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W.H. Syed
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Connected-Slot Array with Artificial Dielectrics
A 6 to 15 GHz Dual-Pol Wide-Scan Prototype
In this work we report on the design, manufacturing and testing of a dual-polarized array of connected slots radiating in the presence of an artificial dielectric superstrate. The prototype array consists of 512 elements, i.e. 16×16 connected slots for each of the two polarizations. The antenna array is realized with a single multi-layer printed circuit board (PCB), which represents an advantage in terms of cost and complexity with respect to the typical configuration based on multiple vertically arranged PCBs. The performance is investigated in terms of simulated and measured matching characteristics and radiation patterns. The proposed structure achieves active voltage standing wave ratio (VSWR) lower than 3.1 over about an octave bandwidth (6 to 15 GHz), within a wide scan range (±60° in the H-plane and ±80° in the E-plane).
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In this work we report on the design, manufacturing and testing of a dual-polarized array of connected slots radiating in the presence of an artificial dielectric superstrate. The prototype array consists of 512 elements, i.e. 16×16 connected slots for each of the two polarizations. The antenna array is realized with a single multi-layer printed circuit board (PCB), which represents an advantage in terms of cost and complexity with respect to the typical configuration based on multiple vertically arranged PCBs. The performance is investigated in terms of simulated and measured matching characteristics and radiation patterns. The proposed structure achieves active voltage standing wave ratio (VSWR) lower than 3.1 over about an octave bandwidth (6 to 15 GHz), within a wide scan range (±60° in the H-plane and ±80° in the E-plane).
In this work we report on the design, manufacturing and testing of a dual-polarized array of connected slots radiating in the presence of an artificial dielectric superstrate. The prototype array consists of 512 elements, i.e. 16×16 connected slots for each of the two polarizations. The antenna array is realized with a single multi-layer printed circuit board (PCB) and thus is low-cost compared to the typical configuration based on multiple vertically arranged PCBs. The performance is investigated in terms of simulated and measured matching characteristics and radiation patterns. The proposed structure achieves active voltage standing wave ratio (VSWR) lower than 3.1 over about an octave bandwidth (6 to 15 GHz), within a wide scan range (±60° in the H-plane and ±80° in the E-plane).
...
In this work we report on the design, manufacturing and testing of a dual-polarized array of connected slots radiating in the presence of an artificial dielectric superstrate. The prototype array consists of 512 elements, i.e. 16×16 connected slots for each of the two polarizations. The antenna array is realized with a single multi-layer printed circuit board (PCB) and thus is low-cost compared to the typical configuration based on multiple vertically arranged PCBs. The performance is investigated in terms of simulated and measured matching characteristics and radiation patterns. The proposed structure achieves active voltage standing wave ratio (VSWR) lower than 3.1 over about an octave bandwidth (6 to 15 GHz), within a wide scan range (±60° in the H-plane and ±80° in the E-plane).
At millimeter and sub-millimeter wave frequencies, electronic circuits and antennas are often located on the same semiconductor chip to facilitate their interconnection. However, on-chip antennas are characterized by very poor radiation efficiency and extremely narrow bandwidth. This is because they are situated at small electrical distance from a ground plane that shields the antenna from the lossy bulk. High-permittivity superstrates can be located above the antennas to improve the impedance properties, but they support the propagation of surface waves which reduce the efficiency. Here we propose the use of artificial dielectric (AD) superstrates above the antennas to improve significantly their performance. Because of their anisotropy, AD slabs do not support surface waves, thus enabling high-efficiency designs. To clarify the concept, we investigate the properties of a simple dipole antenna on chip in terms of impedance and efficiency. Full-wave simulations predict efficiency up to 87% with the presence of the AD.
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At millimeter and sub-millimeter wave frequencies, electronic circuits and antennas are often located on the same semiconductor chip to facilitate their interconnection. However, on-chip antennas are characterized by very poor radiation efficiency and extremely narrow bandwidth. This is because they are situated at small electrical distance from a ground plane that shields the antenna from the lossy bulk. High-permittivity superstrates can be located above the antennas to improve the impedance properties, but they support the propagation of surface waves which reduce the efficiency. Here we propose the use of artificial dielectric (AD) superstrates above the antennas to improve significantly their performance. Because of their anisotropy, AD slabs do not support surface waves, thus enabling high-efficiency designs. To clarify the concept, we investigate the properties of a simple dipole antenna on chip in terms of impedance and efficiency. Full-wave simulations predict efficiency up to 87% with the presence of the AD.
On-chip antennas operating in the THz frequency range are characterized by narrow bandwidth and poor radiation efficiency. This is because they are electrically very close to the ground plane that is used to shield the antenna from the lossy substrate. In this work we propose a novel approach to increase the efficiency and the bandwidth of antennas integrated on chip, by exploiting and combining the two concepts of connected arrays and artificial dielectric layers.
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On-chip antennas operating in the THz frequency range are characterized by narrow bandwidth and poor radiation efficiency. This is because they are electrically very close to the ground plane that is used to shield the antenna from the lossy substrate. In this work we propose a novel approach to increase the efficiency and the bandwidth of antennas integrated on chip, by exploiting and combining the two concepts of connected arrays and artificial dielectric layers.
We present an approach to realize wideband and low-loss antennas and antenna arrays on chip. The radiators are loaded with an artificial dielectric superstrate to improve the bandwidth and the overall efficiency. An example of design is proposed, consisting of an array of connected-dipole elements operating in a frequency band around 300 GHz. The antenna elements are located in the close proximity of a metal plane that functions as a shield from the lossy silicon substrate. Although the distance from the ground plane is only one fortieth of the wavelength, a bandwidth of 15% is achieved by loading the antenna with an artificial dielectric superstrate with high equivalent permittivity. The artificial dielectric does not support surface waves as a real dielectric, due to its anisotropic property. Consequently, remarkably high efficiency can be achieved with this radiation concept (>60% from simulation).
...
We present an approach to realize wideband and low-loss antennas and antenna arrays on chip. The radiators are loaded with an artificial dielectric superstrate to improve the bandwidth and the overall efficiency. An example of design is proposed, consisting of an array of connected-dipole elements operating in a frequency band around 300 GHz. The antenna elements are located in the close proximity of a metal plane that functions as a shield from the lossy silicon substrate. Although the distance from the ground plane is only one fortieth of the wavelength, a bandwidth of 15% is achieved by loading the antenna with an artificial dielectric superstrate with high equivalent permittivity. The artificial dielectric does not support surface waves as a real dielectric, due to its anisotropic property. Consequently, remarkably high efficiency can be achieved with this radiation concept (>60% from simulation).
In this paper, we present an analysis of the edge effects in wideband connected arrays of slots and dipoles. Due to the strong mutual coupling between the elements, these arrays can support the propagation of guided waves along their surface. Such waves arise from the edges of the finite array and can be
especially detrimental to the performance, since they can travel within the array without geometrical spreading. In this paper, we introduce Green’s function-based equivalent transmission line models to describe the propagation of the guided waves. The elements’ active impedances are represented as periodic loads
on these transmission lines. The equivalent models can be used as a simple and convenient tool to control and minimize the edge effects. Finite array simulations of relevant array structures are discussed. The evidence is that the active impedance and the interelement capacitance can be tuned to attenuate and reflect
the edge-born waves. ...
especially detrimental to the performance, since they can travel within the array without geometrical spreading. In this paper, we introduce Green’s function-based equivalent transmission line models to describe the propagation of the guided waves. The elements’ active impedances are represented as periodic loads
on these transmission lines. The equivalent models can be used as a simple and convenient tool to control and minimize the edge effects. Finite array simulations of relevant array structures are discussed. The evidence is that the active impedance and the interelement capacitance can be tuned to attenuate and reflect
the edge-born waves. ...
In this paper, we present an analysis of the edge effects in wideband connected arrays of slots and dipoles. Due to the strong mutual coupling between the elements, these arrays can support the propagation of guided waves along their surface. Such waves arise from the edges of the finite array and can be
especially detrimental to the performance, since they can travel within the array without geometrical spreading. In this paper, we introduce Green’s function-based equivalent transmission line models to describe the propagation of the guided waves. The elements’ active impedances are represented as periodic loads
on these transmission lines. The equivalent models can be used as a simple and convenient tool to control and minimize the edge effects. Finite array simulations of relevant array structures are discussed. The evidence is that the active impedance and the interelement capacitance can be tuned to attenuate and reflect
the edge-born waves.
especially detrimental to the performance, since they can travel within the array without geometrical spreading. In this paper, we introduce Green’s function-based equivalent transmission line models to describe the propagation of the guided waves. The elements’ active impedances are represented as periodic loads
on these transmission lines. The equivalent models can be used as a simple and convenient tool to control and minimize the edge effects. Finite array simulations of relevant array structures are discussed. The evidence is that the active impedance and the interelement capacitance can be tuned to attenuate and reflect
the edge-born waves.
We propose a radiation concept to realize phased arrays with wideband and wide-scanning performance. The array is based on connected-slot elements that radiate in the presence of artificial dielectric superstrates. The array can be implemented with a single multi-layer printed circuit board. Artificial dielectrics are used in place of real dielectrics to minimize the losses due to surface waves and avoid the occurrence of scan blindness over a wide scan range. The achievable bandwidth depends on the number of layers composing the artificial dielectric. A design example is shown that achieves a bandwidth (VSWR<;2.5) of about 5:1 when scanning up to 50° in all azimuth planes. Both single- and dual-polarization designs can be implemented.
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We propose a radiation concept to realize phased arrays with wideband and wide-scanning performance. The array is based on connected-slot elements that radiate in the presence of artificial dielectric superstrates. The array can be implemented with a single multi-layer printed circuit board. Artificial dielectrics are used in place of real dielectrics to minimize the losses due to surface waves and avoid the occurrence of scan blindness over a wide scan range. The achievable bandwidth depends on the number of layers composing the artificial dielectric. A design example is shown that achieves a bandwidth (VSWR<;2.5) of about 5:1 when scanning up to 50° in all azimuth planes. Both single- and dual-polarization designs can be implemented.
Microwave broadband wide-scan antenna arrays are typically implemented resorting to vertical arrangements of printed circuit boards (PCBs). Here, we propose a planar solution realized with a single multi-layer PCB, with consequent reduction in cost and complexity of the array. It consists of an array of connected slots backed by a metallic reflector and loaded with superstrates. Artificial dielectric layers (ADLs) are used in place of real dielectrics to realize the superstrates, as they are characterized by very low surface-wave losses. For the unit-cell design, we developed an analysis tool based on closed-form expressions and thus requiring minimal computational resources. Finite-array simulations are also performed by generalizing the analysis method to account for the truncation effects. The presence of the ADL superstrate allows reducing the distance between the array plane and the backing reflector while maintaining good matching performance. A realistic feed structure is also proposed, which consists of a microstrip line connected to a coaxial feed. Such a solution does not require balanced-to-unbalanced transitions, which often limit the achievable bandwidth. The proposed structure achieves in simulations more than an octave bandwidth (6.5–14.5 GHz), within a scanning range of ±50 degrees in all azimuth planes.
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Microwave broadband wide-scan antenna arrays are typically implemented resorting to vertical arrangements of printed circuit boards (PCBs). Here, we propose a planar solution realized with a single multi-layer PCB, with consequent reduction in cost and complexity of the array. It consists of an array of connected slots backed by a metallic reflector and loaded with superstrates. Artificial dielectric layers (ADLs) are used in place of real dielectrics to realize the superstrates, as they are characterized by very low surface-wave losses. For the unit-cell design, we developed an analysis tool based on closed-form expressions and thus requiring minimal computational resources. Finite-array simulations are also performed by generalizing the analysis method to account for the truncation effects. The presence of the ADL superstrate allows reducing the distance between the array plane and the backing reflector while maintaining good matching performance. A realistic feed structure is also proposed, which consists of a microstrip line connected to a coaxial feed. Such a solution does not require balanced-to-unbalanced transitions, which often limit the achievable bandwidth. The proposed structure achieves in simulations more than an octave bandwidth (6.5–14.5 GHz), within a scanning range of ±50 degrees in all azimuth planes.
In this paper, we present an overview of our recent works on artificial dielectric layers (ADLs), used to enhance the radiation efficiency of planar printed antennas and arrays. The artificial material is realized by introducing planar sub-resonant metallic inclusions in a host material. This allows to enhance the permittivity of the host medium, which is characterized by high anisotropy. An analytical method has been developed to model the ADLs, valid for arbitrary number of layers and generic illumination. After a general description of this method, two design examples are presented. The first utilizes a single ADL slab as a superstrate of an on-chip double slot antenna operating at 300 GHz. Simulated and measured results show an improvement of the antenna gain and overall efficiency of about 2 dB. The second example exploits the use of the ADLs for the design of wideband, wide-scan planar phased arrays. A connected-slot array is loaded with an ADL superstate, to achieve wide-scan capability, up to 50 degrees in all azimuth planes, over an octave bandwidth.
...
In this paper, we present an overview of our recent works on artificial dielectric layers (ADLs), used to enhance the radiation efficiency of planar printed antennas and arrays. The artificial material is realized by introducing planar sub-resonant metallic inclusions in a host material. This allows to enhance the permittivity of the host medium, which is characterized by high anisotropy. An analytical method has been developed to model the ADLs, valid for arbitrary number of layers and generic illumination. After a general description of this method, two design examples are presented. The first utilizes a single ADL slab as a superstrate of an on-chip double slot antenna operating at 300 GHz. Simulated and measured results show an improvement of the antenna gain and overall efficiency of about 2 dB. The second example exploits the use of the ADLs for the design of wideband, wide-scan planar phased arrays. A connected-slot array is loaded with an ADL superstate, to achieve wide-scan capability, up to 50 degrees in all azimuth planes, over an octave bandwidth.
Journal article
(2015)
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Waqas H. Syed, Giuseppe Fiorentino, Daniele Cavallo, Marco Spirito, Pasqualina M. Sarro, Andrea Neto
In this paper, we demonstrate, at 300 GHz and with integrated technology, the effectiveness of artificial dielectric layers to enhance the front-to-back ratio of printed antennas. This concept was previously proposed at microwave frequencies and using printed circuit board technology. The artificial material is now realized by introducing non-resonant metallic inclusions in a silicon dioxide host material. This allows to enhance the permittivity of the host medium and renders it anisotropic. By loading an electrically
thin dielectric with these metallic inclusions, an engineered slab with effectively quarter wavelength thickness has been realized.
Despite the large effective height and density of the artificial dielectric, the surface wave efficiency of the antenna is 99%. This
is entirely due to the anisotropic properties of the material. A prototype antenna was built using an in-house CMOS back-end compatible integrated circuits (IC) process. Measured results from the antenna are presented and show a good agreement with the expected results. ...
thin dielectric with these metallic inclusions, an engineered slab with effectively quarter wavelength thickness has been realized.
Despite the large effective height and density of the artificial dielectric, the surface wave efficiency of the antenna is 99%. This
is entirely due to the anisotropic properties of the material. A prototype antenna was built using an in-house CMOS back-end compatible integrated circuits (IC) process. Measured results from the antenna are presented and show a good agreement with the expected results. ...
In this paper, we demonstrate, at 300 GHz and with integrated technology, the effectiveness of artificial dielectric layers to enhance the front-to-back ratio of printed antennas. This concept was previously proposed at microwave frequencies and using printed circuit board technology. The artificial material is now realized by introducing non-resonant metallic inclusions in a silicon dioxide host material. This allows to enhance the permittivity of the host medium and renders it anisotropic. By loading an electrically
thin dielectric with these metallic inclusions, an engineered slab with effectively quarter wavelength thickness has been realized.
Despite the large effective height and density of the artificial dielectric, the surface wave efficiency of the antenna is 99%. This
is entirely due to the anisotropic properties of the material. A prototype antenna was built using an in-house CMOS back-end compatible integrated circuits (IC) process. Measured results from the antenna are presented and show a good agreement with the expected results.
thin dielectric with these metallic inclusions, an engineered slab with effectively quarter wavelength thickness has been realized.
Despite the large effective height and density of the artificial dielectric, the surface wave efficiency of the antenna is 99%. This
is entirely due to the anisotropic properties of the material. A prototype antenna was built using an in-house CMOS back-end compatible integrated circuits (IC) process. Measured results from the antenna are presented and show a good agreement with the expected results.
We present an analytical method to model artificial dielectric layers (ADLs) of finite height. Starting from the closed-form solution for the scattering from a single layer under plane wave illumination, the formulation is extended to the multi-layer case, by including the higher-order interaction between parallel layers in analytical form. The method can be used to describe the radiation of a source located in the close proximity of the ADL. Experimental data obtained from a prototype demonstrator are presented and show a good agreement with the results of the theoretical analysis.
...
We present an analytical method to model artificial dielectric layers (ADLs) of finite height. Starting from the closed-form solution for the scattering from a single layer under plane wave illumination, the formulation is extended to the multi-layer case, by including the higher-order interaction between parallel layers in analytical form. The method can be used to describe the radiation of a source located in the close proximity of the ADL. Experimental data obtained from a prototype demonstrator are presented and show a good agreement with the results of the theoretical analysis.
A Planar Wideband Wide-Scan Phased Array
Connected Array Loaded with Artificial Dielectric Layers
Conference paper
(2015)
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Daniele Cavallo, Waqas H. Syed, Harshitha Thippur Shivamurthy, Andrea Neto
We present a novel concept for wideband, wide-scan phased array applications. The array is composed by connected-slot elements loaded with artificial dielectric superstrates. The proposed solution consists of a single multi-layer planar printed circuit board (PCB) and does not require the typically employed vertical arrangement of multiple PCBs. This offers advantages in terms of complexity of the assembly and cost of the array. We developed an analytical method for the prediction of the array performance, in terms of active input impedance. This method allows to estimate the relevant parameters of the array with a negligible computational cost. A design example with a bandwidth exceeding one octave (VSWR<2 from 6.5 to 14.3 GHz) and scanning up to 50 degrees for all azimuth planes is presented.
...
We present a novel concept for wideband, wide-scan phased array applications. The array is composed by connected-slot elements loaded with artificial dielectric superstrates. The proposed solution consists of a single multi-layer planar printed circuit board (PCB) and does not require the typically employed vertical arrangement of multiple PCBs. This offers advantages in terms of complexity of the assembly and cost of the array. We developed an analytical method for the prediction of the array performance, in terms of active input impedance. This method allows to estimate the relevant parameters of the array with a negligible computational cost. A design example with a bandwidth exceeding one octave (VSWR<2 from 6.5 to 14.3 GHz) and scanning up to 50 degrees for all azimuth planes is presented.
We present an analytical formulation to describe the plane-wave propagation through artificial dielectric layers (ADLs) of finite thickness. The formulation is based on a spectral domain approach derived for connected arrays. An analytical circuit model based on this approach is reported, which makes use of lumped loads to represent the reactance associated with each layer and the coupling between adjacent layers. Furthermore, a zero order mode transmission lines is used to characterize the transmission and the reflection of an incident plane wave. The circuital representation is first derived for an infinite number of layers and then extended to treat the case of finite height ADL slabs.
...
We present an analytical formulation to describe the plane-wave propagation through artificial dielectric layers (ADLs) of finite thickness. The formulation is based on a spectral domain approach derived for connected arrays. An analytical circuit model based on this approach is reported, which makes use of lumped loads to represent the reactance associated with each layer and the coupling between adjacent layers. Furthermore, a zero order mode transmission lines is used to characterize the transmission and the reflection of an incident plane wave. The circuital representation is first derived for an infinite number of layers and then extended to treat the case of finite height ADL slabs.