efficiency (AE) and low sidelobe levels is reported for 5G millimeter-wave (mm-wave) wireless applications. The basic array element is an innovative Huygens subarray consisting of two open rectangular waveguides that form an aperture consisting of a 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 set of orthogonal, tightly coupled electric and magnetic elements separated by a virtual gap that are balanced, in- phase, and radiate Huygens cardioid patterns. A larger 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times16$ </tex-math></inline-formula> element array is then realized with 64 of these 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 subarrays. With excitations of equal amplitude, the full broadside-radiating array achieves an AE up to 97.5% in the operating bandwidth, which is very close to the 100% limit associated with an ideal uniform aperture distribution. Moreover, a highly efficient and compact feed network with tapered-amplitude and in- phase excitations from the array center to its edges is designed to achieve sidelobe and backlobe levels less than −20 dB. The −10 dB impedance bandwidth covers 26.7–29.65 GHz, and the peak realized AE (RAE) reaches 82%. A full-aluminum array prototype was fabricated with standard machining processes and tested. The measured performance characteristics agree well with their simulated values, confirming the efficacy of their designs.

DMPRA: A Dynamic Reconfiguration Mechanism for a Dual-Mode Programmable Reconfigurable Array Architecture

To improve the performance and power efficiency of various algorithms in specific applications, reconfigurable architecture has become an effective choice in academia and industry. However, due to the slow context updates and the insufficient flexibility, the existing reconfigurable architectures suffer from performance bottlenecks. Therefore, this paper proposed a dynamic reconfiguration mechanism applied to dual-mode programmable reconfigurable array architecture. This mechanism adopts Huffman-like coding and mask addressing, and through the H-tree transmission network, it can transmit the reconfiguration instruction/context to a specific processing element or processing element cluster in unicast, multicast, or broadcast modes within a clock cycle and shut down unnecessary processing elements or processing element clusters according to the current configuration. Meanwhile, a homogeneous reconfigurable array is designed to verify the correctness and effectiveness of the proposed dynamic reconfiguration mechanism. In this array, the processing element supports both instruction flow and data flow modes. Finally, the proposed work is implemented in register transfer level synthesis and a field-programmable gate array prototype, and its performance is verified using high-efficiency video coding algorithm. The results show that the proposed reconfiguration mechanism can effectively improve the hardware resource utilization and reconfiguration efficiency, it also can achieve the performance breakthrough of the reconfigurable architecture.

An Uninterrupted Processing Technique-Based High-Throughput and Energy-Efficient Hardware Accelerator for Convolutional Neural Networks

This article proposes an uninterrupted processing technique for the convolutional neural network (CNN) accelerator. It primarily allows the CNN accelerator to simultaneously perform both processing element (PE) operation and data fetching that reduces its latency and enhances the achievable throughput. Corresponding to the suggested technique, this work also presents a low latency VLSI-architecture of the CNN accelerator using the new random access line-buffer (RALB)-based design of PE array. Subsequently, the proposed CNN-accelerator architecture has been further optimized by reusing the local data in PE array, incurring better energy conservation. Our CNN accelerator has been hardware implemented on Zynq-UltraScale + MPSoC-ZCU102 FPGA board, and it operates at a maximum clock frequency of 340 MHz, consuming 4.11 W of total power. In addition, the suggested CNN accelerator with 864 PEs delivers a peak throughput of 587.52 GOPs and an adequate energy efficiency of 142.95 GOPs/W. Comparison of aforementioned implementation results with the literature has shown that our CNN accelerator delivers 33.42% higher throughput and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.24\times $ </tex-math></inline-formula> better energy efficiency than the state-of-the-art work. Eventually, the field-programmable gate array (FPGA) prototype of the proposed CNN accelerator has been functionally validated using the real-world test setup for the detection of object from input image, using the GoogLeNet neural network.

A Two-Stage Method for Routing in Field-Programmable Gate Arrays with Time-Division Multiplexing

Emerging applications widely use field-programmable gate array (FPGA) prototypes as a tool to verify modern very-large-scale integration (VLSI) circuits, imposing many problems, including routing failure caused by the limited number of connections among blocks of FPGAs therein. Such a shortage of connections can be alleviated through time-division multiplexing (TDM), by which multiple signals sharing an identical routing channel can be transmitted. In this context, the routing quality dominantly decides the performance of such systems, proposing the requirement of minimizing the signal delay between FPGA pairs. This paper proposes algorithms for the routing problem in a multi-FPGA system with TDM support, aiming to minimize the maximum TDM ratio. The algorithm consists of two major stages: (1) A method is proposed to set the weight of an edge according to how many times it is shared by the routing requirements and consequently to compute a set of approximate minimum Steiner trees. (2) A ratio assignment method based on the edge-demand framework is devised for assigning ratios to the edges respecting the TDM ratio constraints. Experiments were conducted against the public benchmarks to evaluate our proposed approach as compared with all published works, and the results manifest that our method achieves a better TDM ratio in comparison.

Highly Compact Integrated Sub-6 GHz and Millimeter-Wave Band Antenna Array for 5G Smartphone Communications

In this article, a dual-band integrated compact phased-antenna array is proposed for fifth-generation (5G) smartphone communication. The proposed single-layered substrate-based antenna array has a dual band, wideband, high gain, and wide beam-steering function. The dual bands were achieved by passive integration of meandered lines and a microstrip patch antenna using a dual-stub-based filter. Owing to the small size of the antenna array (56.65 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times4.95$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times0.508$ </tex-math></inline-formula> mm), it was installed on both the top and side metal frames of a smartphone in a vertical position, allowing a wide beam coverage with a high gain. The proposed antenna provided the −6 dB bandwidths of 250 and 3520 MHz at 3.5 and 28 GHz, and the −10 dB bandwidths of 110 and 1890 MHz were observed at 3.5 and 28 GHz, respectively. The radiation performance with a smartphone model and a hand phantom were analyzed in detail. Furthermore, a safety study on the power density (PD) and specific absorption rate (SAR) of the arrays with frequency-dependent hand and head models was conducted. Finally, we fabricated an antenna array prototype, and compared the measured results with the simulation results, which showed a good agreement.

Chemiresistive Sensor Arrays for Gas/Volatile Organic Compounds Monitoring: A Review

Gas detection and monitoring are essential due to their direct impact on human health, environment, and ecosystem. Chemiresistive sensors are one of the most used classes of sensors for monitoring and measurement of gases thanks to their ease of fabrication, customizability, mechanical flexibility, and fast response time. While chemiresistive sensors can offer good sensitivity and selectivity to a particular gas in a controlled environment with known interferences, they may not be able to differentiate between various gases having similar physiochemical properties under uncontrolled conditions. To address this shortcoming of chemiresistive gas sensors, sensor arrays have been the subject of recent studies. Gas sensor arrays are a group of individual gas sensors that are arranged to simultaneously detect and differentiate multiple cross‐reactive gases. In this regard, various sensor array technologies have been developed to differentiate a given set of gases using multivariate algorithms. This review provides an insight into the different algorithms that are used to extract the data from the sensor arrays, highlighting the fabrication techniques used for developing the sensor array prototypes, and different applications in which these arrays are used.

Intra-Lid Multi-Core Vapor Chamber Architecture for Heterogeneous Electronic Packages: Technology Concept to Prototype Evaluation

Thermal management of future heterogeneous electronic packages with extreme heat fluxes relies on effective spreading of heat in the package lid. Intra-lid integration of vapor chambers is a promising strategy for simultaneous dissipation of large total heat loads and localized high-flux hot spots. However, conventional vapor chambers comprising a single vapor core require relatively thick evaporator wicks to prevent dry out at high total heat loads, thereby imposing a large temperature drop across the wick at the hot spot location. We recently proposed a cascaded multi-core vapor chamber (CMVC) architecture comprising a single-core vapor chamber stacked on an array of smaller footprint vapor cores having relatively thinner wicks. The multi-core array is designed to spread heat from arbitrarily distributed high-flux hot spots before they enter the top vapor chamber having a thicker wick. Then, the top vapor chamber spreads the high total heat loads to the base of the mounted heat sink. To evaluate the proposed CMVC technology, we make a weighted decision to identify an appropriate minimum viable prototype for subsequent design and testing. A reduced-order model is used to determine the dimensions and properties of the wick and vapor core that minimize the temperature drop across the down-selected multi-core vapor chamber architecture for a given power map, considering manufacturing process constraints. Finite element analysis (FEA) simulations are employed to decide a condenser wall thickness that avoids permanent deformation in the vapor chamber architecture under a mechanical load. A prototype is manufactured by a commercial vendor following these parameters and manufacturing constraints. As predicted by the thermal model, experimental characterization of this first-reported multi-core vapor chamber array prototype offers a notable reduction in temperature drop relative to a benchmark solid copper spreader, owing to attenuation of hot spots at a low temperature difference.

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.

A Multipolarized Planar Phased Array for LEO SATCOM Applications

This letter presents a scalable multipolarized planar phased array for the low earth orbit satellite communication application. A dual-polarized aperture-coupled patch element antenna is proposed for designing the array, which can provide dual-linear polarization (LP) and dual-circular polarization (CP). The rotated feed technique is adopted to reduce the cross-polarization level. By using 8-channel beamformer chips and the multilayer printed circuit board technology, a phased array prototype with good electromagnetic shielding performance, high integration, and low cost is designed, fabricated, and measured. For dual-LP radiation, it steers up to the scan angles (±50°) with a scan loss less than 3.5 dB, and a cross-polarization level lower than −30 dB in azimuth/elevation plane and −15 dB in diagonal plane. For dual-CP radiation, it steers up to the scan angle (±50°) with a scan loss less than 3 dB and an axial ratio less than 3 dB. The phased array developed in this letter can be scaled to larger arrays and provides feasibility for the production of low-cost phased arrays.

Synthesizing Shaped-Beam Cylindrical Conformal Array Considering Mutual Coupling Using Refined Rotation/Phase Optimization

A novel method of synthesizing shaped-beam cylindrical conformal array by rotating the antenna elements and optimizing their excitation phases is presented. Rotation of antennas on curved surface is mathematically described by rotating its vectorial active element pattern (VAEP) in its local coordinate system (LCS). Then the scalar patterns and polarization unit vectors of all the rotated VAEPs are properly transformed and then interpolated at a unified angle sampling grid in a common coordinate system, where they are summed to obtain an approximated array expression. With this expression, element rotations and phases can be optimized using the constriction factor particle swarm optimization (CF-PSO) to synthesize desired shaped-beam pattern with controlled sidelobe level (SLL) and cross-polarization level (XPL). However, since rotations on curved surface introduce considerable variations to the element curvature and mutual coupling (MC), the synthesized array pattern would have considerable errors. A refined strategy is adopted then to improve the synthesis accuracy. The proposed method uses uniform amplitude weighting, thus saving many unequal power dividers. Three typical shaped pattern synthesis examples are provided to show the effectiveness of the proposed method. A cylindrical array prototype with 24 rotated U-slot loaded patch antennas is fabricated and measured for practical validation.

Scalable, Dual-Band Metasurface Array for Electromagnetic Energy Harvesting and Wireless Power Transfer.

A dual-band metasurface array is presented in this paper for electromagnetic (EM) energy harvesting in the Wi-Fi band and Ku band. The array consists of metasurface unit cells, rectifiers, and load resistors. The metasurface units within each column are interconnected to establish two channels of energy delivery, enabling the transmission and aggregation of incident power. At the terminals of two channels, a single series diode rectifier and a voltage doubler rectifier are integrated into them to rectify the energy in the Wi-Fi band and the Ku band, respectively. A 7 × 7 prototype of the metasurface array is fabricated and tested. The measured results in the anechoic chamber show that the RF-to-dc efficiencies of the prototype at 2.4 GHz and 12.6 GHz reach 64% and 55% accordingly, when the available incident power at the surface is 3 dBm and 14 dBm, respectively.

Ultra‐wideband planar patch antenna array using multimode resonant antenna element for millimeter‐wave applications

AbstractThis letter proposes an ultra‐wideband planar patch antenna array in a millimeter wave (mmW) band. The radiation element consists of a pair of symmetrical E‐shaped patches and two pairs of grounded metallic vias. A microstrip line is selected to excite the antenna element through an H‐shaped coupling slot. The entire structure is designed on two substrates, which makes it have a relatively low cost. The periodic boundaries are adopted in element simulation to achieve good agreement of performances between the element and the final array. The proposed element exhibits triple‐resonant characteristics and achieves a working bandwidth of 62%. By employing the proposed element, an 8 × 8 array with a 1‐to‐64 full‐corporate feeding network is designed, manufactured, and measured. The measured results demonstrate that the fabricated array prototype realizes an impedance bandwidth of 71% from 22 to 46.3 GHz covering all 5G mmW bands in the K/Ka band, a gain from 18.2 to 23.4 dBi over the whole operating bandwidth, and cross‐polarization levels below –30 dB. With the merits of an ultra‐wideband, stable radiation, and a low cost, the proposed array can be applied to long‐distance mmW communications and related applications.

An efficient technique to realize low‐profile dual‐band multi‐polarized shared‐aperture slot antenna array

An efficient technique to realize dual-band multi-polarized shared-aperture slot antenna array is proposed in this paper, featuring in all-metal, low-profile, light-weight and high radiation efficiency. The cavity-backed longitudinal slots are used at L-band for vertical polarization, while horizontal and vertical polarizations are both achieved at C-band, by utilizing interleaved ridged waveguides with two different kinds of slots. A coaxial-feed end-grounded metallic bridge is developed to excite the L-band cavity-backed slots, so the volume and weight of the L-band cavity can be obviously reduced. To further make the whole antenna structure compact and tight, the reduced L-band cavity is embedded into the serration, surrounding by two adjacent C-band ridged waveguides for vertical polarization and one for horizontal polarization. An array prototype, which consists of two L-band single-polarized antennas and four pairs of C-band dual-polarized antennas, is fabricated and measured. Experimental results are well consistent with the simulated ones, showing a satisfying impedance bandwidth of 12% in L-band and 5.5% in C-band, and besides high radiation efficiency above 85% for both bands. The all-metallic structure of this proposed array provides the thermal and mechanical advantages for space-borne synthetic aperture radar (SAR) application.

Beyond the phantom: Unroofing the scala vestibuli in a fresh temporal bone as a model for cochlear implant insertion experiments

• Testing of new cochlear implant electrode array prototypes and/or insertion techniques is typically performed in transparent synthetic models, or via retrospective analysis of insertions performed in cadaveric temporal bones. • Standard cadaveric models for benchtop testing of cochlear implant electrode arrays are currently limited in their ability to directly visualize the EA during insertion experiments. • Uncapping the scala vestibuli in a cadaveric temporal bone allows for direct visualization of the cochlear implant electrode array during insertion while preserving the native tissue architecture of the scala tympani. • This model provided excellent direct visualization of electrode array behavior in four insertion scenarios, both manual and robotic. • This technique can be used for real-time analysis of electrode array insertion, enabling a better understanding of electrode array dynamics when testing new insertion techniques, tools, and designs.