Transmit-array Lens Research Articles

Multi-beam high gain steerable transmitarray lens for satellite communication and 5G mm-Wave systems

This paper presents the design of a high gain multi-beam transmitarray antenna. Designed antenna is capable of independently steering multiple beams in the azimuth and elevation plane by the two dimensional displacement of feed radiators placed in front of the passive meta-surface. The meta-surface acts as an electromagnetic lens. Unit cell of the meta-surface consists of three layers of Rogers 5880 substrate and four layers of etched copper. Unit cell is designed such that the phase of unit cell transmission coefficient is varied from 0° to 360° by changing length of the etched copper pattern. As a proof of concept, meta-surface is designed by using uni-focal phase distribution. Multi-beam steering of 0° to 360° in azimuth plane and 0° to 40° in elevation plane has been achieved. Measured antenna peak gain is 34.2 dBi at 30 GHz. Later on, scan loss was optimized by synthesizing a meta-surface with bi-focal phase distribution. This is a mission enabling technology as the antenna supports seamless hand-off between satellites by forming multiple high gain independently steerable beams. Comparable antennas to the date are low gain, bulky, support limited number of beams, and have limited field of view. To the best of the author’s knowledge, it is first time that high gain multi-beam antenna has been demonstrated by using a passive bi-focal meta-surface for continuous beam steering. Due to absence of active components the designed antenna is low cost and robust. Moreover, the substrate is selected such that the antenna can withstand harsh deep space environment and it can be folded for easy deployment. Due to potentially low fabrication cost and ability to support multiple beams, the proposed antenna is a good candidate for next generation satellite communication and mm-Wave 5G systems.

A Subwavelength Transmit-Array Lens Element Combining Functions of Phase Modulation and Polarization Conversion

Advanced applications require transmit-array lenses featuring low profiles, covering 360° phase modulation, and, potentially, polarization conversion. Subwavelength metamaterial elements with multilayers manipulate electromagnetic waves with predesigned phase shifts, resulting in the transmit-array lens’s low profile and light weight. Conventional designs separate the transmit-array lens and polarization converter with two functional devices and suffer from high profiles and complicated mechanical assembly. In order to resolve these issues, a subwavelength lens element combining the functions of phase modulation and polarization conversion is proposed. The metamaterial lens element consists of phase modulation, linear-circular polarization conversion modules, and a metallic via structure electrically connecting these two modules. The multifunctional lens element modulates the transmitted phase with a three-bit phase shift and operates in the frequency range from 24.5 to 27 GHz, with less than −10 dB reflection coefficient, 1 dB transmission loss, and a 2.5 dB axial ratio. A transmit-array lens antenna with the proposed element is implemented to validate the abilities of beam focus and polarization conversion. The gain of the lens antenna reaches 26.3 dBi, with a 3 dB beamwidth of 6.7° and −18 dB sidelobe level, and the axial ratio of the converted circular polarization is below 1 dB. The aperture efficiency of the antenna is 45.2%.

Evaluation of Transmit-Array Lens Antenna for Deep-Seated Hyperthermia Tumor Treatment

A transmit-array lens antenna is proposed with a view to optimally treat patients with tumors deep inside their bodies. The proposed antenna produces a destructive interference of the electric field that can reduce the heat generated at the skin by the heat-nulling technique. Simultaneously, it concentrates microwave energy on the deep-seated tumor. It is possible to heat an area of 114 mm2 at a 50 mm depth below the skin without damage to normal cells. The specific absorption rate (SAR) at a depth of 50 mm corresponds to 50% of the maximum SAR induced in the human body. These results show that the proposed transmit-array lens antenna is suitable for treating tumors located deep inside the body, such as kidney cancer.

Low‐profile transmitarray lens antenna of X‐band with one layer of substrate and metallic vias

A low-profile transmitarray lens design is presented at X-band, which is composed of only one layer of substrate with thickness of 0.13 free-space wavelengths. The transmitted unit cell utilises structure of two metallic layers and four via holes, broadening the transmitted phase shift range to more than 310° while transmission magnitude is within −3 dB under normal incidence. A prototype of the transmitarray lens with aperture size of 280 mm is designed, simulated and measured. Measurement and simulation results agree well with each other and gain of 23.9 dBi is obtained at 10 GHz; the proposed low-profile transmitarray lens antenna could be applied to practical X-band radar systems with low cost and convenience.

One-Dimensional Beam Scanning Transmitarray Lens Antenna Fed by Microstrip Linear Array

This paper proposed a one-dimensional beam scanning transmitarray lens antenna fed by a microstrip linear array antenna which owns a wide pattern in the plane orthogonal to the array axis and a narrow pattern in the plane that includes the array axis. The design principle of transmitarray lens aims to modulate a fan beam into a pencil beam by compensating phase shift of the linear array on the plane orthogonal to the array axis at X band. First, the Rotman lens feed network is used to implement nearly ±40° one-dimensional beam scanning for the linear array with 1 × 8 microstrip antenna elements. Then, a lowprofile transmitted element with only one-layer of the substrate is utilized to design the new transmitarray lens, which can reduce fabrication expense and difficulties. After adding the transmitarray lens, maximum gain increments of 7.81 and 7.65 dB in simulation and measurement can be obtained in quasi-boresight directions, and gain increment could be obtained within ±25° beam scanning range. Besides, the fan beams of the original linear array are smoothly transformed into pencil beams.

An Ultra-Thin 2-bit Near-Field Transmitarray Lens

A novel ultrathin near-field (NF) 2-bit 24 $\times$ 24-element transmitarray lens working at X -band is presented in this letter. The aim of this antenna is to focus in a point located in the NF without using any complex feeding network. In order to obtain a planar lens with a very low profile, a 2-bit-design approach is used to diminish the number of layers used in the structure. The simulations have been done using a model based on the concept that the NF of an array can be calculated as the sum of the far-field contributions of every single one of its elements. These are considered as plane apertures over which the tangential electric field is constant. In order to validate the results of this model, they are compared to both those obtained with a full-wave commercial software and those from measurements. Thus, an NF antenna is manufactured and measured showing the measurements’ good concordance with the results of the model.

Design of Noninvasive Hyperthermia System Using Transmit-Array Lens Antenna Configuration

A transmit-array (TA)-lens-mounted hyperthermia applicator is proposed to enhance the therapeutic suitability for treatments of superficial tumors. The hyperthermia applicator, which consists of the external radiator, TA lens, and water-bolus, is designed to provide pain-free treatment of tumors. The external radiator is designed to support a uniform electromagnetic (EM) field distribution on the lens surface, and the configuration of the TA lens leads to a summation of EM energies by compensating for the phase delays for different path lengths from each elementary cell of the TA lens to the desired treatment area, which allows for optimal heat deposition at the therapeutic target. The proposed hyperthermia applicator is configured with two lenses for thermal focusing and spreading experiments. In this study, the definition of the effective treatment area (ETA) was used to evaluate thermal performance of the hyperthermia system. The calculated ETAs in two experiments (thermal focusing and spreading configurations) showed a decrease of 49% and an increase of 281%, respectively, as compared to lens-free operation.

A Simple Model for Analyzing Transmitarray Lenses

i»?A new model for characterizing a complex system formed by a feeding horn and a transmitarray lens is presented in this paper. This model characterizes the spillover radiation and is capable of analyzing its effect on the radiation pattern. Both the contribution of the lens and the spillover radiation are modeled as planar arrays. The proposed model shows good agreement with the results obtained in simulations using a commercial full-wave software. In addition, some features, such as the characterization of the feeding element, are included in this model, in order to improve its accuracy. Finally, the limits of applicability are also discussed throughout this paper. Thus, it is possible to set up the boundaries, in terms of F/D ratio and number of elements, within which the model is reliable.

Design of High-Directivity Compact-Size Conical Horn Lens Antenna

The design of lightweight, compact-size, and high-directivity conical horn lens antenna that covers both 71-76 and 81-86 GHz bands is presented in this letter. The conventional conical moderate-gain horn antenna is integrated with a planar inhomogeneous dielectric flat transmit-array lens having diameter of 35 mm and thickness of 6.35 mm by covering its aperture. The transmit-array lens is designed based on the perforating dielectric technique that is based on the drilling of numerous holes of variable diameters through a dielectric host material. The unit cell size is about λ0/2, which allows for easier fabrication. The proposed lens consists of eight concentric zones of same width of 2.32 mm and sharing the same host dielectric material. A directivity of 26.4 dBi, 9 dBi improvement, sidelobe level (SLL) of -15.7 dB at 74 GHz and directivity of 27 dBi, 9.9 dBi improvement, and SLL of -18.4 dB at 86 GHz were achieved. The proposed horn antenna is 44.46% shorter than the conventional horn antenna producing the same directivity, where the horn antenna length reduction is a result of using the proposed transmit-array lens.

Passive planar transmit‐array microstrip lens for microwave purpose

AbstractA complete transmit‐array lens device at 12 GHz, for microwave purpose, is offered in this manuscript.In this document, an overview of the functioning of this kind of devices is given and the proposed transmit‐array lens is thoroughly studied, with architecture discussion and selection, as well as the design, manufacturing, and validation of all the constituting elements of the lens (radiating elements, transmission circuits, and transitions). Eventually, a complete prototype of transmit‐array lens is assembled and radiation pattern measurements in anechoic chamber, as well as gain and directivity values, are offered. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:940–947, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25078

Ku band transmitarray lens for microwave applications

In this document a microstrip constrained lens device for Ku band, for microwave purpose, is presented. This paper offers an overview of artificial lens-type devices and the proposed transmitarray lens is thoroughly studied in terms of design and manufacturing, with architecture discussion and selection, along with the design, manufacturing and validation of all the forming components of the transmitarray (transmission circuits, radiating elements, etc.). Each element is properly characterized and assembled properly in the complete transmitarray prototype. Eventually, radiation pattern measurements as well as gain and directivity values, are provided to show the proper behaviour of the proposed transmitarray lens.