Conformal Antenna Array Research Articles

Wide scan angle multibeam conformal antenna array with novel feeding for mm-wave 5G applications

This paper presents a low-profile wide scan angle multibeam conformal antenna array system with a novel feeding network for 28 GHz mm-wave 5G applications. The proposed antenna system utilizes two conventional branch-line couplers as its beamforming network. A novel feeding technique is applied to generate 7 beams with these couplers that are usually capable of generating 2 beams. The proposed solution provides a wide scanning range with a minimum realized gain of 5 dBi from −90° to 90° owing to this feeding approach and the peculiar placement of the array elements on a 0.15 mm thick R-F775 bendable substrate. The generated beams at their steer direction have the minimum and maximum gain values of 6.5 dBi and 9.7 dBi, respectively. A low-cost PCB manufacturing technique based on soft lithography and wet etching is used. The system dimensions excluding extra connector sections are 67×15×3mm3. The proposed flexible design is suitable for lightweight 5G communication systems and handsets with its compact low-complexity beamforming network, and wide 180° continuous covering angle.

A Wideband Conformal Array Antenna With Dual-Polarized Transmission and Reflection Element for Full-Space Beam-Scanning Capability

A Wideband Conformal Array Antenna With Dual-Polarized Transmission and Reflection Element for Full-Space Beam-Scanning Capability

Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

A low profile, vertically polarized, ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency (UHF) band is developed in this paper. The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height. Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension. Simulated results show that when the antenna array operates in a frequency range of 300 MHz–900 ​MHz, the end-fire radiation pattern achieves ±45° scanning range in the horizontal plane. Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array (1×2) are fabricated and validated. The end-fire antenna array should be suitable for airborne applications where low profile and conformal scanning phased antenna arrays with end-fire radiations are required. This design is attractive for airborne platform applications that are used to search, discover, identify, and scout the aerial target with vertically polarized beams.

A Subarray Selection Scheme for Cellular-Connected UAV With Conformal Phased Array Antenna

A Subarray Selection Scheme for Cellular-Connected UAV With Conformal Phased Array Antenna

A Tiling Method for Sub-Arrayed Spherical Conformal Phased Array Antennas Based on Maximum 3-D Space Entropy Model

A Tiling Method for Sub-Arrayed Spherical Conformal Phased Array Antennas Based on Maximum 3-D Space Entropy Model

Dual-Band Omni-Directional Scanning Conical Conformal Phased Array Antenna

Dual-Band Omni-Directional Scanning Conical Conformal Phased Array Antenna

A Fast Compensation Method for Deformed Conformal Antenna Arrays Considering Mutual Coupling Effect

A Fast Compensation Method for Deformed Conformal Antenna Arrays Considering Mutual Coupling Effect

Low-profile Circularly Polarized Conformal Antenna Array with Side Lobe Suppression for Vehicular SATCOM Applications

A circularly polarized microstrip antenna array with low side lobe levels is proposed for Vehicular Satellite Communication. The suppression of side lobe levels is accomplished by the non-uniform power distribution utilized to feed the individual patch elements. Impedance matching is ensured by the incorporation of a quarter-wave transformer via a microstrip line fed to the edge of the patch. When the proposed amplitude-weighted feed is compared to the conventional corporate feed, simulation results indicate a reduction in side lobe levels of 8.9 dB. The proposed antenna is constructed out of RT/DUROID 5880 material, which is lighter, more flexible, and less expensive than ceramic materials. The radiation characteristics of the proposed antenna are compared when the antenna is planar versus when it is made to conform to the roof of the vehicle. The measured results indicate a reflection coefficient at the resonant frequency of -31.5 dB and -27.7 dB when conformal, an impedance bandwidth of 410 MHz and 180 MHz when conformal, an axial ratio bandwidth of 140 MHz and 170 MHz when conformal, and a peak gain of 15.719 dB and 14.335 dB when conformal. The measured results validate the simulation results that this proposed antenna is appropriate for a variety of Vehicular Satellite Communication applications.

A Balloon Conformal Array Antenna of Broadened Bandwidth, High Gain, and Steerable Directional Beam Fed by a Flexible Phase Shifting Network

A Balloon Conformal Array Antenna of Broadened Bandwidth, High Gain, and Steerable Directional Beam Fed by a Flexible Phase Shifting Network

A wideband cylindrical conformal microstrip mimo antenna array

AbstractIn this paper, a wideband cylindrical conformal microstrip antenna array employing a proximity‐coupled feeding mechanism with a cavity‐backed configuration is designed and fabricated. Compared with other conformal microstrip patch antennas by using linear subarrays assembled piecewise, this design uses Teflon instead of traditional dielectric layers, and makes it possible to process the whole conformal array without splicing, obtaining the freedom in unit size and array radius adjustment except ease of manufacturing and assemblage. Combined with the optimization of the cavity size, an array with 4 × 4 elements is obtained which has a bandwidth of 40% from 8 to 12 GHz and a gain of 16.4 dB.

Radiation Pattern Synthesis Using Constraint Convex Optimization Algorithm for Conformal Antenna Array

In this paper, a model based on constraint convex optimization is proposed for the radiation pattern synthesis in cylindrical and spherical microstrip conformal array antennas. The optimization algorithm is modeled to decrease the Euclidean distance between the obtained radiation pattern of the deformed array and the desired radiation pattern of the planar array by calculating the suitable amplitude and phase values for the individual array patches. Four prototypes of 2×2, 3×3, 4×4, and 5×5 microstrip patch array antenna are used as the radiating elements which are deformed from planar arrangement and placed on the faces of prescribed spherical and cylindrical shapes with various radii of curvatures. The results reveal that the performance of optimization algorithm performs better in 5×5 array, followed by 4×4 array, 3×3 array, and 2×2 array. However, 5×5 array provides more degrees of freedom for tuning the radiation pattern in desired form. The 5×5 array computes suitable amplitude and phase values for the radiating elements of the array, which restore the radiation pattern in terms of mainlobe reconstruction, null locations, sidelobe levels, up to the deformation of 20 cm in both spherical and cylindrical configurations of conformal array. The proposed optimization technique when applied to conformal antenna array offers fast computational speed and good convergence accuracy for radiation pattern synthesis, which can be useful for various engineering applications.

Dual-Polarized Conformal Transparent Antenna Array With Hemispherical Beam Coverage

Dual-Polarized Conformal Transparent Antenna Array With Hemispherical Beam Coverage

Wide-Angle Scanning Microstrip Patch Antenna Array for mmWave Applications with High Gain

This paper presents a modified rectangular microstrip patch antenna (MRMPA) array conforming to the hemisphere for wide-angle beam scanning. Two different conformal antenna array designs are presented in this work. The first of these designs, a 13-element MRMPA array conformal to the surface of a circular arc, and the second one, a 9-element array conformal to the surface of a hemisphere, are designed and optimized. The geometrical approach of calculating the phase value is used to calculate the phase value of each antenna. The simulated results show that the 13-element conformal MRMPA array is achieving a beam scanning angle of ±84° with a gain of 13.89 dBi with low side lobe levels, and further, the gain of the array is enhanced by a dielectric superstrate that improved the gain by ∼2 dBi at all the scanning angles. Second, an MRMPA array conformal to a hemisphere with nine elements is designed with beam scanning ability from φ = 0°−360° and θ = ±30° with a gain of 15.69 dBi, and further, the gain is enhanced by ∼3 dBi with the dielectric superstrate. Full-wave simulations have proven both designs to be accurate and aligned with theoretical calculations.

Simple Matrix Equation (SME) Method for Pattern Synthesis of Conformal Antenna Array with Arbitrary Architecture

A novel noniterative method for pattern synthesis of conformal antenna array is put forward. First, a new pattern function formula for general conformal antenna array is derived. Then, according to the new pattern function formula, a new block matrix equation (BME) and a simple matrix equation (SME) are obtained. SME has the same form as the equation of linear array pattern synthesis. The new method can be applied to pattern synthesis of any conformal array. Moreover, due to SME having the same form as the matrix equation of linear array pattern synthesis, the new simple matrix equation can be dealt with by the approaches for linear array pattern synthesis, which significantly expands the existing approaches for conformal antenna array pattern synthesis. Two different conformal array configurations are taken as the examples to demonstrate the advantages of the new method. Results of the simulations show that the new method can flexibly and effectively be applied to synthesize patterns for various conformal array architectures.

A Bendable Wideband Dual-Polarization Conformal Phased-Array Antenna

In this letter, we proposed a bendable wideband dual-polarization low-profile conformal phased array antenna. The antenna element is an Invert-F fed stacked-patch antenna. It provides an active VSWR < 3 for 10.7 GHz to 12.75 GHz in the principal planes. The proposed phased array antenna employs a row modular architecture, which enables it to bend to a cylindrical geometry. Both the antenna aperture and the active components of the conformal phased array antenna are considered for bending in the letter. A prototype conformal phased array antenna with 8 rows of 4 dual-polarization antenna element was fabricated, assembled and measured. Wide-angle beam scanning is achieved by electronically scanning along the curved axis of the cylindrical conformal phased array antenna. Moreover, there is no grating lobe when scanning down to 60°.

Compact Additively Manufactured Conformal Slotted Waveguide Antenna Array

In this work we present the design and fabrication in metallic 3D-printing of a compact conformal slotted waveguide antenna array operating in the Ku-band. The application objective, although not limited only to this, is the optimisation of an antenna element which by stacking will be able to form a quasi-cylindrical sector. A beamforming network will be used for beam-steering in the elevation plane as coverage in the azimuthal plane is guaranteed by the conformal geometry. The compact design of the antenna element is therefore of great significance. For this reason, a direct feeding scheme by a coaxial connector is adopted. The antenna has been optimized following multiple parametric analyses of its geometrical parameters for the enhancement of the bandwidth, return losses and realized gain. The antenna was fabricated with Selective Laser Melting in aluminium and the experimental results agree well with the numerically calculated ones. The proposed CSWAA exhibits a reflection coefficient below -10 dB, realized gain above 14 dBi, as well as good cross-polarization and side-lobe level over a relative bandwidth of 8%.

A Conformal Phased Array Antenna with Improved Gain on a Cylindrical Surface

The manuscript reports phase compensation technique for improving the directionality and gain of a conformal phased array antenna on a cylindrical surface while steering the beam. The investigation reports two different components of phase compensation required for enhancing the directionality: (i) compensation required to mitigate the effect due to the vertical displacements of antenna elements on the conformal surface and (ii) additional phase shift required to align the broadside of each element in the direction of scan angle. It is highly effective in the restoration of the beam of a phased array mounted on conformal surfaces of a smaller radius causing significant deformation in the radiation pattern. The proposed formulation is implemented through Matlab and verified using CST for a 1-D circumferential phased array with 7 elements of a rectangular patch antenna of dimensions L = 8.72 mm and W = 14.52 mm designed for 10 GHz on a cylindrical surface of 10 cm radius. The model is also applicable to a Concave conformal phased array and can be extended to 2-D arrays. To the best of our knowledge, this is the first report on such a study and will find direct applications in the design and development of conformal phased arrays with high directionality and gain.

Millimeter-Wave Wide-Angle Scanning Phased Array Antenna Based on Heterogeneous Beam Elements

By imitating the element inclined beam distribution of a curved surface conformal (CSC) phased array antenna (PAA), a pseudo-curved surface conformal (PCSC) PAA realizes wide-angle scanning while maintaining a planar low profile. Inspired by the PCSC PAA, this communication proposes a PAA based on heterogeneous beam elements (HBEs) to realize wide-angle scanning. Using HBEs introduces a new design degree of freedom (DoFs), namely the element beam shape, to PAA. By optimizing HBEs and their arrangement, the effective aperture of a PAA can be increased at large scanning angles, and thus the scanning range can be improved. To verify the idea, first, a wide-beam 1×4-element subarray is developed. Then, a standard 4×4-element PAA is implemented using four uniform 1×4-element subarrays, achieving a >±60° 3-dB gain variation scanning range. At last, based on the standard PAA, by adjusting its structure to tailor four subarrays’ beam inclinations, a 4×4-element HBE PAA is designed. It further improves the scanning range to >±70° at an average cost of ~1.5dBi broadside scanning gain within the 5G mmWave band (24.25-29.5GHz, 19.5%). To the authors’ best knowledge, compared with the former planar mmWave PAAs, the proposed design shows the widest scanning range in a wide bandwidth.

Multiband Pattern Synthesis of Time-Modulated Conformal Array with Quadratic Convex Optimization Algorithm

Aiming at the multiband pattern synthesis problem of time-modulated conformal array antenna, a quadratic convex optimization algorithm is proposed for sum and difference beamforming with low sidelobe levels. This articles method synthesizes a difference beam with a low sidelobe level by generating nulls at the center frequency band and optimizing the switch-on duration time of array elements. And the sum beamforming and sidelobe suppression of the first-order sideband are realized by optimizing the switch-on instant time of the array elements. The proposed algorithm has excellent properties of sidelobe suppression and angular sweep. The simulation results of circular and satellite array antenna verify the effectiveness of the algorithm.

Modeling the effect of bend radius on the performance of a conformal dual-band mm-wave patch antenna array

There is growing interest in the use of additive manufacturing for the fabrication of RF devices due to fast prototyping capabilities and the use of less material as opposed to traditional fabrication techniques. In addition to the previously mentioned advantages, the aerosol jet printing method in particular allows for the conformal printing of RF components. This work models the effect of the bend radius on the return loss and radiation pattern of a dual-band (28 GHz and 39 GHz) mm wave patch antenna array design that will be aerosol jet printed. The antenna is modeled on a 5-mil thick flexible substrate (PET) and the simulation is run from 27 GHz to 40 GHz using HFSS. The return loss and radiation pattern results of the antenna are compared for various bend radii (0.25 in to 2 in) of the conformal surface the antenna is to be printed upon. Simulation results show a maximum frequency deviation of about 400 MHz on the return loss for the low (28 GHz) frequency band of the antenna when it is bent from a bend radius of 0 in to 2 in.