Uniplanar Compact Photonic Bandgap Research Articles

Millimeter-Wave Frequency-Reconfigurable Metasurface Antenna Based on Vanadium Dioxide Films

A novel frequency-reconfigurable method using vanadium dioxide (VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) is proposed. VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is one kind of phase change material (PCM) which can be electrically switched between the states of insulator and metal. By integrating the VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> film into a uniplanar compact photonic-bandgap (UC-PBG) structure, a frequency-reconfigurable metasurface (FRMS) structure with frequency ratio of 1.78 is constructed accordingly. Moreover, the active VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based FRMS is used as radiation element to design a high-gain millimeter-wave frequency-reconfigurable metasurface antenna (FRMSA), which is excited by a stepped waveguide through two slots of different lengths. In order to electrically activate the VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> films of the antenna, a simple dc bias co-planarly localized with the FRMS is well designed. Benefiting from the convenient connection of the UC-PBG, only simple connection with two sides of the antenna is required for the dc bias, thus causing little impact on radiation due to far from the radiation region. One prototype is fabricated and measured for demonstration. When the VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> film is activated to insulating state, the measured results show that the proposed FRMSA can operate in 23.25-24.3 GHz with the maximum gain of ~8.7 dBi, while it can work in 37-39.8 GHz with a peak gain of ~7.6 dBi when driven to metallic state. The ratio of two frequencies is about 1:1.61. Compared with other reported VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based antennas, the proposed antenna exhibits a larger frequency ratio and higher gain in millimeter-wave bands.

Improving the performance of a patch antenna array by using photonic bandgap structures at X-band

A proposed three-layered patch antenna array combined with Uniplanar Compact Photonic Bandgap structures (UC-PBG) is presented to avoid non-desired radiations from the feeding structure and to mitigate the surface propagation modes, increasing the radiation efficiency, and reducing the parasitic lobes. The array is fed by electromagnetic proximity, implemented by a stripline network below the radiators. The array is designed to operate at of 10 GHz and is surrounded by UC-PBG structures. This configuration also helps to increase the bandwidth by keeping the electric field and the surface current stable around the radiators, reducing the variations of the impedance on a wider bandwidth. Also, the UC-PBG structures attenuate the surface propagation modes, lowering the parasitic lobes by almost 7 dB and reaching measured radiation efficiency higher than 80%. The patch array gets an operational bandwidth of 2.5 GHz, with a measured gain of 24 dB. The fractional bandwidth is 25%.

Three‐layered circular patch antennas array with UC‐PBG for wider bandwidth and surface wave propagation mode attenuation at X‐band

AbstractIn this work, a three‐layered antenna array complemented with Uniplanar Compact Photonic‐Bandgap (UP‐PBG) structure is presented, for applications in the X‐band. The proposed array consists of circular patch radiator operating at 10 GHz, where the element is surrounded by UC‐PBG unit cells in order to improve the performance of the antenna. By combining the radiator and the UC‐PBG cells, the directivity, gain and polarization are kept, while the parasitic lobes are reduced 50% their magnitude. The bandwidth augments 44% compared to a conventional array, and a diminution of the surface propagation mode is obtained, increasing the radiation efficiency.

Prof. Itoh's Contributions to Antennas [Awards

Prof. Tatsuo Itoh is a preeminent researcher, mentor, and educator, whose efforts have influenced many in the field of electromagnetics and microwave engineering. Although Prof. Itoh may be best known for numerical techniques and periodic/metamaterial structures, he has also left his mark in the antenna community. Some of Prof. Itoh's antenna-related works include antennas and arrays that integrate active components such as push–pull power amplifiers and coupled oscillators to enable efficient radiation, spatial power combining, and beamsteering; broadband planar quasi-Yagi antennas that produce highly directive end-fire radiation [S34]–[S35]; uniplanar-compact photonic bandgap (PBG)-enhanced high-gain antennas; retrodirective arrays that can reradiate an incoming signal toward the source without a priori knowledge of the arrival direction; and metamaterial antennas that support unconventional radiation characteristics such as broad spatial-angle frequency scanning and negative/zeroth-order mode radiations.

Dual‐band, dual‐polarised metallic slot transmitarray antenna

A metallic, dual-band, dual polarised slot-based transmitarray antenna is presented. The antenna consists of three thin metallic layers do not use any dielectric substrates, with air gaps in between the layers. The unit cell uses interleaved orthogonal slots, as well as crossed-dipole slot and uniplanar compact photonic bandgap slot elements to provide the lower and upper frequency band resonators, respectively. The frequency separation between the two resonances can be adjusted from closely spaced to far from each other. The antenna provides dual linear polarisation and circular polarisation with the use of the appropriate feed. The fabricated transmitarray antenna provides two independent frequency bands with a band ratio of 1.13 and low mutual coupling. The measurement of a 14 × 14 element transmitarray antenna at 11 GHz shows a maximum gain of 23.74 dB with -1 dB gain bandwidth of 6.8% and aperture efficiency of 38%; at 12.5 GHz, a maximum gain of 24.45 dB is obtained with -1 dB gain bandwidth of 5.4% and aperture efficiency of 34.6%. The antenna is simulated by using the CST software; the ADS package is used for equivalent circuit simulation.

Dispersion Analysis and Design of Planar Electromagnetic Bandgap Ground Plane for Broadband Common-Mode Suppression

Planar electromagnetic bandgap (EBG) structure designed for broadband common-mode suppression is proposed. A uniplanar compact photonic-bandgap (UC-PBG) structure with periodic center slots is etched on the ground plane to obtain broadband common mode suppression while minimally disturbing the differential signal within the designed bandwidth. Dispersion analysis has been conducted for both common (even) and differential (odd) mode signals. Good signal integrity is observed in both simulated and measured results. The fractional bandwidth of the proposed EBG ground plane is around 80 % with common-mode suppression below -15 dB. The proposed EBG ground planes may be applicable for systems requiring low- cost and simple solutions in designing high-speed differential interlinks operating above 5 Gbps.

Parametric Study of UC-PBG Structure in Terms of Simultaneous AMC and EBG Properties and its Applications in Proximity-coupled Fractal Patch Antenna

In this paper, a parametric study of conventional Uniplanar Compact Photonic Band Gap (UC-PBG) structures, with different dimensions, is investigated. The studied structure operates as an Artificial Magnetic Conductor (AMC) in which the performance is mainly characterized by the resonant frequency and bandwidth. Simulation and numerical analysis have been carried out using CST Microwave Studio software, which is based on Finite Difference Time Domain (FDTD), and Ansoft HFSS which is based on Finite Element Method (FEM). Results show that different dimensions affect the AMC\'s performance. The increase in the length and width of the UC-PBG slot will result in lower resonant frequencies and bandwidth degradation, while the frequency band position and the bandwidth will increase when the branch width have been increased. Furthermore, a prototype of a microstrip line proximity-fed to a fractal patch antenna on a UC-PBG substrate is designed and simulated. Computed results show that the antenna mounted on the UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a grounded dielectric slab with same the same characteristics, due to in-phase reflection phase of UC-PBG structure. Compared with the reference antenna at 7.2 GHz, the back lobe is reduced by 7.86 dB in E plane and 7.68 dB in H plane. Cross-polarization level remains below -10 dB in both E and H planes.

NUMERICAL ANALYSIS OF CONFORMAL UC-PBG STRUCTURES

In this paper, the performance of conventional Uniplanar Compact Photonic Band Gap (UC-PBG) structures is investigated under difierent bending extents. The structure under study is operated as an Artiflcial Magnetic Conductor (AMC) in which performance is mainly characterized by its resonant frequency and bandwidth. Modelling and numerical analysis have been carried out using CST Microwave Studio simulation software which is based on Finite Integration Technique (FIT). Results show that difierent bending extents afiect the AMC's performance which is specifled by a shift to higher resonant frequencies and bandwidth degradation when the degree of bending is increased. Furthermore, we point out some important simulation tips to avoid inaccurate and/or invalid results. This type of study is important to evaluate the performance of such structures for conformal applications. To the best of the authors' knowledge, such type of systematic study is being reported for the flrst time.

THEORY OF GAIN ENHANCEMENT OF UC-PBG ANTENNA STRUCTURES WITHOUT INVOKING MAXWELL'S EQUATIONS: AN ARRAY SIGNAL PROCESSING APPROACH

In this paper, a novel and computationally e-cient algorithm which combines Array Signal Processing (ASP) approach with Fourier Optics (FO) is developed in the realm of gain enhancement achieved by placing Uniplanar Compact-Photonic Band Gap (UC- PBG) structures on top of microstrip antennas. The proposed scheme applies FO to the well-known sampling theorem borrowed from Digital Signal Processing (DSP) analysis in the framework of ASP approach which we refer to as the FDA algorithm. The FDA algorithm is suitable for lossless UC-PBG structures with 1- D, 2-D and 3-D lattice of canonical geometrical apertures, such as circular, octagonal, hexagonal, and square. In order to validate the proposed approach, two difierent UC-PBG structures of octagonal and circular apertures are considered at 2.6GHz. The UC-PBG structures under consideration consist of two layers positioned above a microstrip antenna; each layer is an array of 9 £ 9 apertures separated by half of the focal length distance of the lens in the near- fleld of the microstrip antenna. The performance of the microstrip antenna with and without the UC-PBG is reported using numerical simulations performed using CST Microwave Studio (CST MWS) based on the Finite Integration Technique (FIT). The radiation patterns and directivity of the microstrip antenna based on UC- PBG structures are evaluated using the proposed FDA algorithm and

Numerical simulation of a UC-PBG lens for gain enhancement of microstrip antennas

Because of their versatility and ease of fabrication, Uniplanar Compact–Photonic Band Gap (UC–PBG) structures have been recently applied to microstrip antenna design. However, when the PBG structure is embodied on the ground plane of a conventional microstrip antenna, the resulting configuration suffers from strong backward radiation and reduced efficiency. In this article, a combined UC–PBG/ antenna structure is proposed to overcome the aforementioned drawbacks. The performance characteristics of a microstrip antenna positioned below a UC–PBG are examined using CST and Ansoft commercial software packages, which are based on the Finite Integration Technique (FIT) and the Finite Element Method (FEM), respectively. The proposed antenna demonstrates a remarkable improvement in the bore-sight gain, about 7.8 dBi at 2.64 GHz, compared with the corresponding conventional microstrip antenna and front-to-back ratio in excess of 22.8 dBi. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.

Design, fabrication, simulation, and measurement of a dual‐band, planar, compact artificial magnetic conductor

AbstractBy introducing two orthogonal gaps to a uniplanar compact photonic bandgap structure, artificial magnetic conductor's resonance frequencies have been significantly reduced. Since this compact pattern needs slots with 0.05‐mm width, the laser micromachining was explored to fabricate the prototypes. Reflection coefficients were measured through a WR‐137 waveguide. Considering the dominant waves propagating in a waveguide, a simulation method is introduced. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1524–1527, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24346

A compacted CMOS K‐band bandpass filter using meandering thin film microstrip and UC‐PBG structures

AbstractA compacted CMOS K‐band bandpass filter incorporating meandering thin film microstrip and defective uniplanar compact photonic bandgap (UC‐PBG) slow‐wave structures for size reduction are presented. Benefited from the multilayer metal technology of the standard 0.18‐μm CMOS process, meandering thin film microstrip and broadside‐coupled structures with large coupling degree are properly constructed to realize bandpass filters with small insertion loss. The slow‐wave effect of UC‐PBG structure is investigated and a center frequency drop of 14% is achieved by the use of UC‐PBG ground. A 3.6‐dB loss 18‐GHz filter with two transmission poles has been designed and implemented in standard 0.18‐μm CMOS technology and only with an area of 0.34 mm2. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 871–874, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24180

The forbidden bandgap characteristic of EBG structures

AbstractThe bandgap characteristics of several electromagnetic bandgap (EBG) structures are compared, and parametric studies of a wideband uniplanar compact photonic bandgap (UC‐PBG) structure are carried out. It has been presented that the bandgap bandwidth of the mushroom type EBG structure increases when a lower dielectric constant substrate is used or when a larger substrate thickness is used. However, for the UC‐PBG structures, which do not have shorting vias, the bandgap characteristic does not follow the trend as it is in the EBG structure with shorting via. Moreover, it is demonstrated that the bandgap frequency varies with the dielectric constant of the substrate, but the bandgap bandwidth does not have particular trend with the dielectric constant of the substrate. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2965–2967, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23804

Size reduction of microwave and millimeter‐wave passive circuits by UC‐PBG in standard 0.18‐μm CMOS technology

AbstractSize reduction of microwave and millimeter‐wave (mm‐wave) passive circuits incorporating a defective uniplanar compact photonic bandgap (UC‐PBG) slow‐wave structure is investigated. Benefited from the multilayer mental technology of the standard 0.18‐μm CMOS process, thin film microstrip structure is properly constructed on the lossy silicon substrate to reduce substrate loss. Defected periodic patterns on the ground plane are used to contribute to an enhancement of the effective dielectric constant and the slow‐wave factor is 14% increased by the use of UC‐PBG ground. Microwave and mm‐wave passive circuits including resonator and filter are designed and fabricated. Measured results show that the use of UC‐PBG ground has induced a frequency drop of 14% and validate the size reduction concept by using UC‐PBG. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2251–2254, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23643

A miniaturized patch antenna at 2.4 GHz using uni‐planar compact photonic band gap structure

AbstractThis article presents a miniaturized patch antenna for wireless applications at 2.4 GHz. A conventional microstrip‐fed patch antenna is firstly designed to operate close to 10 GHz. Then, the antenna is modified to operate at lower frequency without changing the antenna dimensions. First, the ground plane is replaced with a uniplanar‐compact‐photonic‐band‐gap (UC‐PBG) structure. Then, a backed conductor is placed close to the UC‐PBG and connected to it through four vias. These two modifications are utilized to decrease the lower operating frequency of the antenna from 9.7 to 2.42 GHz. Thus, a 75% size reduction factor is obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1360–1363, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23381

Compact ultra‐wideband bandpass filter using uniplanar compact photonic bandgap structure

AbstractA novel ultra‐wideband (UWB) bandpass filter in the whole UWB passband of 3.1–10.6 GHz is proposed and implemented using a uniplanar compact photonic bandgap (UC‐PBG) resonator for size reduction. Since the UC‐PBG structure has more distributed L‐C components than the conventional microstip multiple‐mode resonator (MMR), the size reduction is achieved, which is about 34% more than the UWB bandpass filter based on a conventional microstrip MMR. The proposed one‐stage UC‐PBG filter has four transmission poles, insertion loss &lt; 1.2 dB and group delay variation &lt; 0.14 ns, while the three‐stage one shows an insertion loss of &lt; 2.2 dB and a group delay variation of &lt; 0.4 ns in the whole UWB band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2122–2123, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22695

Characterization of Surface Wave Propagation in UC-PBG Patch Antenna by Using an Electrooptic Near-Field Mapping System

An electrooptic near-field mapping system based on a gain-switched distributed feedback (DFB) pulsed laser and a CdTe electrooptic crystal was used for characterizing stationary and transient near-field patterns of conventional and uniplanar compact photonic band gap (UC-PBG) patch antennas. Effect of the UC-PBG structure on reduction in surface waves in the UC-PBG patch antenna was experimentally verified by comparing stationary and transient near-field measurement of the conventional and UC-PBG patch antennas.

The Numerical Simulation of AMC Characteristics for Ucpbg on Grounded Dielectric Substrate

This paper aims to gain insights to physical mechanisms of an in-phase reflection of uniplanar compact photonic band-gap (UCPBG) on grounded dielectric substrate (GDS). The reflecting phase is discussed. The relationship between frequency and reference wavelength indicates that the cavity resonance is a most essential physical picture for zero-phase reflection. Moreover, the resonant model of cavity has more extensive applications than that of a lumped LC circuit. The dependence of artificial magnetic conductor (AMC) characteristics on the UCPBG parameters including individual period, patch array length, substrate thickness and permittivity are also evaluated. Some design guidelines have been obtained from the UCPBG structures design on the basis of our numerical simulations.

Full-wave analysis of bound and leaky modes propagating along 2D periodic printed structures with arbitrary metallisation in the unit cell

A full-wave numerical approach for the analysis and design of two-dimensional printed periodic structures on a grounded dielectric slab is presented. Electromagnetic band-gap surfaces, metamaterials and leaky-wave antennas are important special cases of structures that can be analysed. The proposed technique permits the analysis of an arbitrary metallisation within the unit cell; it is based on a mixed-potential integral equation solved by the method of moments in the spatial domain. Two-dimensional periodic vector and scalar Green&apos;s functions are derived in the spectral domain and an appropriate choice of the spectral determination for each spatial harmonic is performed to properly account for leakage effects. The proposed approach is used to calculate the real propagation wavenumber for surface waves in their pass-band regimes, propagating at arbitrary angles on two-dimensional periodic printed structures. Complex propagation wavenumbers can be derived as well for both bound modes in their stop-band regimes and proper and improper leaky modes in their relevant physical and non-physical regions. Results for a reference uniplanar compact photonic bandgap structure are reported demonstrating how the application of this rigorous technique provides a new detailed picture of the different modal behaviours and a more accurate determination of its band-gap zones.

Investigation of Surface-Wave Reduction in UC-PBG Patch Antenna by Using a Transient Electrooptic Near-Field Mapping Technique

A transient electrooptic near-field mapping system based on a gain-switched distributed feedback (DFB) pulsed laser and a CdTe electrooptic crystal was used for characterizing transient near-field patterns of conventional and uniplanar compact photonic bandgap (UC-PBG) patch antennas fabricated on a low-cost FR4 substrate. Effect of the UC-PBG structure on reduction in surface waves in the UC-PBG patch antenna was investigated experimentally by comparing transient near-field patterns of the conventional and UC-PBG patch antennas