Broadside Radiation Research Articles

A wideband and multibeam pattern reconfigurable antenna using partially reflecting surface

Abstract This paper presents a pattern reconfigurable antenna that accomplishes wideband and multibeam characteristics. The antenna design comprises a cross-slot radiator as the primary element and reconfigurable partially reflecting surface (PRS) layer placed above and below the cross-slot radiator. This configuration allows the antenna to adapt its radiation patterns effectively. The choice of the cross-slot radiator is based on its capability to offer wideband characteristics. The PRS layer consists of a precisely arranged array of 4×4 unit cells, incorporating PIN diodes into both the upper and lower PRS layers. The direction of radiation pattern can be changed by altering operating states of the PIN diodes on the PRS layer. The antenna operates in three distinct states, each exhibiting a unique radiation pattern. The antenna produces broadside, backward, and bidirectional radiation patterns. It demonstrates effective pattern reconfigurability across the frequency range of 3.10–3.86 GHz (21.71%), with a peak gain of 9.60 dBi. The simulated and measured results of the antenna are found to be in good agreement.

Normal‐mode planar meander‐line antenna array with bidirectional broadside radiation pattern

AbstractIn this letter, a normal‐mode planar bidirectional broadside antenna array with the merits of high gain, broadband, low aerodynamic drag, and high assembly robustness is proposed. First, the bidirectional antenna array is implemented based on a novel design strategy. The expected radiation field generated by currents along the same direction is superimposed while the unexpected radiation field is offset due to the out‐of‐phase currents, achieving a normal‐mode high‐gain bidirectional pattern. Then, the bidirectional antenna array is designed with two metallic meander lines, featuring low aerodynamic drag and cost‐efficiency. Moreover, a simple feed structure using an impedance transformer parallel strip line is adopted for a wide bandwidth. Besides, the bidirectional antenna array exhibits a stable impedance when the array scale increases. The stable impedance is also observed when the antenna array is bent to different angles, ensuring ease of installation and high assembly robustness. To validate the design strategy, a prototype with an aperture length of 5.8λ at 2.4 GHz is fabricated. The proposed antenna array is designed to operate from 2.2 to 2.6 GHz, with a maximum gain of 13 dBi around the center of frequency, which can be a promising candidate in long and narrow communication scenarios.

Enhanced breast tumor localization with DRA antenna backscattering and GPR algorithm in microwave imaging

With the rapid rate of increasing breast cancer cases across the globe and restrictions of existing early stage detection techniques, microwave imaging based cancer and malignant cell diagnosing methodology is finding its way. Microwave imaging technology has higher accuracy of detection in the variation of tissue properties. In this article, a dielectric resonator based wide band antenna is designed and investigated for microwave imaging (MWI) of early breast cancer detection due to its improved accuracy. The designed antenna has compact size, broad frequency spectrum, high gain and broadside radiation characteristics. To attain the wider bandwidth from (6.5 GHz–12.5 GHz), two rectangular shaped dielectric slabs are used. Wide band microwave frequency band supports the high resolution images. A C-shaped defected ground structure is used to tune the impedance matching. Dielectric resonator based antenna has higher gain and reduces the squints in antenna impedance. Two-asymmetrical dielectric slabs contribute in the excitation of different resonating modes which in turn enhance the bandwidth. It also contributes to excite multiple resonance mode that in turn enhance the bandwidth. Antenna performance is first numerically and experimentally verified in free space. Then, simulation based performance is examined for the microwave imaging. Numerical phantom with equivalent tissue properties is designed with and without the tumor. Unhealthy cells have higher water percentage and larger dielectric constant as compared to healthy cells. It causes the different in the back scattered signal of antenna, which is analyzed to diagnose the tumor or cancer. Here, a maximum deviation of 16 dB is observed in the backscattered signal. Furthermore, surface of the breast tissue is scanned along the x-axis and y-axis at different angels. The collected signals are used to reconstruct the microwave image of the interior. Mean value data of backscattered signals is used to locate the existence of unhealthy cells and GPR algorithm is used to calculate the depth of a 4 mm tumor in breast tissue. Proposed structure has shown efficient performance for microwave imaging.

An in‐band full‐duplex antenna for 2.4 GHz WLAN using differential‐feed based neutral coupling for isolation enhancement

AbstractThis article introduces a unique design approach for a compact in‐band full‐duplex (IBFD) antenna with good isolation in a wider bandwidth at the 2.4 GHz WLAN. The meander slot baluns are innovatively constructed in the feeding network, one balun on the top substrate layer and the other on the bottom substrate layer of the ground, to realize double differential feeding and polarization diversity. The metallic vias that connect one of the baluns in the feeding network with the co‐radiating patch further reduce the antenna's overall size. The balun's neutral coupling characteristics of differential potentials, which reduce the leakage currents by creating null potential, and differential filtering, which suppresses the leakage currents by non‐coupling fields, generate high isolation in the antenna. The designed balun offers a stable differential feed with a trivial magnitude and phase imbalances of (0.04–0.06) dB and , respectively. The antenna offers a minimum isolation of 78 dB with a wider bandwidth of 130 MHz. The far‐field measurement shows broadside radiation with low cross‐polar levels of less than −32 dB. A prototype is fabricated on FR‐4 substrate layers with an overall size of (0.8 × 0.8 × 0.012) ( is the free space wavelength of the frequency GHz) to validate the proposed design performance. The measured results of the prototype properly correlate with the simulated results.

Design of Broadband Phased Array Feed Using Stereolithographic Additive Manufacturing Heterogeneous Integrating Technology for Fast Radio Burst Observation

Herein, a stereolithography appearance 3‐D printed phased array feed (PAF) on radio telescopes based on broadband Vivaldi antenna elements covering 4–10 GHz, which meets the requirements of low cost, lightweight, and compact volume, is designed and proposed. The prototype is integrated with two orthogonal linear polarized 4 × 5 arrays, each of which is composed of 20 Vivaldi antenna elements. The distance between adjacent antenna elements is 1/2 λ in both E‐plane and H‐plane. By increasing thickness of the slice elements compared with traditional end‐fire arrays on printed circuit board, the wide‐band impedance matching is realized. The mutual impedance matrix of the dual‐polarization array is calculated and the equivalent circuit of the active and parasitic elements is demonstrated. Due to the orthogonal parasitic elements inserted between the adjacent active antennas, equivalent capacitance is introduced in the tightly coupled array. The measured active voltage standing wave ratio of the manufactured PAF exhibits 4–10 GHz operating bandwidth for both broadside radiation and 45° scan in both E‐ and H‐plane polarization. The proposed wideband PAF has a promising potential application prospect in fast radio burst and other astronomic observation.

A wide angle beam scanning CRLH leaky-wave antenna with non-identical elements per unit-cells

In this research article, a wide-angle scanning leaky-wave antenna (LWA) based on the composite right/left-handed (CRLH) metamaterial (MTM) operating over the C-band spectrum for mobile applications is proposed, investigated, and realized. The proposed LWA includes nine CRLH-MTM-based unit-cells. The properties of CRLH-MTM have been applied using series slots and shunt metallic via-holes. Each unit cell consists of three patches, two external patches, and one smaller middle patch implemented between them. One slot has been etched on each external patch; the width of these two slots is unequal. Moreover, the distance of the middle patch with each side patch is different. The results show that using this method of realizing non-identical elements caused the achievement of proper return-loss at the transition frequency and provided the balanced CRLH metamaterial condition. Additionally, using CRLH-MTM properties by realizing series capacitance (slot) and shunt inductance (via-holes) made the wide-angle scant from backward to forward radiation pattern. The results demonstrate that the LW antenna with small dimensions of 251.5 × 30 × 1.575 mm3 operates over a frequency range of 4.8–6.13 GHz covering a wide beam scanning range from −63° to +65° with broadside radiation at the center frequency of 5.46 GHz. The radiation gain of the proposed antenna varies from 6.2–13.1 dB. The achievements confirm the effectiveness of the proposed methods to realize a high-performance LW-antenna with the advantages of simple design, low profile, low cost, and easy of manufacture for mobile applications.

A low‐profile four‐degrees of freedom antenna by collocating a ±45°‐polarized dipole and a dual‐polarized microstrip antenna with broadside radiations

AbstractThis letter proposes a novel four‐degrees of freedom (4‐DOFs) antenna for 5.8 GHz wireless local area network band communications. The proposed antenna realizes 4‐DOFs with a low profile (0.11λ), which is composed of ±45°‐polarized dipole (DP), an artificial magnetic conductor (AMC) reflector, and a dual‐polarized slot‐loaded microstrip antenna (MA). The whole size of the proposed antenna is 83 mm × 83 mm × 5.9 mm (1.6λ × 1.6λ × 0.11λ). The DP is printed on the substrate with the wideband characteristic, and the MA operates at TM50 mode. The AMC reflector operating for the DP is designed for the low profile, causing the low isolations between the DP and the MA. The broadside radiation with 4‐DOFs is first reported. The envelope correlation coefficients are lower than 0.07, and the DOFs are 3.75. The measured results are in accord with the simulated results.

A planar-structured circularly polarized single-layer MIMO antenna for wideband millimetre-wave applications

This paper presents a planar multiple-input-multiple-output (MIMO) antenna with dual circular polarization (CP) and a simple geometry for millimetre-wave band. The proposed design is featuring a fully grounded coplanar waveguide (CPW) and a systematically perturbed feedline radiator. The symmetry of the electric field is disrupted using varying stub sizes and offsets between the stubs, resulting in wideband operation and circularly polarized waves. Following full optimization of the physical parameters, the numerical design is validate experimentally. The results indicate that the proposed antenna design achieves a −10 dB impedance bandwidth from 24.6 GHz to 32.1 GHz, with an axial ratio (AR) of 3 dB or less from 26 GHz to 31.8 GHz. The peak realized gain is 10.3 dBic, with steady broadside radiation. The envelope correlation coefficient (ECC) is 0.01, and the diversity gain is 10 dB across the operating band. The planar structure and the wideband performance of the proposed design makes it suitable for application necessitating fix beam applications in the mm-wave band.

A low‐profile, wideband, circularly polarized, slotted, U‐shaped textile antenna for W‐BAN applications

AbstractWe propose a compact, wideband, U‐shaped, circularly polarized textile antenna (UCPTA) resonating at 2.45 GHz for wireless body area network (W‐BAN) applications. The radiator of the antenna is printed on the top of the substrate (size of mm3; ) and has a full ground plane on the other side. The proposed antenna's substrate consists of a single layer of denim (), and conductive copper tape was used to fabricate the patch. The antenna has a low‐profile design that is suitable for wearable applications. A small slot was introduced at the center of the U‐shaped patch to enhance the 3 dB axial ratio bandwidth (ARBW) up to 55.17%. The proposed antenna radiates with a 10 dB return loss (RL), impedance bandwidth (IBW) of 64.40%, and a simulated gain of 5.1 dBi. The wearable textile antenna with broadside radiation response is appropriate for off‐body communications. The prototype of UCPTA is fabricated for experimental validation. The measured results for the fabricated antenna were in good agreement with the simulated results. Further, it has been demonstrated that the antenna's performance is stable during structural deformation and human body loading. This textile antenna covers an ARBW in the frequency band of 2.1 GHz–3.72 GHz and has a broad IBW (2 GHz–3.9 GHz) for LTE (2.17 GHz), MBAN (2.360 GHz–2.4 GHz), WPAN (2.395 GHz–2.4 GHz), and WLAN (2.4 GHz–2.482 GHz) applications.

A substrate-integrated waveguide-based wideband circularly polarized slot antenna using the parasitic square patch array

In this paper, a planar low-profile wideband circularly polarized substrate-integrated waveguide (SIW) based antenna is investigated. The antenna comprises two substrates stacked over each other. The top layer of the antenna is loaded with a 4 × 4 array of parasitic square patches stacked over a spiral slot loaded in the SIW cavity. The spiral slot is utilized for the generation of narrow band circular polarization and to enhance the CP bandwidth, the parasitic patch array is excited through the electromagnetic coupling mechanism without any air gap between them. The antenna is fabricated and tested to validate the simulated results. A wide relative impedance bandwidth of 33% (8.25–11.55 GHz) and the axial ratio bandwidth of 8.55–9.70 GHz (12.60%) is exhibited. The broadside radiation characteristics are achieved with peak gain of 8.05dBic at 9 GHz. The overall size of the antenna structure is 0.8λ0 × 0.8λ0. The proposed antenna is suitable for various satellite applications.

Dual-Band Antenna with Pattern and Polarization Diversity.

This study proposes a pattern-diversity antenna with different radiation patterns at two different frequency bands (f1 and f2; f1: broadside radiation pattern, f2: conical radiation pattern). The proposed structure consists of a central circular antenna and two annular ring antennas, with each of the antennas having individual ports. Two of the ports (port 1 and port 3) exhibit orthogonal broadside radiation patterns at low bands, and the other two ports (port 1 and port 2) exhibit orthogonal conical radiation patterns at high bands. Thus, they have polarization diversity characteristics. To improve isolation between the ports, the inner part of the annular ring antennas is shorted by an array, and the outermost port is positioned orthogonal to the other ports. Using this configuration, the isolation values between the ports are -26.7 and -30.1 dB at the two frequency bands, respectively. Using the fabricated prototype, experimental results show that the proposed antenna achieves -10 dB bandwidths of 240 MHz (5.71-5.95 GHz) and 210 MHz (7.69-7.9 GHz) at f1 and f2, respectively.

A low-profile frequency- and pattern-reconfigurable metantenna for UAV joint RadCom systems

To address the specific requirements of antennas in Unmanned Aerial Vehicle (UAV) joint radar-communication (RadCom) systems, a novel low-profile reconfigurable metantenna with the capability of frequency and pattern reconfiguration is proposed in this paper. The proposed antenna consists of a metasurface layer with 3 × 3 square unit cells and a simple feeding network with two pairs of PIN diodes. Specifically, the designed metantenna has a low profile of 0.064 λ0 (λ0 is the free space wavelength at 5.5 GHz). And measured results show that, for the broadside radiation mode, the −10 dB operating bandwidth is about 12.1 %, ranging from 5.05 to 5.7 GHz with a maximum gain of 8.9 dBi. For the conical radiation mode, the −10 dB operating bandwidth is about 21.9 %, ranging from 5.88 to 7.33 GHz with a maximum gain of 6.83 dBi. Given its excellent radiation performance, the metantenna designed for UAV joint RadCom systems holds significant research significance and value in the field of multifunctional reconfigurable antennas.

A Radiation-Pattern Reconfigurable Antenna Array for Vehicular Communications.

This paper presents a low-profile reconfigurable antenna array capable of five radiation-pattern modes for vehicular communication applications. The antenna array consists of four antenna elements, each containing four square patches. Exciting one of the square patches generates a broadside radiation. A square parasitic patch is added at the rear of the excited patch, and two square parasitic patches are placed at the front. By optimizing the design of these parasitic patches, including the treatment of center slotting and addition of shorting pins, the antenna element achieves an end-fire beam with a certain tilt angle. On this basis, a reconfigurable feeding network is designed with 1:1 and 1:4 output modes. By connecting the reconfigurable feeding network to the four antenna elements and altering the on/off states of the PIN diodes in the feeding network, a reconfigurable antenna with four end-fire beams and one omnidirectional beam in its radiation pattern is realized. Measurement results demonstrate an excellent impedance bandwidth, radiation pattern, and gain performance in all modes. The four end-fire and one omnidirectional radiation characteristics make it highly suitable for vehicular communication applications.

Enhancing connectivity/mobility in WBAN applications through detachable wearable multi-band MIMO antenna

The connectivity and mobility of a miniaturized multi-band four-port textile leaky wave multiple-input multiple-output (MIMO) antenna designed on a layer of denim (εr = 1.6, tanδ = 0.006) is enhanced by integrating it with two detachable spiral buttons designed on circular PTFE substrate (εr = 2.1, tanδ = 0.001). The connectivity and mobility enhancement of the proposed antenna is evaluated in terms of radiation and diversity parameters. Nested hexagonal split rings behind the buttons, U-shaped slots on textiles, a comb-shaped neutralization network, and an aperture-coupled feed technique are utilized. The unique structure of the buttons on a rigid substrate and the leaky wave antenna on the textile and their integration, the periodic nested elliptical and circular split ring resonators (CSRRs) slots on the aperture coupled to ground, are to expand the connectivity and mobility of the proposed MIMO antenna by offering multiple bands, higher isolation, broadside radiation, and low specific absorption rate (SAR). The leaky wave and button antennas have dimensions of 40 × 30 × 1 mm3 and a diameter of only 13 mm, respectively. The operational bands are 0.86–2.75 GHz, 2.9–4.85 GHz, 5.75–6.15 GHz, and 8–9.85 GHz, covering the L, C, S, and X bands. Additionally, diversity performance is evaluated by defining the envelope correlation coefficient (ECC), diversity gain (DG), Channel Capacity Loss (CCL), and mean effective gain (MEG). The simulation and measurement findings are in good agreement. Following that, it offers a maximum gain of 8.25 dBi, low SAR (<0.05), an ECC below 0.05, DG above 9.85 dB, CCL< 0.25 bits/s/Hz, MEG <−3 dB, Circular polarization (CP), and strong isolation (>22 dB) between every two ports. These features make the proposed antenna an ideal option for MIMO communications and suitable for wireless local area network (WLAN) and fifth-generation (5G) communications.

Decoupling analysis for different exciting modes in MIMO DRA using absorbing surface walls

SummaryIn this paper, a decoupling mechanism is discussed for different mode excitations in the cylindrical dielectric resonator antenna (cDRA) by utilizing absorbing surface wall. In the cDRA, the fundamental radiating mode is HE11δ. Another higher order mode for radiation purpose in cDRA is HE12δ. Both HE11δ and HE12δ create broadside radiation. To analyze multiple‐input multiple‐output (MIMO) performance, two different dual‐port DRAs are proposed. Each antenna structure consists of two DRA with dual similar ports supporting the same mode. Therefore, two different antenna structures are proposed for two different modes. For each antenna, two 2 × 3 absorber array walls are designed, and they are placed in between the DRA to reduce the mutual coupling. When the absorber array walls are placed in between the antenna elements, they blocked the free‐space electromagnetic (EM) field interaction in between the DRA. Due to the reduction of free‐space radiation interaction, the mutual coupling between the ports is improved tremendously. For both HE11δ and HE12δ modes, the mutual coupling is reduced by more than 10 dB. To analyze efficacy of the proposed method, the antenna structure featuring the HE11δ mode is fabricated and experimentally tested.

Quad port P-shaped MIMO antenna array for 60 GHz applications

This article describes the design and fabrication of a 4 × 4 MIMO antenna array intended for operation at 60 GHz. The antenna comprises of half-circular p-shaped radiator connected with a microstrip line printed on the Rogers 4003 substrate of area 22.5 × 22.5 mm2 with εr, thickness, and tan δ of 3.5, 0.203 mm, and 0.0027, respectively. This single radiator is doubled and connected to the power divider to obtain a 1 × 2 antenna array for gain enhancement purposes. The array model is duplicated on the same substrate to achieve 2 ports and 4 ports MIMO antenna. Thereafter, the model is experimentally fabricated and tested to validate the simulated results. The measured results demonstrate the antenna's 60 GHz operating bandwidth extended from 57 GHz to 63 GHz and with insertion losses ≤ −30 dB between ports (1,2) and (1,4) (the orthogonal ports), while it equals around ≤ −23 dB between ports (1,3) (the mirrored ports) within the achieved band with good consistency between both simulated and tested results. Also, it has achieved a gain of more than 9 dBi at 60 GHz with a broadside radiation pattern in both planes. Furthermore, the MIMO parameters are also carried out (ECC, DG, CCL, MEG, and TARC). The ECC is below 0.0025, the DG is approximately 10 dB, the CCL is below 0.2 bits/s/Hz, the MEG is −3 dB and the TARC is below −10 dB over the achieved frequency band. All the MIMO parameters are investigated to prove the diversity characteristics of the antenna array which supports the antenna to be suitable for the 60 GHz communication.

Two port high gain and low mutual coupling dielectric resonator based array antenna for 5G mm-wave applications

In this communication, a two-port ceramic based array radiator at mm-wave frequency range is structured and analysed. 3-dB power divider based microstrip feed line is utilised to excite the rectangular aperture. The same aperture is used to feed the ceramic, which creates fundamental hybrid mode (HEM11δ ) inside the dielectric resonator. Feeding structure is designed on RT Duroid substrate having thickness 0.254 mm and permittivity 2.2. The length and width of the substrate is 60.0 mm and 30.0 mm respectively. Alumina material is used to design the ceramic having permittivity 9.8. The exclusive feature of the proposed antenna design is to get highly directional pattern along with high gain (more than 13.5 dBi) in mm-wave frequency range with the assistance of 1*4 array structure. Orthogonal orientation of antenna ports adds the polarization diversity concept, which in turns improve the isolation level more than 50 dB. Measured results confirm that the designed antenna works effectively in between 31.5–32.8 GHz. Broadside radiation pattern and good value of Envelop correlation coefficient (less than 0.1)/Diversity gain (10.0 dB) make the designed antenna employable for n257 frequency band of 5G mm-wave applications.

A single-layer multimode high gain circularly polarized metasurface antenna using CMA for C-band applications

Abstract This article presents an innovative design for a low-profile, high-gain circularly polarized (CP) antenna using a single-layer metasurface (MTS). The proposed design incorporates an MTS layer, comprising a 4 × 4 array of hexagonal-shaped patches, printed on the top layer of the substrate. The bottom layer features a coplanar waveguide-fed slotted ground. Circular polarization and broadside radiation are achieved through the application of characteristic mode analysis (CMA). CMA is employed to simultaneously excite desired modes, aiming for wideband circular polarization and gain enhancement. Experimental results validate the effectiveness of the design, with compact dimensions of 0.67λ0 × 0.67λ0 × 0.04λ0. The measurements demonstrate an impressive impedance bandwidth of 84.3% within the 3.7–9.1 GHz. Additionally, a 3-dB axial ratio bandwidth of 18.6% is observed between 4.96 and 5.98 GHz and 3.74% between 8.38 and 8.7 GHz. The antenna exhibits excellent radiation pattern characteristics, featuring a maximum gain of 10.08 dBi at 7.1 GHz. The radiation pattern is symmetrical with broadside directionality, making the antenna well-suited for sensing applications.

Design and investigation of cavity backed bowtie antenna with unidirectional radiation pattern using characteristic mode analysis

Abstract In this work, a novel cavity backed leaf-shaped bowtie antenna is designed using Characteristic Mode Analysis (CMA). An analytical expression is proposed to arrive at the leaf shape of the bowtie antenna using optimization process. The developed antenna is backed by a square-cavity to get unidirectional radiation pattern with high gain and good front-to-back-ratio characteristics. CMA technique is used in the design and optimization of the cavity structure and generalized design equation is proposed to design the cavity for getting good impedance bandwidth and broadside radiation characteristics in the Desired Band of Interest (DBI). The developed antenna resonates from 0.8 to 4.3 GHz with stable and unidirectional radiation characteristics giving maximum gain and FBR of 11.5 dBi and 15.2 dB respectively, making it suitable for Ground Penetrating Radar (GPR) applications.

A Circularly Polarized Complementary Antenna with Substrate Integrated Coaxial Line Feed for X-Band Applications

This work presents a design for a complementary antenna with circular polarization that has a wide operating bandwidth, stable broadside radiation, and stable gain for X-band applications. The proposed antenna consists of an irregular loop and a parasitic electric dipole, which work together to produce equivalent radiation from the magnetic and electric dipoles. By arranging the dipole and the loop in a specific geometry, this antenna effectively generates circularly polarized wave propagation. A substrate integrated coaxial line (SICL) is applied to feed the antenna through an aperture cutting on the ground. The proposed antenna achieves a wide axial ratio (AR) and impedance bandwidths of 27.4% (from 8.5 to 11.22 GHz, for the AR ≤ 3 dB) and 39.6% (from 7.5 to 11.2 GHz, for the reflection coefficient ≤ −10 dB), respectively. Moreover, the antenna maintains a stable broadside radiation pattern across the operating bandwidth, with an average gain of 10 dBic. This proposed antenna design is competitive for X-band wireless communications.