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Summary: A compact, flexible, low‐profile end‐fire broadband wearable antenna operating in Ku‐band /X‐band is proposed in this manuscript for defense and satellite communications (Satcom) applications. The main objective of this work is cross‐polarization reduction by the defected ground structure (DGS), which offers a wider bandwidth. Due to its flexibility and ability to absolutely conform to the curved‐shaped human body, denim fabric is used as a substrate, whereas copper tape is used as a conductor, which allows for the integration of the antenna into garments and makes it appropriate for a wide range of wearable applications in various bands. The prototype has been developed with a size of 20×20×0.5 mm3 for experimental validation. The measured results from a fabricated prototype are well matched with the simulated ones of the proposed design, which indicate a wide bandwidth of 57.35% (7.76–14 GHz) appropriate for use in applications such as defense operating from 8 to 12 GHz, satellite TV (11.7–12.2 GHz), Ku‐band downlink (10.95–11.7 GHz), Ku‐band uplink (11.7–14.5 GHz), and a high gain of 5.1 dBi. The specific absorption rate (SAR) is much below the permissible limit of 1.6 W/kg, with better radiation characteristics. Thus, the proposed antenna is more compact, and it clearly achieves a smaller footprint, larger impedance bandwidths, and a low SAR with potential prospect for Satcom and defense purposes. [ABSTRACT FROM AUTHOR]

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This paper analyzes broadband antennas, with a special focus on Vivaldi antennas, for their suitability for through-wall radar applications. It assesses various antenna designs, emphasizing high gain, wide impedance bandwidth, and effective wall penetration capabilities. Vivaldi antennas are superior due to their broad bandwidth, high gain, and directional radiation patterns. This study further explores structural optimizations, feeding techniques, and performance enhancement strategies to refine Vivaldi antenna designs for through-wall radar systems. Through a comparative analysis and technical evaluation, this paper highlights Vivaldi antennas' potential for improving through-wall radar systems' imaging and sensing capabilities. This presents a pathway for future ultra-wideband advancements. [ABSTRACT FROM AUTHOR]

This paper proposes and analyzes a 2 × 2 multi‐input multioutput antenna based on an open‐loop resonator structure and an inverted L structure. The top layer of the antenna uses symmetric inverted hook‐shaped and inverted L branches and is connected to the bottom layer of the dual‐feed port and the ground plane using the VIAs, respectively. The open‐loop resonator structure at the bottom of the antenna and the top layer of the branched circuit are resonated to provide wide‐bandwidth and dual‐frequency characteristics. The substrate uses FR4 with an area of 40 × 30 × 0.8 mm3. Although the two antenna feed ports are very close to each other, using via to connect the defective bottom ground structure and the top inverted L‐shaped branch, the isolation still achieves an excellent performance of 15 dB. The antenna has multiband application characteristics, and the bands include 2.29–5.51, 6.14–10.26, 2.29–5.33, 5.19–6.64, and 6.78–10.16 GHz. In pattern and MIMO transmission efficiency measurement, the peak radiation efficiency is 89%, the peak gain is 8.5 dBi, and the ECC is less than 0.034. In the transmission efficiency measurement mode using 64‐QAM, watching the error vector magnitude at 2.56 and 5.11 GHz, the demodulation effect is very good, and the respective throughput results are 100% and 79.2%. The broadband characteristics of the antenna have a variety of applications, and it is simulated at the specific absorption rate, which meets the standards set by the Federal Communications Commission and is very suitable for use in wearable devices. The antenna can be applied to the X‐band, n77, n79, Sub‐6 GHz, WiMax, DSRC, WiFi 6, WiFi 6E, WiFi 7, C‐V2X, and C‐band. [ABSTRACT FROM AUTHOR]

This paper proposes a 10 × 10 MIMO multiband broadband planar antenna for tablets or laptops. The designed antennas cover a large number of the popular sub‐6‐GHz application bands, such as 0.617–0.96, 2.1–2.7, 3.5–4.5, and 6.1–7.2 GHz for public safety communications, radio systems, Bluetooth, Wi‐Fi, and satellite communications. The proposed antenna is designed with grounded branches, which can generate a wide bandwidth and cover most of the sub‐6‐GHz application band by coupling between branches of different lengths and antennas. MIMO antennas have been measured to have an envelope correlation coefficient of less than 0.7 and have met the standards set by international organizations for human radiation absorption simulations. The proposed antenna validates the unique 10 × 10 MIMO antenna structure and feasibility. Multiple operable frequency bands are realized, and the radiation effect of the antenna on the human body is analyzed if it complies with international market standards. The proposed antenna design is well suited for multiband and broadband requirements. [ABSTRACT FROM AUTHOR]

Summary: A broadband ±45° dual‐polarized omnidirectional array with small size is presented. A crossed‐arranged dipole element is proposed to generate a wide unidirectional radiation beam. A crossed‐arranged parasitic strip is used to dramatically widen the impedance bandwidth of the dipole element. Based on the dipole element, a rotational two‐unit subarray, which comprises a small number of dipole elements and occupies a small space, is originally proposed to generate excellent omnidirectional radiation performance. Then a four‐unit array with a simple feed network is designed based on the rotational subarray. The array obtains a wide bandwidth of 59.4% (1.55–2.86 GHz) for reflection coefficient <−10 dB and an isolation beyond 21 dB between the two polarizations. Meanwhile, a very low gain variation of below 3 dB, as well as a stable and high realized gain of 5.1 ± 0.5 dBi are achieved over the operating band. [ABSTRACT FROM AUTHOR]

This paper presents a broadband high-isolated MIMO antenna operating in the C and X bands simultaneously. The antenna is expected to be applied in wireless systems such as satellites and radar. A modified Vivaldi element is firstly designed by etching a rectangular structure out of the top metal, and then arranged symmetrically to form a 2-element broadband MIMO antenna with element spacing of 0.28λ (λ is the wavelength at 9 GHz). The operating frequency the MIMO antenna in terms of S11 ≤ −9.0 dB is from 4.0 GHz to 13.5 GHz. However, the mutual coupling between the two elements is quite strong, which can be as high as 8.0 dB, indicating a severe mutual coupling effect between the elements. To improve the isolation level, a defect-ground structure (DGS) is designed and loaded on the ground plane. The decoupling structure of the DGS achieves decoupling in the C and X bands, with a particular emphasis on decoupling in the C band by blocking the current flow between antenna elements. The simulated result shows that the S21 can be lowered to less than −23.4 dB across the whole operating frequency region, i.e., an isolation improvement of 15 dB is achieved. A prototype is fabricated and measured. The measured results are in good agreement with the simulated ones, indicating that the designed broadband MIMO antenna is a good candidate for reliable communication in the C and X bands. [ABSTRACT FROM AUTHOR]

In this paper, a wideband wide-beam circularly polarized (CP) antenna excited by sequential rotation feeding technology is proposed. The antenna is primarily constituted of a loop radiating element and a reactive impedance structure (RIS) cavity. The loop radiator is stimulated by a curved feeding line through six slots etched on the ground, thereby enabling the antenna to achieve broadband performance. In order to achieve a wide 3-dB axial-ratio beamwidth (ARBW), as well as exhibit less effect on the half-power beamwidth (HPBW), a RIS cavity is introduced beneath the loop radiator. To validate the proposed structure, a prototype was constructed and subjected to a series of tests. The results indicate that the bandwidth of the antenna is 187.5% (0.11 ∼ 3.41 GHz) under a 10-dB return loss. In the frequency band spanning from 1.07 GHz to 2.1 GHz, the AR is less than 3 dB, yielding a bandwidth of 64.98%. Furthermore, at the frequencies of 1.2 GHz, 1.5 GHz, and 1.8 GHz, the proposed antenna demonstrates wide beam characteristics, with the HPBW exceeding 90◦, and the 3-dB ARBW within 162◦ 224◦ . In addition, since no extra feeding network is utilized, the antenna is compact in size. [ABSTRACT FROM AUTHOR]

Summary: In this research work, a compact‐sized offset‐fed broadband monopole antenna is designed using a frequency selective surface (FSS) reflector to enhance gain, radiation efficiency, and FBR and validated experimentally. The designed antenna consists of a triple v‐slit on a rectangular‐shaped radiating patch, a modified partial ground, and a frequency‐selective surface (FSS). It exhibits a ‐10 dB impedance bandwidth of 9.37 GHz (6.55–15.92 GHz) and a fractional bandwidth of 83.4%, yielding significant portions of the C‐band (4–8 GHz), the X‐band (8 GHz–12 GHz), and covering a considerable part of the Ku‐band (12–18 GHz). The proposed prototype equivalent circuit model has been developed progressively to validate the electromagnetic simulation results. The measured peak gain is 14.25 dBi (6.8 dBi without FSS) at 14.2 GHz with an average radiation efficiency of ≥ 96% for the FSS integrated antenna. Furthermore, the proposed design improves the front‐to‐back ratio (FBR) by 15 dB throughout the broadband frequency range. The proposed antenna peak gain, reflection coefficient (S11), radiation efficiency, and radiation patterns show adequate similarity between the tested and simulated results and have numerous advantages, including very compact size, simple structure, minimum S11 (dB), high gain, and broadband capability. [ABSTRACT FROM AUTHOR]

A wideband polarization-reconfigurable microstrip antenna based on a mode-fusion mechanism is proposed. This simple antenna structure consists of a rectangular radiation patch and a ground, both with crossed slots. The slots crossing the ground are connected by eight PIN diodes and four capacitors such that two orthogonal linear-polarization radiation modes can be realized. The radiation patch is slotted such that a transformed TM 20 mode is excited, realizing broadside radiation that the traditional TM 20 mode is unable to. With fusion of the fundamental TM 10 mode and the transformed- TM 20 (T- TM 20 ) mode, a wide bandwidth of 30.1% is achieved in two reconfigurable polarizations. The measured results agree well with the simulation results. The total efficiency of the proposed antenna is more than 80.0% over the bandwidth. [ABSTRACT FROM AUTHOR]

\nPlain-language summaryMicrowave applicators reported for intracavitary hyperthermia (HT) operate at single frequency and deliver fixed treatment coverage at the tumor target. In this work, we report multifrequency operation of a water-cooled monopole antenna with a sliding broadband ferrite choke for delivering intracavitary HT to the cervix with variable spatial coverage. Spatially varying treatment coverage is achieved by varying the choke position with respect to the monopole using a mechanical sliding arrangement and exciting the antenna at the modified resonant frequency. Multifrequency operation of the antenna prototype is demonstrated over 700–1000 MHz using a straight intrauterine cervix applicator. Numerical simulations confirm the ability to deliver targeted HT with axial extent varying between 35.4 and 62.0 mm by controlling the sliding choke and coupling water temperature. Applicator prototype measurements in tissue mimicking phantoms confirm multifrequency operation of the antenna and its ability to induce axially varying intracavitary HT coverage to match the tumor size using a single applicator.Microwave devices used for targeted internal hyperthermia treatment typically operate at fixed frequency and provide fixed treatment coverage to the tumor. In this study, we introduce a new approach using a water-cooled monopole antenna with a sliding broadband ferrite choke to treat cervical cancer with varying tumor volumes. The proposed antenna can be operated at multiple frequencies to adjust the treatment volume. By sliding the choke along the antenna, the antenna can be tuned to different frequencies and deliver spatially varying treatment coverage to suit the clinical target volume. Laboratory assessment shows that this antenna can be operated over 700 to 1000 MHz to deliver treatment coverage with axial extent varying over 35.4 to 62.0 mm, depending on the choke position and water temperature. Experiments on tissue mimicking phantoms confirm that this method enables precise control of hyperthermia treatment coverage to match the tumor size using a single device. [ABSTRACT FROM AUTHOR]

Toroidal electromagnetic pulses have been recently reported as nontransverse, space-time nonseparable topological excitations of free space. However, their propagation dynamics and topological configurations have not been comprehensively experimentally characterized. In addition, the existing generators were limited in optical and terahertz domains; however, the feasibility and significance of generating such pulses at microwave frequencies have been overlooked. Here, we report that microwave toroidal pulses can be launched by a transient finite-aperture broadband horn antenna emitter, as an electromagnetic counterpart of "air vortex cannon." Applying this effective generator, we experimentally map the toroidal pulses' topological skyrmionic textures in free space and demonstrate their resilient propagation dynamics, i.e., how that, during propagation, the pulses evolve toward stronger space-time nonseparability and closer proximity to the canonical Hellwarth–Nouchi toroidal pulses. Our work offers a practical opportunity for using topologically robust toroidal pulses as information carriers in high-capacity telecom, cell phone technology, remote sensing, and global positioning, especially where microwave frequencies are predominant. [ABSTRACT FROM AUTHOR]

This paper presents the design details of an integrated 4x4 element dual feed dual circularly polarized microstrip antenna array in the S-band. The dual circular polarization is achieved by the use of quadrature hybrids. Power division for the dual input array is achieved through two 1x16 equal split equal phase corporate feed networks. The quadrature hybrids and corporate feeds for the proposed array are designed in multilayer printed circuit boards (PCB) in stripline configuration. This antenna can be used to transmit or receive both right-handed circularly polarized (RHCP) waves or left-handed circularly polarized (LHCP) waves simultaneously or one at a time by terminating the other port with 50Ω resistance. The proposed antenna has 700MHz of 10 dB impedance bandwidth (27%), 400MHz of 3dB axial ratio bandwidth and 300MHz of 3dB gain bandwidth centred at 2.5GHz with a peak gain of 15.5dB in both polarizations. It has a 3dB beam width of 26° and cross-polarization levels below 20dB in both the polarizations. Design and simulation of patch array, quadrature hybrids and 1x16 corporate feeds in multilayer configuration, PCB stack-ups, fabrication, integration and testing processes are discussed in detail. The effect of thermal protection system (TPS) of the re-entry vehicle on antenna performance parameters was studied and presented. [ABSTRACT FROM AUTHOR]

In this paper, a novel method for detecting breast cancer utilizing an ultra-wideband (UWB) microstrip patch antenna operating in the UWB frequency range is presented. The promise of non-invasive, radiation-free breast cancer screening is provided by UWB technology. We give a brief overview of the difficulties in detecting breast cancer as well as the benefits of UWB technology in medical applications in this study. This study presents a compact printed microstrip patch antenna used for the bio-medical application at industrial, scientific, and medical (ISM) and UWB frequencies. The proposed antenna consists of a hexagonal-shaped microstrip patch antenna with a slotted ground antenna used for high bandwidth for a wider range of applications. The compact biomedical antenna is printed on Roger 5880 substrate with an overall dimension of 25*25 mm. Due to the high demand for results accuracy, Roger 5880 substrate material is used because it has good dielectric characteristics and loss factors that are appropriate for medical and radio frequency (RF) applications. A 50-ohm impedance line is used to feed the antenna. The proposed antenna has a higher bandwidth of almost 12.5 GHz at such a low frequency, starting from 3.53 to 16 GHz. The antenna has an acceptable gain of 3.38 Db, which is enough for the required application. The UWB microstrip patch antenna has the potential to improve breast cancer detection accuracy and reliability, which would aid in early diagnosis and better cancer patient treatment. This work represents a major advancement in the development of non-invasive, low-cost breast imaging methods for early cancer diagnosis. [ABSTRACT FROM AUTHOR]

In this study, we propose a compact broadband conformal array antenna using artificial dielectric slabs. The proposed antenna consists of three artificial dielectric slabs with a linear impedance distribution stacked on a bow-tie slot antenna. This enables an efficient impedance transition across a wide band from the slot to free space. Each slab is implemented using a sub-wavelength square patch array, achieving a 3:1 bandwidth from 6∼18 GHz. The height of the proposed antenna is 8.24 mm (0.165λ6GHz), with an array distance of 8.33 mm (0.5λ18GHz). The conformal array was designed with a curvature of 27.79° in the H plane. Simulation results show that the proposed antenna maintains an active S-parameter below -10 dB across the target bandwidth and achieves a boresight gain of -4.88 dBi at 6 GHz and 4.8 dBi at 18 GHz. To validate its performance, eight 8×1 arrays were fabricated, combined in the E-plane with a corporate feeding network, and mounted on a curved metallic surface. The measurement results of the fabricated array confirmed that the active S-parameter remained below 10 dB across the target bandwidth. Additionally, post-processing of the measured active element patterns generated beam-steering patterns with a maximum error of 3°. [ABSTRACT FROM AUTHOR]

Plasmonic nanoantennas with suitable far-field characteristics are of huge interest for utilization in optical wireless links, inter-/intrachip communications, LiDARs, and photonic integrated circuits due to their exceptional modal confinement. Despite its success in shaping robust antenna design theories in radio frequency and millimeter-wave regimes, conventional transmission line theory finds its validity diminished in the optical frequencies, leading to a noticeable void in a generalized theory for antenna design in the optical domain. By utilizing neural networks, and through a one-time training of the network, one can transform the plasmonic nanoantennas design into an automated, data-driven task. In this work, we have developed a multi-head deep convolutional neural network serving as an efficient inverse-design framework for plasmonic patch nanoantennas. Our framework is designed with the main goal of determining the optimal geometries of nanoantennas to achieve the desired (inquired by the designer) S11 and radiation pattern simultaneously. The proposed approach preserves the one-to-many mappings, enabling us to generate diverse designs. In addition, apart from the primary fabrication limitations that were considered while generating the dataset, further design and fabrication constraints can also be applied after the training process. In addition to possessing an exceptionally rapid surrogate solver capable of predicting S11 and radiation patterns throughout the entire design frequency spectrum, we are introducing what we believe to be the pioneering inverse design network. This network enables the creation of efficient plasmonic antennas while concurrently accommodating customizable queries for both S11 and radiation patterns, achieving remarkable accuracy within a single network framework. Our framework is capable of designing a wide range of devices, including single band, dual band, and broadband antennas, with directivities and radiation efficiencies reaching 11.07 dBi and 75 %, respectively, for a single patch. The proposed approach has been developed as a transformative shift in the inverse design of photonics components, with its impact extending beyond antenna design, opening a new paradigm toward real-time design of application-specific nanophotonic devices. [ABSTRACT FROM AUTHOR]

This paper demonstrates the design, modeling, and analysis of a small size 180 × 165 × 1.6 mm3 printed broadband Vivaldi antenna for electromagnetic compatibility measurements. The proposed antenna is intended to be utilized as a reference antenna for emission and immunity tests inside the EMC Chamber through the band (0.8–5.5 GHz). Exponentially tapered slots were created based on mathematical equations to form an end-fire radiation antenna. Furthermore, microstrip and slot line stubs were employed to tune the impedance bandwidth. This antenna could be considered a 2-D Horn antenna with a size reduction of 64% and 67% since both antennas, Vivaldi and Horn are based on the same principle. Two rectangular slots were engraved near the feeding point to reshape and enhance the gain at lower frequency bands. Furthermore, the realized gain has been improved by approximately 3.5 dB and reached up to 10.7 dBi by introducing a pair of triangular reversal slots at the top edges of the structure. Moreover, this antenna has specifications that make it a suitable candidate to work as a reference antenna inside the EMC chamber compared to the classical Horn antenna offered for sale (PowerLOG® PRO 30800 and TBMA4). [ABSTRACT FROM AUTHOR]

In this paper, a MIMO antenna with broadband circular polarization is designed in a single‐layer substrate for the next‐generation Wi‐Fi 7 applications. The top of the substrate is designed with a periodic array of 5 × 5 circle patches and orthogonally placed four L‐shaped aperture CPW feeds on the bottom face of the substrate are used to feed the patches. The stubs are arranged across the apertures to achieve a broad bandwidth. The array of patches is used to achieve high gain over resonant frequency range and L‐shaped apertures are used to achieve circular polarization. The designed antenna with the above specifications has gained an impedance bandwidth of 20.4% (5.37–6.59 GHz), a 3 dB axial ratio bandwidth over the entire resonant frequency range of 25.61% (5.14–6.65 GHz) and a peak gain of 8.5dBi. [ABSTRACT FROM AUTHOR]

In this research paper, the authors propose a unique broad-band circularly polarised antenna design with a sequentially rotated feed network intended for applications in the WiMAX IEEE 802.16, C-band, and ITU-R F386.9 bands. A sequential feeding approach utilising transmission lines with varying impedance properties and lengths has been utilised to properly stimulate the amplitude and phase distribution of each radiation element. To facilitate the rotation of the surface current distribution on the ground plane and further improve impedance matching, four L-shaped slits have been inserted into each corner of the ground plane along with a pair of mirrored slits of identical geometry within the antenna ground plane. The individual antenna element achieves an impedance bandwidth between 5–6.8 GHz and a 3 dB axial ratio bandwidth from 5.1–6.6 GHz. To additionally advance the radiation performance, the elements are configured into a 2 × 2 antenna and are interconnected utilising a sequentially rotated feeding network to attain broader axial ratio and impedance bandwidths. A key benefit of the implemented feed network is the minimisation of coupling effects between elements. To significantly increase the performance metrics of the antenna with limited increase to its physical size, electromagnetic band gap structures were incorporated as a one-dimensional lattice between the radiating elements. For the resulting antenna, an axial ratio bandwidth from 4.19 to 6.8 GHz (48%) and an impedance bandwidth spanning 2.9 to 9.8 GHz (102%) are achieved. The peak gain of the antenna is 11.2 dBic. [ABSTRACT FROM AUTHOR]

This article proposes a dual mode dual-polarized antenna configuration for IRNSS and fifth generation (5G) applications, operating at a frequency of 3.5 GHz based on characteristic mode analysis (CMA), and aims to provide broadband dual-polarized functionality. The original design of the antenna is a traditional patch antenna, and its dual-polarized features are determined using characteristic mode analysis. The full-wave method is used to stimulate both orthogonal modes using a 50 Ω coaxial input line at 3.5 GHz. In this design, the circular patch has been extended into an elliptical patch through a process of mode separation. The circular patch exhibits resonance at a frequency of 2.5 GHz, whereas the extended elliptical radiator demonstrates two resonance modes at 2.5 GHz and 3.5 GHz. The operational mechanism is elucidated by modal analysis and characteristic angle. This antenna operates on two different frequencies at the 2.5 GHz IRNSS band with horizontal polarization and the 3.5 GHz 5G service with vertical polarization. The maximum gain achieved with these frequency ranges is 5.31 dBi and 4.72 dBi, respectively. A ring resonator is chosen to improve the axial ratio and impedance bandwidth of the suggested prototype. The antenna's ground plane is shaped like a rectangle and features a V-shaped slot in the radiating patch. The antenna's physical footprint is 50 mm × 50 mm × 1.6 mm and an FR4 dielectric substrate serves as its foundation. Through its interaction with a PIN diode, the diode modifies the polarization of the antenna. The antenna functions as a right-handed circular polarization (RHCP), when the diode is operational. The bandwidth from 4.3 to 7.5 GHz is covered. On the other hand, it generates linear polarization (LP) between 4.2 and 5.3 GHz. The experimental antenna is evaluated and examined for its performance characteristics. The simulations are carried out utilizing the CST simulator. A prototype antenna has been manufactured and its performance has been validated against simulated findings. [ABSTRACT FROM AUTHOR]

In this paper, a low-profile and broadband array antenna is proposed for satellite downlink applications. The proposed antenna is comprised of 4 × 4 elements, which are yielded for the downlink of the C band from 3.7 to 4.8 GHz. By arranging frequency selective surface (FSS) unit cells according to a new architecture, high directivity and broadband are provided, in which each element is covered by a lattice of 3 × 3 periodic metal plates. Based on RO4350B, the final design with a total size of 180 × 180 × 3.175 mm3 (2.38λ × 2.38λ × 0.04λ at the lowest frequency of 3.97 GHz) has been fabricated, measured, and witnessed a broadband characteristic with S11 < −10 dB of 36% (3.97–5.5 GHz). In addition, the proposed antenna achieves a peak gain of 16 dBi and a radiation efficiency of 71%. [ABSTRACT FROM AUTHOR]

Assembling polarization conversion metasurface (PCM) and a simple patch antenna to realize a circularly polarized (CP) antenna with over 10% fractional bandwidth (BW) is a challenging task. A kind of PCM composed of S‐ring and grating structure that converts linearly polarized (LP) wave into CP wave in a broadband frequency from 8.74 to 12 GHz can address the challenge. The universality of the PCM in realizing antenna polarization conversion is verified by using a standard LP horn antenna. Then, we design a broadband LP rectangular patch antenna to demonstrate that the present PCM can be integrated with small antenna devices to achieve CP antenna. A broadband CP patch antenna with a 12.4% −10 dB BW and 11.3% 3 dB axial ratioBW is obtained. The antenna gain reaches 8.1 dB with the enhancement gain of 4.1 dB. The findings are very attractive for wireless communication, radar monitoring, and satellite systems because the proposed antenna has excellent broadband CP performances, simple structure, and easy fabrication. [ABSTRACT FROM AUTHOR]

Lens antenna-coupled detectors have emerged as a prominent technology for millimeter-wave astronomy over recent decades. The future ground-based cosmic microwave background (CMB) observations that target B-modes require the receiver to operate across multiple frequency bands while maintaining effective polarization selectivity. In this context, we have reconfigured the conventional broadband bowtie slot antenna into a dual-flare angle design, exclusively targeting the CMB emission wavelength at two bands centered at 150 GHz and 220 GHz. This antenna design facilitates partial independent tuning of resonant frequencies, leading to improved impedance-matching bandwidth,that achieves a return loss of ( S 11 < - 10 dB) spanning over an octave from 100 to 300 GHz. Simultaneously, it maintains effective linear polarization sensitivity, with cross-polarization remaining below −15 dB at both sub-bands when coupled with a dielectric lens. The integration of on-chip band-pass filters enables the effective separation of antenna signals to microwave kinetic inductance detectors. This results in a compact, polarization-selective, multichroic pixel solution that perfectly aligns with the demands of CMB B-mode observation. [ABSTRACT FROM AUTHOR]

This article presents a novel multiprobe planar near-field range (PNFR) measurement system. The said system simplifies the overall mechanical design, making it simpler than the existing scanning probe PNFR measurements, and also significantly reduces testing time. A dielectric-based probe is introduced to reduce the antenna size, thereby improving resolution. The probe under consideration is an antipodal Vivaldi antenna offering broadband support and ensuring wideband characteristics of aerials. Numerical results for representative X-band antenna models, presented in the Matlab environment, demonstrate robust performance of the developed measurement system. [ABSTRACT FROM AUTHOR]

In this paper, a broadband bowtie-based log-periodic array antenna is proposed and investigated for 5G millimeter wave (mmwave) applications. Using a Glass Integrated Passive Device (GIPD) process the proposed antenna is implemented on a high dielectric constant glass substrate. To address the directional radiation issues associated with the traditional straight connection, the proposed antenna uses a crisscross connection effect with carefully spaced three dipole elements. Furthermore, the use of bowtie-based dipole offers a wide bandwidth advantage. The study also examines the effects of changes in key parameters on critical antenna features. The feeding structure uses a combination of coplanar waveguide (CPW) and microstrip line to strip line. For demonstration, a prototype antenna is optimized, fabricated, and measured. The measurement results show that the 10 dB impedance bandwidth of the proposed antenna is from 21.5 to 36.1 GHz, and the gain is higher than 5.63 dBi. [ABSTRACT FROM AUTHOR]

Previous research in millimeter-wave antenna technology has focused on designs for specific frequency bands, such as 28 GHz, 32 GHz, 60 GHz, and 78 GHz. This paper analyzes an asymmetric dual-step antipodal petunia-shaped antenna capable of operating across the entire mm-wave frequency range from 30 GHz to 300 GHz. In the initial phase, a K-Band antenna is designed using various single radiators, including shapes such as a ball, balloon, axle, and petunia, in conjunction with a rectangular ground structure. A single radiator petunia design is enhanced to become a dual antipodal petunia radiator to achieve higher operating frequencies. This antipodal design generates multiple resonances at adjacent frequencies, resulting in broadband characteristics. To further improve performance, modifications are made to the ground structure. A novel technique inspired by radiation contouring of the antenna is proposed, which enhances impedance matching and overall antenna performance. Subsequently, a dual antipodal petunia radiator with an asymmetric step ground is optimized using the particle swarm optimization method to cover the entire millimeter-wave band (30-300 GHz). The antenna's physical dimensions are 30x30 mm², with a peak gain of 6 dBi and radiation efficiency ranging from 89% to 92% across the entire mm-wave spectrum. Notably, this proposed antenna exhibits an exceptionally low level of side lobes and excellent cross-polar discrimination, showcasing its unique design. The potential applications of this antenna span various fields, including military and imaging systems, automotive radar, telecommunications, remote sensing, security screening, and energy harvesting technology. [ABSTRACT FROM AUTHOR]

This research proposes a compact broadband circularly polarized (CP) corner-truncated microstrip antenna with irregularly hexagonal artificial magnetic conductor (AMC) for 2.45 GHz WLAN applications. The corners of the radiating patch are diagonally truncated to realize circular polarization and improve axial ratio. A 5▪5 irregularly hexagonal AMC array is employed to enhance the axial ratio bandwidth (ARBW) and antenna gain. In addition, a tri-section meandering feedline is used to realize impedance matching and improve the impedance bandwidth (IBW). The AMC array is used to manipulate electromagnetic waves by suppressing surface currents and back lobe, resulting in reduced back radiation and enhanced front-to-back ratio. The simulated IBW and ARBW are 50.9% (1.86 – 3.13 GHz) and 19.3% (2.24 – 2.72 GHz) respectively, with a maximum gain of 8.9 dBic at 2.45 GHz. The measured IBW and ARBW are 42.42% (1.95 – 3.0 GHz) and 29.4% (2.03 – 2.73 GHz), with a maximum gain of 8.6 dBic. The simulated half power beamwidth (HPBW) of the proposed antenna scheme in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 67°, 62°, and 51°, respectively. The corresponding HPBW in the yz plane are 60°, 55°, and 62°. The simulated AR beamwidth in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 177°, 164°, and 88°, respectively. The corresponding AR beamwidth in the yz plane are 148°, 106°, and 124°. The simulated cross polarized (XP) levels at 2.45 GHz are below -19.35 dB for both planes. The measured HPBW in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 69°, 64°, and 50°, respectively. The corresponding HPBW in the yz plane are 65°, 54°, and 37°. The measured AR beamwidth in the xz plane at 2.24 GHz, 2.45 GHz, and 2.72 GHz are 161°, 200°, and 104°, respectively. The corresponding AR beamwidth in the yz plane are 162°, 85°, and 90°. The measured XP levels at 2.45 GHz are below -15.62 dB for both planes. The radiation pattern is unidirectional. Essentially, the proposed broadband CP antenna scheme is suitable for the WLAN frequency band and other 2.45 GHz wireless communication technologies. The novelty of this research lies in the use of the tri-section meandering feedline and the irregularly hexagonal AMC array to enhance IBW and ARBW. • This research proposes a compact broadband CP corner-truncated microstrip antenna with irregularly hexagonal AMC for 2.45 GHz WLAN application. • The measured IBW and ARBW are 42.42% (1.95 – 3.0 GHz) and 29.4% (2.03 – 2.73 GHz), with a gain of 8.6 dBic. The radiation pattern is unidirectional. • The measured HPBW in the xz and yz plane at 2.45 GHz are 64° and 54°, respectively. The measured XP levels at 2.45 GHz are below -15.62 dB for both planes. • The proposed broadband CP antenna scheme is suitable for the WLAN frequency band and other 2.45 GHz wireless communication technologies. • The novelty of this research lies in trisection meandering feedline and the irregularly hexagonal AMC unit cells to achieve wider IBW and ARBW. [ABSTRACT FROM AUTHOR]

This paper simulates and measures a compact broadband rectifier for voltage doubler Schottky diode. Among them, a two‐stage microstrip line impedance matching network for voltage doubling circuits is used. The imaginary part of the diode impedance is limited by the short‐circuit branch. The impedance conversion transmission line matches the impedance to 50 Ω. The impedance matching in the circuit is only realized by two‐stage microstrip lines, which reduces the physical size of the rectifier and makes the rectifier more compact. Judging the measurement results from 0.8 to 2.5 GHz, the conversion efficiency is greater than 30% at 0 dBm, the bandwidth is 103%, and the maximum conversion efficiency reaches 66.3% at 8 dBm. In addition, the compact size of the rectifier is 23 × 20 mm2. [ABSTRACT FROM AUTHOR]

Summary: The proposed antenna is a small wideband monopole with wideband circular polarization using heterogeneous bidirectional recurrent neural network for both narrow and wide band applications (NWB‐MAD‐HBRNN). The electromagnetic structure is designed, fabricated, and simulated with 1 mm thickness on FR4 substrate material along dielectric constant 4.3. The proposed antenna includes 4.3–8.85 GHz for ultrawideband applications; it contains reconfigurable narrow band for L‐band 1.27 GHz, LTE, and ultrawideband applications. To enhance the antenna impedance bandwidth (BW) along axial ratio bandwidth (ARBW), a slit is etched at the antenna patch, a rectangular stub is inserted into the ground plane, and semicircular stub is added to the top of antenna feed line. The better agreement is observed in the measured and simulated gain performance of 4.8 dB for LTE band applications. The proposed NWB‐MAD‐HBRNN design provides 13.50%, 18.91%, and 22.58% higher bandwidth and 18.36%, 20.38%, and 27.58% lower return loss than the existing designs, such as bio‐inspired wideband antenna for wireless applications based on perturbation technique (BWA‐WA‐PA), a compact circularly polarized modified printed monopole antenna for wireless applications (CCP‐MPMA‐WA), and new multiband monopole antenna for certain broadband wireless applications along wireless personal communications (PA‐MMA‐BWA), respectively. [ABSTRACT FROM AUTHOR]

We propose a method for increasing the bandwidth of a substrate‐integrated‐waveguide (SIW) cavity‐backed antenna with taper‐based microstrip SIW transition feeding. For radio transmission, a circular slot is etched on top of the SIW cavity. For optimal antenna design, the slot is etched slightly away from the cavity center to generate circularly polarized waves. Simulations show a wide axial ratio bandwidth of 7.860% between 11.02 GHz and 11.806 GHz. Experimental results confirm a similar wide axial ratio bandwidth of 4.9% between 10.8 GHz and 11.35 GHz. An SIW feed from an inductive window excites the radiating circular slot, resulting in a simulated wide impedance range of 1.548 GHz (10.338 GHz–11.886 GHz) and bandwidth of 13.93%. Experimental results show a wide impedance of 2.08 GHz (10.2 GHz–12.08 GHz) and bandwidth of 18.84%. The SIW cavity‐backed antenna creates a unidirectional pattern, leading to gains of 6.61 dBi and 7.594 dBi in simulations and experiments, respectively. The proposed antenna was fabricated on a Rogers RT/Duroid 5880 substrate, and the reflection coefficient, radiation patterns, and gains were tested and compared using a computer simulator. The developed broadband antenna seems suitable for X‐band applications. [ABSTRACT FROM AUTHOR]

In this manuscript, we propose a circularly polarized (CP) antenna design that can achieve broadband axial ratio (AR) bandwidth in the X-band. A sequentially rotated serial feeding network is applied to achieve the broadband requirement. The proposed antenna consists of two substrates, one is for feeding elements and the other is for radiating elements. The 16 radiating elements located on an upper substrate are fed through cross-shaped slots located in a ground plane between two substrates. The feed network is based on a 1:4 power divider design and consists of a serial connection of the power dividers resulting in the proper power splitting to the 16 radiating elements. The proposed antenna is designed to exhibit an optimal radiation characteristic of around 8.2 GHz with a CP antenna gain greater than 16 dB and similarly wide impedance and AR bandwidths. Experiments with the fabricated CP antenna were performed to support the proposed CP antenna design theory and are in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

The presented research aims to analyze in detail the characteristics of broadband matching antennas specifically designed for 5G mobile communications applications, with an emphasis on innovative composite materials. The study focuses on a compact planar loop antenna designed for use on smartphones, covering the LTE/WWAN frequency bands 824 to 960 MHz, 1,710 to 2,690 MHz, and 3,300 to 3,600 MHz for full coverage of modern 5G networks. Experimental and numerical methods are used to broadly analyze the frequency range associated with 5G networks. The features of the use of composite materials in the implementation of antenna devices in 5G technologies are noted. A broadband matching circuit (BMC) with elements with lumped parameters and a reduced sensitivity invariant has been synthesized. A 3D model of the adaptive selective surface controller (SSC) was developed using CST Studio. The study results highlight the benefits of new composite materials in improving the performance of 5G antennas. This research makes a significant contribution to the development of 5G technologies by optimizing antenna design for efficient data transmission in modern mobile networks and can be a valuable resource for engineers and designers working in this field. [ABSTRACT FROM AUTHOR]

In this paper, a novel input impedance analysis methodology based on Babinet's principle to broaden bandwidth is proposed, and a broadband multiple-input and multiple-output (MIMO) antenna system is designed, fabricated, and measured for fifth-generation (5G) and Wireless Fidelity (Wi-Fi) 6E/7 mobile applications. By analyzing the input impedance of open-slot antennas and planar monopole antennas using numerical calculations, the characteristics of the input impedance can be obtained. We find that combining the two antenna types in parallel can significantly enhance the bandwidth. Then, the four-dimensional image calculated by MATLAB based on the parallel impedance formula is processed to validate the methodology. Thus, a broad antenna element based on the impedance property analysis methodology is achieved, which operates ranging from 2.6 GHz to 7.46 GHz. Moreover, the equivalent circuit of the antenna element is established to further verify the validity of the methodology. Finally, a broadband MIMO antenna system consisting of eight antenna elements is designed, fabricated, and measured, and the isolation performance is better than 12 dB. Acceptable total efficiency higher than 45% is also obtained with envelope correlation coefficients (ECCs) lower than 0.05. The proposed impedance property analysis methodology innovatively proposes a new way to increase bandwidth, which can be widely applied in various antenna designs. Also, reasonable results show that the proposed MIMO antenna system is a good candidate for 5G and Wi-Fi 6E/7 mobile applications. [ABSTRACT FROM AUTHOR]

Abstract This article introduces a novel, single‐layer, low‐profile, circularly polarized metasurface antenna. Through characteristic mode analysis, the optimization of a 3×3 rectangular metasurface structure was performed. Two orthogonal modes were selected as the operating modes, and improvements to the metasurface structure were made to achieve a 90∘ phase difference between these modes. The adoption of a coplanar waveguide structure enables the excitation of the metasurface, facilitating circularly polarized radiation performance for the two selected modes. The antenna's dimensions are 40 mm × 40 mm × 3 mm (0.67 λ × 0.67 λ × 0.05 λ), featuring a −10 dB impedance bandwidth of 27.8% (4.49–5.94 GHz). The 3 dB axial ratio bandwidth is 14.2% (5.25–6.05 GHz), with a maximum gain of 7.26 dBi.

Abstract Ever‐increasing bandwidth requirements from various industries drive the need for the ever‐increasing bandwidth of antennas used for testing. Broadband Double‐Ridged Guide Horn (DRGH) antennas are used extensively in antenna measurement and ElectroMagnetic Compatibility/Interference (EMC/I) testing. The current state‐of‐the‐art broadband DRGH antennas reported in the literature for use in measurement applications cover bandwidth ratios as large as 36:1 (0.5–18 GHz). This paper presents the design and realisation of a DRGH antenna with a 100:1 bandwidth ratio (0.5–50 GHz). To achieve such a wide bandwidth, the ridge gap, width and feed were optimised, and a novel coaxial‐to‐ridge waveguide launcher section based on a typical Vivaldi antenna was developed. Backward radiation was reduced using an absorber‐filled cavity. A prototype DRGH antenna was manufactured using additive manufacturing, also referred to as 3D printing. Simulated and measured results obtained in an anechoic chamber are presented.

A multiresonance metasurface antenna for C-band application is proposed in this paper. A broadband metasurface with consistent radiation performance is designed using characteristic mode analysis (CMA). The metasurface is formed by 4 × 4 square patches, and circular slots of different radius are etched on the center and edge patches. To achieve consistent radiation, the size of circular slots on the corner patches is increased. The metasurface is excited by slot antenna, and multiple adjacent resonant frequencies are generated by combining two modes of the metasurface and resonant mode of slot antenna. The measured results show that the −10 dB impedance bandwidth of the antenna is 4.22–8.38 GHz (66%), and the peak gain is 8.2 dBi. [ABSTRACT FROM AUTHOR]

A four-port low-profile broadband patch antenna is designed for fifth-generation (5G) multi-input multi-output (MIMO) mobile applications. The designed antenna loads shorting pins S1 and S2 on a square patch with etched fan-leaf slits, making the parasitic patch work more visible. In addition, loading shorting pin S3 excites a low-frequency resonant mode, which enables the antenna to completely cover frequency ranges of 3.3–5 GHz (5G N77 and N79 bands). The effective height of the designed antenna is only 3.7 mm (0.05λ at 4.15 GHz). The antenna achieves a good balance between impedance bandwidth and profile, realizing wide bandwidth coverage. To confirm the precision of the results, the designed antenna is fabricated and measured. The measured results show that the −6 dB impedance bandwidth covers 3.3–5 GHz. All the isolation between ports are superior to 12 dB. The envelope correlation coefficients (ECCs) is below 0.15 and the overall efficiency is between 50% and 90% in the 3.3–5 GHz. [ABSTRACT FROM AUTHOR]

This paper investigates various array beam shapes for high-power electronic warfare applications using an actual broadband array antenna. For use in a limited mounting space, a compact printed log periodic dipole array (LPDA) operating over a wide bandwidth is designed. The LPDA is then extended to an 8 × 1 array, with active element patterns (AEPs) obtained through simulation and measurement. Beam synthesis is performed by the superposition of several array patterns, which involves adjusting the weight of each AEP. To derive a synthesized array beam shape that is similar to the guided mask, the Taylor window weighting method is applied to each array pattern. Finally, beam synthesis for the flat-top beam, cosecant-squared beam, and iso-flux beam is performed using Taylor window-weighted AEPs, and the results are compared with those of beam shapes using ideal isotropic patterns. The results demonstrate that various beam shapes can be achieved for high-power electronic warfare applications using the AEPs of an actual array antenna. [ABSTRACT FROM AUTHOR]

In this paper, a new broadband microstrip slot antenna operated at millimeter wave (mm-wave) band and utilized in 5G systems is introduced. The suggested radiator composed of a rectangular slot etched on the ground plane with internal embedded L-shaped stub inside it. Parametric studies were done on three major dimensions of the proposed antenna to study the effect of these parameters on the bandwidth. The proposed radiator operates from 23.78 GHz to 50 GHz with impedance bandwidth of 26.22 GHz. Therefore, the proposed antenna supports the new 5G millimeter wave bands that cover (24.25 - 29.5) GHz, (37 - 43.5) GHz, (45.5 - 47) GHz, and (47.2 - 48.2) GHz bands. The gain of the proposed slot antenna element varies from 4.3 dBi to 8 dBi with average value of 5.5 dBi. A novel 6×6 multiple-input multiple-output (MIMO) structure is introduced. The proposed MIMO radiator was fabricated on Roger4003C substrate. The isolation between each two adjacent antennas is below -35dB over the required 5G mm-Wave spectrum. The value of the envelope correlation coefficient between the antenna elements does not exceed 0.011. The diversity gains (DG) between the radiators exceeds 9.94 dB. There is a good agreement between the simulated and the measured results. [ABSTRACT FROM AUTHOR]

The object of the study is a compact heptagonal broadband antenna specially designed for use in the 5G millimeter band using Koch fractals to improve performance. As a result of the study, the most important problem of achieving higher gain, improving bandwidth and reducing interference at higher frequencies, which is necessary for the effective functioning of 5G networks, was solved. As a result, the maximum realized gain of 5 dB was obtained at a frequency of 27.58 GHz with an impressive bandwidth in the range from 26.5 to 40 GHz. The use of Koch fractal geometry and defective ground planes significantly improves impedance matching and expands bandwidth, which explains the excellent antenna performance compared to traditional designs. The features and distinguishing features of the results obtained, thanks to which they allowed solving the problem under study, are its compact dimensions (only 9 mm by 9 mm) and the ability to maintain VSWR at a level of less than 2 in the entire frequency spectrum. These features make the antenna particularly suitable for millimeterband integration and flexible applications such as portable devices and wearable home appliances. The field of practical application of the results includes integration into portable and wearable devices, improving the performance and connectivity of Internet of Things applications. The conditions of practical use require compliance with 5G network standards and compatibility with millimeter-wave technologies. This characterizes the antenna as a significant achievement in antenna technology, demonstrating its potential for widespread adoption in next-generation wireless communication systems and paving the way for more reliable and highperformance wireless networks. [ABSTRACT FROM AUTHOR]

A compact and broadband dual-mode dipole antenna is proposed in this paper. Fundamental mode (f1) is combined with third-order mode (f3) to widen the bandwidth. To do so, f3 is compressed/down-shifted close to f1. This is realized by loading a loop at the current null points of f3. Loop parameters are the crucial parameters for third-order mode compression and, thus, for wide bandwidth. The antenna was fabricated. Measurements were performed. Simulations and measurements are in good agreement. The prototype of the antenna has an electrical size of 0.33λL× 0.08λL at the lowest frequency of the operational band. The obtained frequency band for |S11| ≤ −10 dB is 2.83 GHz–6.08 GHz which amounts to 73% bandwidth. The measured peak gain is 3.1 dBi. Stable omnidirectional radiation is obtained over the entire impedance bandwidth. [ABSTRACT FROM AUTHOR]

Ever‐increasing bandwidth requirements from various industries drive the need for the ever‐increasing bandwidth of antennas used for testing. Broadband Double‐Ridged Guide Horn (DRGH) antennas are used extensively in antenna measurement and ElectroMagnetic Compatibility/Interference (EMC/I) testing. The current state‐of‐the‐art broadband DRGH antennas reported in the literature for use in measurement applications cover bandwidth ratios as large as 36:1 (0.5–18 GHz). This paper presents the design and realisation of a DRGH antenna with a 100:1 bandwidth ratio (0.5–50 GHz). To achieve such a wide bandwidth, the ridge gap, width and feed were optimised, and a novel coaxial‐to‐ridge waveguide launcher section based on a typical Vivaldi antenna was developed. Backward radiation was reduced using an absorber‐filled cavity. A prototype DRGH antenna was manufactured using additive manufacturing, also referred to as 3D printing. Simulated and measured results obtained in an anechoic chamber are presented. [ABSTRACT FROM AUTHOR]

Among the existing circularly polarized multibeam transmitarray antennas, circularly or linearly-tocircularly polarized transmitarray units are always required. Naturally, designing circularly polarized units is more challenging than linear polarization. To simplify design and increase operation bandwidth, a novel method using linearly polarized transmitarray units and feeding sources is proposed for designing the circularly polarized multi-beam antenna. Broadband circular polarization is realized by utilizing sequential rotation technology and 1-bit phase compensation of linearly polarized transmitarray units. Meanwhile, beam scanning is achieved by using linearly polarized feeding sources offset. To validate the design, two multi-beam antenna samples are demonstrated. Simulated and measured results show that the designed multi-beam transmitarray antennas can realize beam scanning to 0°, ±10°, and ±20° in E-plane and H-plane. Moreover, two antennas maintain –10-dB impedance bandwidth and 3-dB axial ratio (AR) bandwidth at 8.5–10.4 GHz and 8.5–10.5 GHz, respectively. The proposed circularly polarized multi-beam transmitarray antennas have the advantages of broadband operation, simple design, and low cost. [ABSTRACT FROM AUTHOR]

A one-dimensional active broadband phased array based on microwave photonics that works in the Ku band is proposed to achieve a large instantaneous bandwidth. The phased array uses a feeding network based on microwave photonics to provide the true time delay and a wide operating bandwidth. The array is mainly composed of a broadband horn antenna, an RF transmitting/receiving module, an optical network module, and a temperature control module. The form of a horn was selected for the antenna unit, and it was fed through a waveguide to obtain a wide operating bandwidth. An optical fiber delay line that could realize the true time delay at different frequencies was adopted for the time-delay module of the optical network. To obtain a large time delay and small quantization error, a hybrid time-delay diagram utilizing electrical and optical time delays was used in the design. In addition, a temperature control module was added to the antenna system to enhance the stability of the photonic time-delay module. For verification, a prototype of the presented antenna system was designed, fabricated, and measured. The experimental results showed that the optical phased array antenna was able to scan ±20° from 12 GHz to 17 GHz, and the beam pointing did not appear to be offset over the wide operating bandwidth. [ABSTRACT FROM AUTHOR]

Shared-radiator design of a broadband and dual-mode antenna that simultaneously covers the VHF/UHF band and satellite navigation band is presented for personal role radio (PRR) applications. Quadrifilar helix antenna (QHA) is devised to be a circularly polarized radiator which as well acts as a part of the upper half radiation arm of the dipole antenna and be equivalent to a linearly polarized radiation current carrier at VHF/UHF band, forming a symmetrical dipole antenna with a sinusoidal current distribution. A 5th-order balanced matching network comprised of five cascade L-sections is adopted to obtain the maximum possible working band-width and a 3.76:1 band-width (116 %) at VHF/UHF band is achieved. Strong mutual coupling effect of the two operating modes is observed near 1.5 GHz originated from QHA shared-radiator design, and a new balun structure is applied to achieve high isolation and self-decoupling, subsequently |S21| of the two operating modes is significantly reduced from about −18 dB to below −32 dB at satellite navigation band without affecting the reflection coefficient and radiation efficiency. The measured results show that radiation patterns of the manufactured prototype is basically consistent with corresponding simulation counterparts. [ABSTRACT FROM AUTHOR]

This article presents a novel compact design of an annular ring microstrip antenna (ARMSA), which has two stacked annular rings and is fabricated on a FR4 substrate for radar and satellite applications. The presence of different kinds of slots made the design of the recommended antenna very unique for Ku band applications. This novel compact structure of the antenna provided enhanced bandwidth and high gain. The suggested antenna works in Ku band and has 2.70 GHz bandwidth and 8.42 dB gain, which makes it suitable for satellite applications. The quality parameters of the proposed annular ring microstrip antenna have been compared with other existing annular ring microstrip antennas, which shows its efficient performance. [ABSTRACT FROM AUTHOR]

A compact Ka-band antenna array has been proposed to realize broadband and high gain for millimeter-wave applications. The antenna array is divided into a multilayer composed of a driven slot patch layer and a parasitic patch array layer, which is excited by a mixed CPW-Slot-Couple feeding network layer. According to characteristic mode analysis, a pair of narrow coupling slots are introduced in the driven patch to move the resonant frequency of characteristic mode 3 to the resonant frequency of characteristic mode 2 for enhanced bandwidth. In this article, a 1to4 CPW-Slot-Couple feeding network for a 2 × 2 driven slot patch array is implemented, and then each driven slot patch excites a 2 × 2 parasitic patch array. Finally, a proposed 4 × 4 × 3 (row × column × layer) Ka-band antenna array is fabricated to verify the design concepts. The measured results show that the frequency bandwidth of the antenna array is 25 GHz to 32 GHz, and the relative bandwidth is 24.5%. The peak gain is 20.1 dBi. Due to its attractive properties of miniaturization, broadband, and high gain, the proposed antenna array could be applied to millimeter-wave wireless communication systems. [ABSTRACT FROM AUTHOR]