Broadside Gain Research Articles

Wideband filtering antenna design inspired by synthesis of flat‐top broadside gain curve

AbstractA common design solution of wideband filtering antennas inspired by the synthesis of a flat‐top gain curve is proposed by using mutual coupling effects. The realization of a frequency‐varied flat‐top gain curve based on specially designed subarrays is analyzed. Analysis results conclude a design process of generating filtering response based on shorting pins and parasitic structures. A single‐layer rectangle patch array loaded with parasitic shorted patches is designed and analyzed for the validation. The proposed antenna possesses an impedance bandwidth of 4.95–6.05 GHz and a peak realized gain of 11.2 dBi. Besides, the design has its out‐of‐band rejection levels higher than 15 dB.

A Broadband MS-Based Circularly Polarized Antenna Array Using Sequential-Phase Feeding Network.

This paper introduces the design of a circularly polarized metasurface-based antenna array for C-band satellite applications that owns broadband operation and high gain characteristics. The single radiating element comprises a Y-shape patch and an above-placed 2 × 2 unit-cell metasurface. Further improvement in operating bandwidth and broadside gain is achieved by arranging four single elements in a 2 × 2 configuration and a sequential-phase feed network. A prototype has been fabricated and measured to validate the feasibility of the proposed antenna array. The measured operating bandwidth is 20% (4.50-5.50 GHz), which is an overlap between a -10 dB impedance bandwidth of 29.8% (4.50-5.99 GHz) and a 3 dB axial ratio bandwidth of 20% (4.50-5.50 GHz). Across this operating band, the peak broadside gain is 10.5 dBi. Compared with the recently published studies, the proposed array is a prominent design for producing a wide operating bandwidth and relatively high gains while maintaining the overall compact dimensions.

Frequency-Reconfigurable Millimeter-Wave Rectangular Dielectric Resonator Antenna.

This paper introduces an innovative and cost-effective approach for developing a millimeter-wave (mmWave) frequency-reconfigurable dielectric resonator antenna (DRA), which has not been reported before. The antenna integrates two rectangular DRA elements, where each DRA is centrally fed via a slot. A strategically positioned PIN diode is employed to exert control over performance by modulating the ON-OFF states of the diode, thereby simplifying the design process and reducing losses. In the OFF state, the first DRA, RDRA-I, exclusively supports the TE311 resonance mode at 24.3 GHz, offering a 2.66% impedance bandwidth and achieving a maximum broadside gain of 9.2 dBi. Conversely, in the ON state, RDRA-I and RDRA-II concurrently operate in the TE513 resonance mode at 29.3 GHz, providing a 2.7% impedance bandwidth and yielding a high gain of up to 11.8 dBi. Experimental results substantiate that the proposed antenna presents an attractive solution for applications necessitating frequency-reconfigurable and high-performance mmWave antennas in 5G and Beyond 5G (B5G) communication systems.

Compact and Highly Isolated Continuous Scanning Dual-Polarized Holographic Antenna Using a Pillbox Feeding Structure

In this paper, we propose a novel approach to realize a compact and highly isolated dual-polarized holographic antenna using a pillbox feeding structure. The proposed antenna feeds dual orthogonal surface waves with low distortion phase distribution and high isolation through a compact three-layer pillbox feeding structure. This antenna also consists of a shared aperture dual-polarized hologram pattern calculated to radiate the objective wave in the desired direction without increasing the antenna size. As a result, the proposed holographic antennas (HA) have a compact size and support forward-to-backward continuous scanning with minimal gain degradation. The simulated and measured results are in good agreement, validating the efficiency of the proposed antenna design, which has the ability to scan the beam direction from +18° to −25°, passing through the broadside within the frequency range of 21–27 GHz. Finally, the proposed antenna has a broadside gain of 18.5 dBi in each polarization and a gain variation of less than 2 dB within the operating bandwidth.

On-Chip Circularly Polarized Circular Loop Antennas Utilizing 4H-SiC and GaAs Substrates in the Q/V Band.

This paper presents a comprehensive assessment of the performance of on-chip circularly polarized (CP) circular loop antennas that have been designed and fabricated to operate in the Q/V frequency band. The proposed antenna design incorporates two concentric loops, with the outer loop as the active element and the inner loop enhancing the CP bandwidth. The study utilizes gallium arsenide (GaAs) and silicon carbide (4H-SiC) semiconductor wafer substrates. The measured results highlight the successful achievement of impedance matching at 40 GHz and 44 GHz for the 4H-SiC and GaAs substrates, respectively. Furthermore, both cases yield an axial ratio (AR) of less than 3 dB, with variations in bandwidths and frequency bands contingent upon the dielectric constant of the respective substrate material. Moreover, the outcomes confirm that utilizing 4H-SiC substrates results in a significantly higher radiation efficiency of 95%, owing to lower substrate losses. In pursuit of these findings, a 4-element circularly polarized loop array antenna has been fabricated for operation at 40 GHz, employing a 4H-SiC wafer as a low-loss substrate. The results underscore the antenna's remarkable performance, exemplified by a broadside gain of approximately 9.7 dBic and a total efficiency of circa 92%. A close agreement has been achieved between simulated and measured results.

Circularly polarized gap-coupled variations of square microstrip antennas employing U-slot for WLAN and bluetooth applications

ABSTRACT Circularly polarized gap-coupled variations of square microstrip antennas using U-slot are proposed in 2400 MHz frequency spectrum for WLAN and Bluetooth applications. Design with patches gap-coupled along the two coordinate axes provides the optimum results. It yields axial ratio bandwidth of 376 MHz (15.8%) with a maximum broadside gain of above 10 dBi. Design methodology based on the resonant length formulation is proposed that helps in designing similar antennas in other frequency bands. Measurements have been carried out to validate the simulated results that show close agreement.

Broadside Gain Enhancement of Wideband Monopole Circular Shaped Antenna Using FSS for Sub-6 GHz Applications

This paper introduces a wideband circular patch antenna designed with a frequency selective surface (FSS) for sub-6 GHz applications. The proposed antenna features a monopole circular-shaped patch with a partial ground plane, delivering an omnidirectional radiation pattern in the azimuth plane, resulting in relatively uniform gain in all directions. An FSS metamaterial enhances the antenna's gain and improves the broadside radiation pattern. The design incorporates three inner circular patches connected to the main patch. The FSS utilizes hybrid square/circle loop-based unit cells. The antenna and FSS are simulated using CST software and subsequently fabricated on an FR-4 substrate. The measured results demonstrate an impedance bandwidth of 1.6 GHz with a peak gain of 5.4 dB at 3.5 GHz. The omnidirectional radiation pattern is converted into a directional one by placing a reflector FSS as a bottom substrate layer. The overall structure size is compact, measuring (0.34λ0 × 0.27λ0 × 0.016λ0), where λ0 is the free space wavelength corresponding to the lowest resonant frequency within the operational bandwidth. This design achieves significant antenna size reduction and is well-suited for future sub-6 GHz applications.

A conformal multi-port MIMO patch antenna for 5G wireless devices

This paper presents a multiple-input-multiple-output (MIMO) antenna array with low-profile and flexible characteristics. Multiple microstrip patches are arranged in the E-plane configuration and decoupled by shorted quarter-wavelength stubs. The antenna has a small element spacing of 0.032 λ, where λ is a free-space wavelength at the center frequency. To demonstrate the feasibility of the proposed concept, a 1 × 4 MIMO array prototype is fabricated. The measured results on the fabricated prototype demonstrate that the MIMO antenna has good operation features at 4.8 GHz with a reflection coefficient of less than –10 dB and an isolation of better than 20 dB. Besides, good radiation patterns and broadside gain of around 4.5 dBi are also attained. The antenna also works in the bending mode and has the capability of extending to large-scale MIMO arrays. Such attractive features prove the utility of the proposed antenna in various modern electronic devices.

A low profile perturbed CDRA with convex conformal ground plane excited by differential feed

A low profile, Convex Conformal Cylindrical Dielectric Resonator Antenna (CCCDRA) with perturbation excited by dual coaxial probes in Differential Feed Arrangement (DFA) with TM11δ and TM21δ modes being observed at 7.7 GHz, and 8.7 GHz respectively, is presented and examined in this paper. The radiation performance of the bent Cylindrical Dielectric Resonator Antenna (CDRA) is investigated and it can be observed that at the bent angle of φ1 = 24°, high broadside gain is obtained therefore it is chosen for the proposed design. Investigation on the DFA is carried out and it is observed that the differentially driven CDRA offers a low cross polarization as well as directional broadside radiation pattern. Wide impedance bandwidth is achieved by perturbing the CDRA in such a way so as to maximize the Surface Area to Volume (S/V) ratio, resulting in lowering the Q-factor. A high-gain of 9.6 dBi at 8 GHz for wideband wireless applications, featuring 30.5 % fractional bandwidth is achieved. Additionally, the proposed CDRA has a height of 0.16 λ0 with a low profile. The simulation results are found to be in good agreement with the experimental measurements performed on a fabricated prototype.

Wideband Millimeter-Wave MIMO Antenna with a Loaded Dielectric Cover for High-Gain Broadside Radiation

In a millimeter-wave terminal device, the use of a radome degrades the radiating performance of the broadside antenna, especially for the MIMO antenna system. In this study, a dielectric cover is de-signed and investigated to enhance the broadside gain of a millimeter-wave MIMO antenna, while keeping its wideband and high isolation performance. Firstly, a compact wideband ladder-shaped slot antenna is proposed with 21.9% bandwidth. The effectiveness of the dielectric cover design criteria over the wideband antenna is investigated. Then, this wideband antenna element is expanded to a 2 × 2 MIMO antenna by forming a center-symmetric structure and isolating it via the inserted metal vias. By loading the dielectric cover, this millimeter-wave MIMO antenna is verified with enhanced broadside gain for more than 2.1 dB. With the measured impedance bandwidth of 21.9% (57.0–71.0 GHz), peak broadside gain of 12.3 dBi, and high isolation over 15 dB, the proposed MIMO antenna is suitable for wireless gigabit terminal devices.

Microstrip Leaky-Wave Antenna With Circular Polarization and Broadside Radiation

In this letter, a novel circularly polarized microstrip leaky-wave antenna is proposed with broadside radiation and high gain. A conventional microstrip patch has been modified to obtain broadside gain along with circular polarization. The modified patch is periodically placed along one side of the 50 Ω delay line to form leaky-wave antenna. The optimized broadside frequency of the antenna is 10.1 GHz. The bandwidth associated with 3-dB axial ratio is 13.3% while the maximum obtained gain is 15.8 dBic. The measured gain variation within 3-dB axial ratio bandwidth is 1.6 dB. Measured results of the fabricated antenna follow the simulations.

A compact metasurface-based circularly polarized antenna with high gain and high front-to-back ratio for RFID readers.

Developing a compact circularly polarized (CP) antenna with good radiation characteristics for handheld radio frequency identification (RFID) readers is a very challenging task. Many compact CP antennas have been reported in the open literature, but most suffer from critical drawbacks of low gain and/or high back radiation. This paper presents a metasurface (MS) based CP antenna with compact size, high gain, and high front-to-back ratio characteristics. The compact size of the proposed design is achieved by using a 2 × 2 unit-cell MS, while the CP realization is accomplished through a coupling between the MS and a Y-shaped patch as a primary CP source. The final antenna has compact overall dimensions of 0.45λ × 0.45λ × 0.02λ, where λ is the guided wavelength at the center frequency. The operating bandwidth is about 2.0% (2.43-2.48 GHz) and the broadside gain is about 6.3 dBi. Besides, the front-to-back ratio (FBR) defined by the difference gain levels between the forward and backward directions is about 18 dB. Compared with the related compact CP antennas in the literature, the proposed design has the advantages of high gain and high FBR, making it suitable for compact RFID readers.

Design of folded rectangular microstrip antenna on thinner substrate for wideband response

ABSTRACT Wideband microstrip antenna is realized by adding more than one resonant modes in the patch. In this paper, on electrically thinner substrate, design of modified shape rectangular microstrip antenna by employing folded rectangular patch is presented for linear polarized wideband response. Unlike the conventional rectangular patch, radiation pattern and resonance frequency at the second-order resonant mode are modified and along with the fundamental mode, yield wider bandwidth. On substrate of thickness 0.045λ0, folded patch design yields bandwidth of more than 20% along with the broadside radiation pattern and gain more than 8 dBi. Against the reported wideband designs, proposed design does not employ parasitic patches, resonant slot, modified ground plane structures, but on thinner substrate achieves the bandwidth of more than 20%. Resonant length formulation and subsequent design methodology are presented, which is useful in realizing similar folded antenna as per the specific frequency band. Simulated results have been experimentally verified, which shows close agreement.

Gain and Frequency-Selectivity Enhancement of Dual- Polarized Filtering IBFD Antenna Using PRS

A dual-polarized filtering Fabry–Perot antenna (FPA) with high selectivity and high isolation is proposed for in-band full-duplex (IBFD) applications. The proposed antenna utilizes a square patch as the feeding element, which is fed by a double differential-fed scheme for dual-polarized radiation with high isolation. The patch is loaded with a symmetrical cross-slot and four shorting pins for a broad passband filtering feature. To enhance broadside gain across a wide frequency range, the patch is incorporated with a partially reflecting surface (PRS), which is composed of two complementary cross-slot and patch arrays. Moreover, the frequency selectivity of PRS is exploited to improve the filtering characteristic. The double differential feeds are realized based on out-of-phase power dividers, which are combined with simple low-pass filters to further improve the out-of-band suppression. The final design was fabricated and measured. The measurement results show excellent results with a 10-dB return loss bandwidth of 21.5% (4.91–6.09 GHz), isolation of greater than 40 dB, peak gain of 13.7 dBi, out-of-band suppression level of better than 27 dB, and a cross-polarization level of less than –27 dB.

Broadband and high gain coupled and cascaded square ring antenna for RADAR applications

Gain and bandwidth are the two primary performance characteristics of an antenna that dictate its role and utilization. In this paper, the design and fabrication details of a coupled and cascaded square ring antenna for S-band (2–4 GHz) radar communications such as navigation applications are presented. The design is employed by two square coupled rings for bandwidth enhancement and two in-phase cascaded square rings for enrichment in gain. The fabricated antenna has delivered 33% (2.52–3.52 GHz) of 10-dB bandwidth and 11.2–13.1 dBi of broadside gain. The in-phase cascading ring technique improved the antenna's gain without increasing reflector size and ring height. Thus, the proposed design is compact, with a height of 0.2λ and a total planar area of 2λ2. Moreover, the performance of the antenna is presented for variations in the geometrical parameters also.

Advanced Design of High-Gain Fabry–Perot Cavity Antenna Offering Wide Common Impedance and Gain Bandwidth

An advanced design of a Fabry-Perot cavity antenna (FPCA) is proposed to achieve wide common impedance and gain bandwidth along with high gain. A compact and lightweight FPCA is achieved by employing a printed primary radiator and superstrate with superior manufacturing capabilities. A wideband primary radiator is employed for the first time to realize such a wideband FPCA. Superstrate dimensions are estimated by using the aperture field theory and the proposed design is validated through both EM simulation and experiment. The measured broadside gain is shown to be better than 11.5 dBi over an impedance bandwidth of 63% (8.2−15.6 GHz). About 40% common impedance and gain bandwidth is achieved while the broadside gain attains a maximum value of 17.4 dBi. To the best of our knowledge, this has never been achieved before from an FPCA made of a printed superstrate and a primary radiator. The cross-polar (XP) radiation remains under −40dB whereas the front-to-back ratio (FBR) remains above 35dB, over the desired bandwidth.

Design and Optimization of a High-Gain Filtering Antenna Based on Parasitic Pixel Layer

A novel high-gain filtering antenna based on the parasitic pixel layer is designed and optimized in this paper. Initially, a circular patch surrounded by a shorted concentric annular ring one is proposed as the radiation source, such a design is able to realize an upper radiation null. Afterward, a parasitic pixel layer is placed upon the radiation source with an air gap. Another radiation null at the lower band is then obtained by optimizing the connection status between adjacent pixel elements based on the internal multi-port method. Besides that, the parasitic pixel layer can enhance the realized broadside gain. Finally, a high-gain filtering antenna with a bandpass response is obtained. The antenna is validated by a full-wave simulation study followed by the experimental verification. Measured results indicate that the antenna can operate from 4.7 to 5.4 GHz with an average gain of 9.6 dBi and two radiation nulls at the lower and upper band edges of the reflection coefficient curve.

Millimeter-Wave 1-D Wide-Angle Scanning Pseudo-Curved Surface Conformal Phased Array Antennas Based on Elongated Planar Aperture Element

To perform wide-angle scanning while maintaining a planar low profile, we propose a new kind of millimeter-wave (mmWave) planar phased array antenna using inclined beam elements to imitate a curved surface conformal (CSC) array, called a pseudo-curved surface conformal (PCSC) phased array antenna. We present the concept of our PCSC phased array and then design an elongated planar aperture antenna (EPAA) element, achieving stable high broadside gain and wide beam on the scanning plane within a wide bandwidth. Then, by introducing asymmetries to the EPAA element, the beam inclination of the EPAA element can be adjusted. Accordingly, we use EPAA elements with different beam inclinations to form a 1 × 4-element 1-D wide-angle scanning PCSC phased array antenna. We design, fabricate, and measure a prototype of our proposal, with measured results showing that the proposed design has a 3 dB gain variation across a scanning range of more than ±62° (and as high as ±68°) within the 5G mmWave band (24.25 to 29.5 GHz), which is about ±10° better than its traditional counterpart.

Beam‐squint rectified balanced antipodal Vivaldi antenna with sliced fins and quarter‐wavelength labyrinth director

AbstractThis paper introduces a gain‐enhanced, beam‐squint rectified balanced antipodal Vivaldi antenna (BAVA) with symmetrically sliced fins and a novel square‐shaped metallic labyrinth director. The proposed antenna operates from 2 to 18 GHz with S11 less than −10 dB maintaining a fractional bandwidth of 160%, realizes 12.564 dBi as maximum gain at 18 GHz, and achieves greater than 3.415 dBi gain throughout the functioning band of frequency. Improvement of broadside gain by reconfiguration of current loops through symmetric slicing of radiating flares and beam‐squint correction using quarter‐wavelength labyrinth director are addressed by the proposed antenna. The maximum realized size of the antenna is 80 × 40 × 0.508 mm3. Consistent radiation patterns are observed at selected frequencies. Numerical evaluation with a full wave simulation tool and consequent experimental validation with a compact antenna test range is performed.

A novel dual-polarized gain-enhanced microstrip patch antenna

ABSTRACT A broadside direction gain-enhanced low-cost dual-polarized microstrip patch antenna has been presented. The proposed antenna consists of a slot-loaded cross-shaped patch and shorting pins. The orthogonal polarized radiating elements works in TM05 and TM12, meanwhile slot-loaded excite TM01. The equivalent magnetic currents (EMCs) amplitude, frequency, and flow direction of the TM12 are controlled by shorting pins to form the broadside gain enhancement. The superposition of them can enhance the gain in the broadside direction. The proposed antenna is coaxial feed. The substrate is divided into two layers: air and FR4. A copper column is added to the air layer to greatly improve the polarized isolation of the antenna. The size of the proposed antenna is 2.29λ 0×2.29λ 0×0.069λ 0 (λ 0 is the wavelength of free space at the central frequency). The simulated maximum realized gain is 12.59 dB, and the realized gain is better than 11.53 dB in operating band. The measured maximum realized gain is 12.05 dB, and the realized gain is better than 10.04 dB. The dual-polarized microstrip patch antenna has the advantages of low cost and high gain, which can be used in the modern wireless communication system.