Showing papers on "Patch antenna published in 2020"

A Metasurface-Based Low-Profile Wideband Circularly Polarized Patch Antenna for 5G Millimeter-Wave Systems

Abstract: This paper presents the design and realization of a metasurface-based low-profile wideband Circularly Polarized (CP) patch antenna with high performance for Fifth-generation (5G) communication systems. The antenna consists of a modified patch, sandwiched between an array of $4\times4$ symmetrical square ring Metasurface (MTS) and a ground plane. Initially, the intrinsic narrow bandwidth of the conventional patch antenna is increased using a diagonal rectangular slot. For further performance enhancement, the additional resonances and CP radiations are achieved for wideband operation in terms of impedance and Axial Ratio (AR) by effective excitation of surface waves propagating along the MTS. The stacking of MTS on the modified patch without any air gap resulted in an overall compact size of $1.1\lambda _{0} \times 1.1\lambda _{0} \times 0.093\lambda _{0}$ . Simulated and measured results show that the MTS-based antenna offers a wide impedance bandwidth ranging from 24 – 34.1 GHz (34.7%) for $\vert \text{S}_{11}\vert with a maximum gain of 11 dBic and a 3-dB AR bandwidth of 24.1 – 29.5 GHz (20.1 %). Moreover, the proposed antenna has a smooth gain response with a small variation in its gain (9.5 – 11 dBic) and a stable left-hand CP radiation in the desired frequency range. The operating bandwidth of this antenna is covering the proposed entire global millimeter-wave spectrum (24.2 – 29.5 GHz) for 5G communication systems.

Millimeter-Wave Dual-Polarized Filtering Antenna for 5G Application

Abstract: This article presents a novel dual-polarized millimeter-wave (mm-Wave) patch antenna with bandpass filtering response. The proposed antenna consists of a differential-fed cross-shaped driven patch and four stacked parasitic patches. The combination of the stacked patches and the driven patch can be equivalent to a bandstop filtering circuit for generating a radiation null at the upper band edge. Besides, four additional shorted patches are added beside the cross-shaped driven patch to introduce another radiation null at the lower band edge. Moreover, by embedding a cross-shaped strip between these four stacked patches, the third radiation null is generated to further suppress the upper stopband. As a result, a quasi-elliptic bandpass response is realized without requiring extra filtering circuit. For demonstration, a prototype was fabricated with standard PCB process and measured. The prototype operates in the 5G band (24.25–29.5 GHz) and it has an impedance bandwidth of 20%. The out-of-band gain drops over 15 dB at 23 and 32.5 GHz, respectively, which exhibits high selectivity. These merits make the proposed antenna a good element candidate for the 5G mm-Wave massive MIMO applications to reduce the requirements of the filters in the mm-Wave RF front ends.

Weak-Field-Based Self-Decoupling Patch Antennas

Abstract: In this article, a new self-decoupling method, namely weak-field-based decoupling technique, is proposed and validated based on inset-fed patch antenna arrays. The self-decoupling effect is realized by taking advantage of the inherent weak-field area created by the feeding structure and proposed inset-fed patch. By strategically arranging the array element in the weak-field area of the adjacent antenna element, the coupling strength between adjacent elements can be controlled under a very low level without the need of any additional decoupling circuitry or structures. A two-element patch antenna array was first developed and analyzed, achieving a peak isolation level of 61 dB. Afterward, a four-element linear patch antenna array was designed, fabricated, and measured to further validate the proposed technique. With the distinct advantages of simple structure and effective isolation enhancement, the proposed self-decoupling method is very promising for MIMO applications.

Metamaterial-Inspired Antenna Array for Application in Microwave Breast Imaging Systems for Tumor Detection

Abstract: This paper presents a study of a planar antenna-array inspired by the metamaterial concept where the resonant elements have sub-wavelength dimensions for application in microwave medical imaging systems for detecting tumors in biological tissues. The proposed antenna consists of square-shaped concentric-rings which are connected to a central patch through a common feedline. The array structure comprises several antennas that are arranged to surround the sample breast model. One antenna at a time in the array is used in transmission-mode while others are in receive-mode. The antenna array operates over 2–12 GHz amply covering the frequency range of existing microwave imaging systems. Measured results show that compared to a standard patch antenna array the proposed array with identical dimensions exhibits an average radiation gain and efficiency improvement of 4.8 dBi and 18%, respectively. The average reflection-coefficient of the array over its operating range is better than S11 ≤ −20 dB making it highly receptive to weak signals and minimizing the distortion encountered with the transmission of short duration pulse-trains. Moreover, the proposed antenna-array exhibits high-isolation on average of 30dB between radiators. This means that antennas in the array (i) can be closely spaced to accommodate more radiators to achieve higher-resolution imaging scans, and (ii) the imagining scans can be done over a wider frequency range to ascertain better contrast in electrical parameters between malignant tumor-tissue and the surrounding normal breast-tissue to facilitate the detection of breast-tumor. It is found that short wavelength gives better resolution. In this experimental study a standard biomedical breast model that mimics a real-human breast in terms of dielectric and optical properties was used to demonstrate the viability of the proposed antenna over a standard patch antenna in the detection and the localization of tumor. These results are encouraging for clinical trials and further refinement of the antenna-array.

A Compact Single-Layer Wideband Microstrip Antenna With Filtering Performance

Abstract: A compact single-layer filtering microstrip antenna with diverse characteristics of low profile, high gain, wide band, and high selectivity is proposed in this letter. Simple structure as it is, the presented antenna mainly consists of a rectangle driven patch, four parasitic strips, a pair of symbiotic strips, and a set of shorting pins. By attaching four parasitic strips to the original rectangular patch antenna, an additional resonance can be excited while the high-band edge selectivity is greatly improved due to the formation of a radiation null outside. Then, two symbiotic strips are embedded on both sides of the driven patch, which in turn creates an extra resonance mode and a lower-band radiation null. The set of shorting pins are applied to further improve operating and filtering response. Finally, the use of two parasitic patches can effectively improve the level of impedance bandwidth (IBW) and upper-band suppression. To verify this design, the corresponding antenna is fabricated and tested. The measured and simulated results are highly consistent, which reveals that it owns a wide IBW of 20.1% (2.19–2.68 GHz) with three resonance points, a higher average gain larger than 9.5 dBi, and a flat radiation efficiency above 88% in-band. The suppression level of the out-of-band gain on both sides can reach 14.5 dB.

A Gain-Enhanced Slotted Patch Antenna Using Metasurface as Superstrate Configuration

Abstract: In this paper, a novel, compact, high-gain, directive, and superstrate configuration-based metasurface (MS) antenna has been designed, which incorporates a fractal-shaped slotted patch having a periodic arrangement of square patches along with a shorting via at its center and a couple of rectangular slots in the ground plane. The MS is designed over the FR4 dielectric by introducing a periodic arrangement of unit cells in which the unit cell is structured by a C-type patterned patch in the center surrounded by a couple of L-type-shaped patches. The MS is separated by a layer of Teflon from the conventional patch antenna designed over the FR4 dielectric, thereby acting as a superstrate. The proposed antenna provides good impedance matching across the frequency region of 10.14–10.94 GHz with a unidirectional radiation pattern. A fractional bandwidth of 7.6% and a maximum return loss of 24 dB have been realized at 10.44 GHz. The measured realized gain of 7.57 dBi was obtained at the same operating frequency. As the proposed antenna is more efficient, it can be promoted for $X$ -band operations, such as satellite communication, defense purpose, and medical supervision.

A Novel Dual-Band (38/60 GHz) Patch Antenna for 5G Mobile Handsets

Abstract: A compact dual-frequency ( 38 / 60 GHz ) microstrip patch antenna with novel design is proposed for 5G mobile handsets to combine complicated radiation mechanisms for dual-band operation. The proposed antenna is composed of two electromagnetically coupled patches. The first patch is directly fed by a microstrip line and is mainly responsible for radiation in the lower band ( 38 GHz ). The second patch is fed through both capacitive and inductive coupling to the first patch and is mainly responsible for radiation in the upper frequency band ( 60 GHz ). Numerical and experimental results show good performance regarding return loss, bandwidth, radiation patterns, radiation efficiency, and gain. The impedance matching bandwidths achieved in the 38 GHz and 60 GHz bands are about 2 GHz and 3.2 GHz , respectively. The minimum value of the return loss is − 42 dB for the 38 GHz band and − 47 for the 60 GHz band. Radiation patterns are omnidirectional with a balloon-like shape for both bands, which makes the proposed single antenna an excellent candidate for a multiple-input multiple-output (MIMO) system constructed from a number of properly allocated elements for 5G mobile communications with excellent diversity schemes. Numerical comparisons show that the proposed antenna is superior to other published designs.

Circularly Polarized Fabry-Perot Antenna Employing a Receiver–Transmitter Polarization Conversion Metasurface

Abstract: This study presents a linear-to-circular polarization conversion metasurface (PCM) based on a novel unit cell for a circularly polarized (CP) Fabry-Perot (FP) antenna. The unit cell consists of a bottom linear-polarization patch and a top circular-polarization patch, which are separated by a metalized plane and connected by a metalized via. The bottom patch receives the power and transfers it to the top layer through the metalized via; the top layer then transmits the power into space. The metasurface is designed to have high reflectivity and an appropriate reflection phase to compose a resonate cavity with the ground plane. The capability of linear to circular polarization conversion is provided to the PCM by adjustment of the transmission magnitude and phase. A slot coupled patch antenna is used as the feeder due to its stable broadside radiation. The linearly polarized wave emitting from the feeder resonates in the cavity and then is converted into a CP wave when it comes out of the cavity. A prototype antenna is fabricated and measured. The measurement results show that the antenna has good circular polarization performance within the band of 9.8–10.2 GHz. The maximum gain of the antenna reaches 17.8 dBic at 10 GHz, with an aperture efficiency of 53%. The proposed antenna outperforms most of the previously reported CP FP antennas due to its low profile, high gain, and relatively high efficiency.

Dual-Polarization Wideband Sub-6 GHz Suspended Patch Antenna for 5G Base Station

Abstract: This letter presents a simple, compact, low-cost, low-profile, dual-polarization, suspended patch antenna design to operate in 3.3−3.8 GHz band for 5G base stations. The proposed antenna comprises a main radiating patch, a secondary parasitic patch, modified L-probe feeds, and a vertical metal wall. The main patch is capacitively driven by two feeds for dual (±45° slant) polarization. The vertical metal wall is used to increase the port isolation. The parasitic patch also helps further improvement of input impedance matching (| S 11|, | S 22|) and port isolation (| S 21|). The prototyped antenna has | S 11|, | S 22| S 11|, | S 22| S 21| E- /- H -planes. The gain of the antenna is 8.95 ± 0.25 dBi. Numerical calculations and experimental results are reported and discussed.

A Wideband Circularly Polarized Implantable Patch Antenna for ISM Band Biomedical Applications

Abstract: This communication presents a novel compact broadband circularly polarized (CP) implantable patch antenna for biomedical applications in 2.4 GHz industrial, scientific, and medical (ISM) band. By employing slots on the patch plane and shorting method, the whole size (including the superstrate) of the designed antenna can be enormously reduced to $9.8\times 9.8\times1.27$ mm3, which is equivalent to $0.0784\lambda _{0}\times 0.0784\lambda _ {0}\times 0.0102\lambda _ {0}$ ( $\lambda _ {0}$ is the free-space wavelength at 2.4 GHz). Under the premise of keeping a slotless ground, not only a good size reduction is realized but also the impedance bandwidth and the axial ratio (AR) bandwidth are greatly improved. A simulated −10 dB impedance bandwidth of 21.5% with a 3 dB AR bandwidth of 15.8% is acquired in a skin phantom. The antenna also exhibits good robustness to different thicknesses of biocompatible coating. The influence of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The experiments are carried out in both skin-mimicking gel and pork, and the respective measured impedance bandwidths are 25.9% and 25.7%. The CP purity is experimentally validated by comparing the communication link levels in two orthogonal polarization directions. The maximum specific absorption rate (SAR) value satisfies the IEEE standard safety guidelines.

Compact Absorptive Filtering Patch Antenna

Abstract: This article presents a compact absorptive filtering patch antenna. It consists of a filtering patch antenna and a bandstop filter (BSF), with their transfer functions being complementary to each other. A slot is fabricated in each of the patch and ground, giving a total of two radiation nulls for the lower bandedge. By using a dual-stub feed, two radiation nulls are also obtained for the upper bandedge. For the BSF, a $\lambda _{\mathrm {g}}$ /2 defected ground structure (DGS) and a $\lambda _{\mathrm {g}}$ /4 defected microstrip structure (DMS) are used in the design. It is terminated by a chip resistor. Since the filtering patch antenna and BSF have complementary transfer functions, the incident energy can be radiated effectively in the passband but largely absorbed by the resistor in the stopbands. As a result, only little energy will be reflected over a wide frequency range, giving a reflectionless characteristic. To demonstrate this idea, an absorptive filtering antenna operating at 5.8 GHz was designed, fabricated, and tested. Its impedance is matched from 5 to 6.5 GHz, with the measured out-of-band suppression being higher than 17 and 20 dB for the lower and upper stopbands, respectively. The measured peak realized gain is 7.28 dBi.

A Jia-shaped artistic patch antenna for dual-band circular polarization.

Abstract: This article presents a novel single-feed circularly polarized patch antenna for dual-band (2.6 and 3.4 GHz) applications. Details of the design procedure and design considerations of the proposed antenna are described. The novelties of the proposed antenna are counted by (i) a meaningful Jia-shaped patch used as the primary radiator; (ii) a 3D L-shaped feeding probe used to excite the stacked patches so that the near degenerate-modes are excited at the desired dual band; (iii) down-tilt beams achieved that are particularly suitable for wall-mount base-stations. The measured 3-dB axial-ratio bandwidths are 2.41–2.61 GHz and 3.25–3.42 GHz, where the maximum gains are recorded as 7.3 and 6.3 dBic, respectively. Methods for the adjustment of band ratio down to 1.18 are discussed. The overall antenna size is 100 × 100 × 12.8 mm3.

A Metamaterial-Based $S/X$ -Band Shared-Aperture Phased-Array Antenna With Wide Beam Scanning Coverage

Abstract: This article proposes an ultralow profile $S/X$ -band shared-aperture phased-array antenna (SAPAA), which can achieve wide beam scanning coverage in both the $S$ - and $X$ -bands. The SAPAA consists of an $S$ -band array with a triangular placement that has 11 elements and a grid array with $8\times 16\,\,X$ -band elements. To avoid grating lobes in wide beam scanning coverage, a metamaterial-based stacked mushroom structure is proposed to reduce the array spacing of the two bands, where an $X$ -band patch antenna is stacked on a traditional mushroom structure. A $4\times4$ subarray of the stacked mushroom structure operates as a single antenna element in $S$ -band. Consequently, each $S$ -band element corresponds to a $4\times4$ subarray of the $X$ -band element. Because a triangular arrangement in the $S$ -band array and a square arrangement in the $X$ -band array are employed, the array spacing of the two bands is $0.54\lambda _{\mathrm {L0}}$ and $0.51\lambda _{\mathrm {H0}}$ , respectively, which is suitable for wide beam scanning coverage. Moreover, the shorting pin of the mushroom structure is also the feeding pin of the $X$ -band patch. This structure reuse technology reduces the whole profile to less than $0.04\lambda _{0}$ . To verify this design, a prototype is fabricated through the multilayer printed circuit board process. It realizes ±50° beam coverage in both the $S$ - and $X$ -bands.

Circularly Polarized 2 Bit Reconfigurable Beam-Steering Antenna Array

Abstract: In this communication, a circularly polarized (CP) reconfigurable 2 bit antenna array is proposed for beam-steering applications. The proposed antenna array utilizes a novel CP reconfigurable 2 bit patch antenna as radiation element. For a reconfigurable 2 bit element, there should be four phase states (i.e., 0°, 90°, 180°, and 270°). In the proposed radiation element, a corner truncated microstrip patch antenna is presented for CP radiation. Owing to the symmetry of the patch antenna, the 0° and 180° phase states are achieved by selecting feeding points of the patch instead of using complex feeding network. A 90° digital phase shifter is cascaded to realize the 90° and 270° phase states for the 2 bit reconfigurable element. Based on the novel 2 bit CP element, an eight-element CP reconfigurable 2 bit antenna array is fabricated and tested to verify the design strategy at 3.65 GHz. The measured results match well with simulation. By appropriately controlling the ON and OFF states of p-i-n diodes, the proposed CP array can be steered from −49° to +49°.

Isolation Enhancement of Closely Packed Dual Circularly Polarized MIMO Antenna Using Hybrid Technique

Abstract: Mutual coupling always seriously degrades the antenna performance in multiple-input multiple-output (MIMO) systems but this issue has been rarely investigated for antennas with circular polarization. In this paper, a planar and compact circularly polarized MIMO patch antenna with the polarization diversity is presented. Three grounded stubs and a mirrored F-shaped defected ground structure are used to achieve simultaneous matching and isolation between the two patches with offset feeding for circular polarization. The antenna elements are closely packed with the edge-to-edge distance of $0.06\lambda _{0}$ at the desired frequency of 2.5 GHz. The measured results indicate that the proposed antenna achieves the impedance matching ( $\text{S}_{11} dB), high isolation ( $\text{S}_{12} dB), and circular polarization (axial ratio< 3 dB) within the frequency band of 2.5-2.55 GHz. The radiation patterns and realized gains are measured, showing good agreement between the simulation and measurement.

Patch Antenna Loaded With Paired Shorting Pins and H-Shaped Slot for 28/38 GHz Dual-Band MIMO Applications

Abstract: A novel dual-band patch antenna operating at 28/38 GHz is proposed for multiple-input multiple-output (MIMO) communication systems in this paper. The antenna utilizes substrate integrated waveguide (SIW) transmission line as the feed by means of a coupling slot on the SIW. A square patch antenna functions as the radiator for 28 GHz. The inductive loading, which presents as a pair of shorting pins in this design, achieves the impedance matching for 28 GHz-band. Etched on the square patch, the proposed H-shaped slot makes the radiator to performance as an antenna containing two radiating arms and thus introduces another resonant frequency at 38 GHz. Directions of the surface current on the paired arms are identical and produce a reasonable radiation pattern for 38 GH-band. Simulated results declare that the antenna achieves an $S_{11} dB bandwidth of 27.6 – 28.5 GHz (relative bandwidth of 3.2%) and 36.9 – 38.9 GHz (relative bandwidth of 5.3%), while simulated gain is 9.0 dBi at 28 GHz and 5.9 dBi at 38 GHz, respectively. Measured results have verified the feasibility and correctness of the proposed dual-band antenna, which indicate that the antenna is a promising candidate for MIMO communication systems at millimeter-wave (mmW) band.

Low-Profile Strip-Loaded Textile Antenna With Enhanced Bandwidth and Isolation for Full-Duplex Wearable Applications

Abstract: A novel dual-port textile antenna with a low profile and enhanced bandwidth is proposed for 2.45 GHz IMS-band full-duplex wearable applications. The antenna is developed on a textile material by using an advanced screen-printing technology and, thus, exhibits a very good structural flexibility and a high manufacturing accuracy. To improve the bandwidths at the two input ports, an innovative method is introduced for the first time where two additional strips are incorporated into the antenna design. These additional strips are placed perpendicularly to the feed lines to generate another resonant frequency, which is then combined with the fundamental mode of the patch antenna, producing the second-order resonant properties with enhanced bandwidths. The proposed strips are also beneficial to significantly improve the isolation between the two channels/ports. To maintain a robust linkage, a study of structural deformation is carried out by bending the antenna along both the 0° and 45° directions. The experimental results also show that the antenna is robust to the human tissue loading, where the specific absorption rate (SAR) is lower than 0.37 W/kg when the antenna is fully attached. The measured results agree reasonably well with the simulations providing experimental verification of the design concept. The antenna is believed to be the first dual-mode textile antenna of its type which features a low profile, improved bandwidth, high isolation, and low cost, making it a good candidate for potential full-duplex wearable applications.

Differential-Fed Dual-Polarized Dielectric Patch Antenna With Gain Enhancement Based on Higher Order Modes

Abstract: A differential-fed gain-enhanced dual-polarized dielectric patch antenna operating at higher order TM121 and TM321 modes is investigated in this letter. The introduction of grounded bars in a conventional square dielectric patch resonator (DPR) is a key technique in the proposed design. It not only moves the higher order TM121 mode upwards to enhance the gain of the antenna, but also enables the higher order TM321 mode to be excited and combined with TM121 mode to expand the bandwidth. Their corresponding degenerate modes in the DPR are used to generate a dual-polarized operation. By using two identical pairs of differential feeding lines to excite the proposed DPR, several advantages such as high isolation and low cross polarization can be obtained. For demonstration, an antenna prototype centered at about 4.9 GHz is implemented and measured. The simulated and measured results are given, showing a good agreement.

A Conformal Ultrawideband Antenna With Monopole-Like Radiation Patterns

Abstract: A simple conformal ultrawideband (UWB) antenna with monopole-like radiation patterns is proposed in this communication. To achieve the wide bandwidth, two rings are arranged concentrically around the main annular-ring circular patch antenna, in which two rectangular slots are added. The antenna has monopole-like radiation patterns generated by combining four propagation modes of TM01, TM02, TM03, and TM04 throughout the operating bands. To enhance the flexibility and robustness, the proposed antenna is fabricated using conductive fabric embedded into polydimethylsiloxane (PDMS) polymer. To our knowledge, this is the first flexible UWB antenna with monopole-like radiation patterns reported in the open literature. The measured results show that the antenna achieves a 10 dB return loss bandwidth from 2.85 to 8.6 GHz. Monopole-like radiation patterns are maintained throughout the frequency band, agreeing well with simulated results. This has been validated through the measured mean realized gain (MRG) pattern from 2.85 to 8.6 GHz. The fabricated antenna was bent and tested at various curvatures to verify its conformability. To evaluate suitability for UWB communications, the system-fidelity factors of the antenna are investigated using full-wave analysis in CST Microwave Studio, in both flat and bent conditions, validating its potential for UWB pulse transmission.

All-organic flexible fabric antenna for wearable electronics

Abstract: Next-generation wearable systems call for flexible, breathable, and skin-friendly wireless transmitters for realizing body area networks and the internet of things. This work presents the first fully functional, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) screen-printed fabric patch antenna for next-generation wearable antennas. This is an unparalleled milestone as prior conductive polymer based fabrics all demonstrated insufficient RF radiation due to skin effect loss, whereas here, an all-organic fabric RF transmitter is realized with the help of nanotemplate-assisted PEDOT:PSS conductive phase segregation on the surface of fabric fibers, forming a continuum coaxial structure with a conductive shell. This multi-strand wire structure endows the conductive fibers with a high surface area that is similar to high frequency Litz-wire, resulting in an extremely high RF conductivity. The fabricated patch antenna based on this conductive fabric shows an extremely low return loss of −50 dB and a satisfactory radiation efficiency of 28% at its resonant frequency of 2.35 GHz, and preserves its performance characteristics when bent over a representative phantom. In addition, the Doppler radar system based on the fabric patch antennas demonstrates satisfactory speed and distance detection with high precision, well suited for future application as a short-range sensing device for blind assistance. This development paves a new way to fabricate all-organic flexible RF devices for wireless communication with profound implications for the field of integrated wearable electronic networks.

Dual-Polarized Embroidered Textile Armband Antenna Array With Omnidirectional Radiation for On-/Off-Body Wearable Applications

Abstract: In this article, a novel dual-polarized embroidered textile antenna array with an omnidirectional radiation pattern is proposed for both on- and off-body wearable applications. The flexible antenna is composed of a group of circularly oriented dual-polarized patch antennas excited with uniform amplitude and phase. The antenna array can be wrapped around a cylinder, such as an arm or a leg, for realizing a quasi-omnidirectional radiation pattern in the azimuthal plane, which is highly desirable in both on-body and off-body wearable applications. The operating principles and design consideration for how to achieve the omnidirectional radiation and how to avoid radiation nulls are investigated in detail. Moreover, these analytical studies are verified through the experimental results. In addition, a dual orthogonal polarization capability is employed to improve the link reliability. Due to the high front-to-back ratio (FBR) exhibited by each patch antenna element, the proposed omnidirectional antenna array also features a low specific absorption rate (SAR) and high efficiency, which are extremely important for wearable applications. As a proof-of-concept, an antenna array prototype operating at 5.8 GHz is designed, fabricated, and tested. The measured results agree reasonably well with the simulations in terms of S-parameters, polarization isolation, and radiation patterns, demonstrating that the proposed antenna array is ideally suited for potential wearable applications.

Patch Antenna and Antenna Array on Multilayer High-Frequency PCB for D-Band

Abstract: This paper presents the design, manufacturing, and characterization of a wide-band cavity-backed aperture-coupled patch antenna and a 16-element antenna array on multilayer printed circuit board (PCB) targeted for D-band applications Microstrip line and grounded coplanar waveguide (GCPW) transmission lines are also designed and tested to investigate line losses at D-band The test structures are manufactured using printed circuit board technology with semi-additive processing (mSAP) of conductors on a multilayered substrate The measurement results indicate an insertion loss of 19 dB/cm for the microstrip line and 18 dB/cm for the coplanar waveguide at 150 GHz The measured maximum gains for single antenna and 16-element array are respectively 7 dBi and 14 dBi at 143 GHz The measured antenna input matching bandwidth is 20 GHz The results show the viability of advanced printed circuit technology for D-band transmission lines, antennas, and antenna arrays

Wideband Low-Profile Dielectric Patch Antenna and Array With Anisotropic Property

Abstract: A dielectric patch (DP) resonator (DPR) with silver-coated slots is investigated for designing wideband low-profile antenna in this communication. The low-profile DPR can be treated as an anisotropic dielectric resonator (DR) for analysis. A new equation for calculating the effective dielectric constant of the DPR operating at the TM modes is proposed. Based on this, the anisotropic property is investigated to enhance the gain of DP antenna (DPA). It is found from the theoretical analysis that the resultant antenna is a good compromise between the traditional microstrip patch antenna (MPA) and dielectric resonator antenna (DRA) in terms of profile, gain, efficiency, and design freedom. By making full use of the multimode characteristic of the DPR, the silver-coated slots are introduced on the DP to shift high-order TM121 mode close to TM101 mode. As a result, the bandwidth of the antenna can be significantly expanded. For demonstration, the DPA element and $1\times4$ array prototype operating in the microwave band (5 GHz) are implemented and measured.

High-Performance Graphene Patch Antenna with Superstrate Cover for Terahertz Band Application

Abstract: Graphene-based patch antennas are rapidly gaining interests in communication technologies for high-speed data transmission due to the exciting properties of graphene material. Herein, we designed a high-performance circular patch antenna for terahertz band application with graphene as the radiating patch. For the protection of patch against environmental jeopardies and enhancement of antenna performance, a thin layer of Teflon (er = 2.1) as superstrate is used, and overall antenna performance is evaluated. The designed antenna operates around 7 THz with amazing S11 of − 75.66 dB and VSWR of 1.0003. The designed antenna is highly efficient with radiation efficiency of 97.21% and a very high gain of 7.286 dB. The designed antenna is also analysed for different dielectric materials used as the covering superstrate layer. Where the introduction of higher dielectric constant materials as superstrate layer increases the antenna gain significantly, it also reduces the bandwidth and efficiency of the designed antenna at terahertz band. An antenna gain of 7.392 dB is achieved for glass (er = 4.82) as superstrate material.

A Topological Design Tool for the Synthesis of Antenna Radiation Patterns

Abstract: Patch antennas are among the most popular radiating elements, yet their quasi-2-D structure reduces the degrees of freedom available to tailor their radiation pattern. To overcome this limitation, a possible solution consists in etching on a grounded substrate two concentric radiating elements and combining two modes (one for each element) with proper amplitude/phase relations. Although this technique leads, in principle, to an infinite number of possible configurations (i.e., each patch element can support an infinite number of modes), the theoretical and experimental verifications available in the literature are limited to the first two radiating modes (TM11 and TM21) of a circular patch antenna. Recently, we have shown that the design of this circular patch can be effectively performed by exploiting the topological properties of vortex fields and, in particular, by controlling the phase singularity exhibited by the higher order right-handed circularly polarized (RHCP) TM21 mode of the circular patch. Since the number of RHCP higher order modes of a circular patch is infinite, we can in principle deal with an arbitrary number of phase singularity points, whose combined control leads to unprecedented possibilities to shape the radiation pattern of a circular patch. In this article, we present a complete design tool to determine the number and position of phase singularity points arising when combining the RHCP modes of a circular patch antenna and, eventually, manipulate them to synthesize the required radiation pattern. As a realistic application example, we show how the proposed tool can be used to effectively design a single antenna whose radiation pattern can be properly tailored to switch between two different states, i.e., a sector and a saddle shape, widely used in base stations for mobile and satellite communications, respectively.

Frequency and pattern reconfigurable rectangular patch antenna using single PIN diode

Abstract: The paper presents the design of a frequency and pattern reconfigurable rectangular patch antenna using a single PIN diode switch. The use of single PIN diode reduces the complexity of the biasing network required for the diode. The proposed antenna can work in two different modes and resonates at 2.47 GHz, 3.8 GHz, and 5.36 GHz with the capability to change the radiation pattern. In this design biasing lines required for biasing of the diode are placed away from the radiating structure and the pattern search algorithm is used for the optimization of antenna feed for achieving impedance matching. These are the two improvisations made in the presented design as compared to the existing designs in literature.

OAM-Generating Transmitarray Antenna With Circular Phased Array Antenna Feed

Abstract: A transmitarray antenna (TAA) with a small-scale circular phased array antenna (PAA) feed is proposed in this article to generate orbital angular momentum (OAM)-carrying radio beams. After analyzing the operating mechanisms of the OAM-generating PAA-fed TAA, its numerical model is further developed to determine the TAA element arrangement and the PAA feed excitation coefficients. Furthermore, a three-layer element with polarization-conversion property and the traditional patch antenna element are identified as the elements of the TAA and PAA feed, respectively. Benefiting from the intrinsic multibeam capabilities of the TAA, the steering of the zero-OAM-mode beam is firstly discussed, where a conical scanning across an angular range of ±25° is realized. Meanwhile, the creation of multiple pure or mixed OAM beams with helical phase fronts is also presented, where the superposition of multiple OAM states provides more possibilities to increase the channel capacity and spectrum efficiency. To facilitate the experiments, an $8\times 8$ Butler matrix with a bandwidth over 30% is designed, which integrated with the array-fed TAA also provides an attractive solution to simultaneously generate multiple OAM modes without requiring any active modules. The experimental results agree reasonably well with the numerical ones, validating the feasibility of our idea to design a high-gain OAM-generating PAA-fed TAA.