Directive photonic-bandgap antennas

This paper introduces two new photonic bandgap (PBG) material applications for antennas, in which a photonic parabolic reflector is studied. It is composed of dielectric parabolic layers associated to obtain a PBG material. The frequency gap is used to reflect and focus the electromagnetic waves. This device has been designed using a finite-difference time-domain (FDTD) code. FDTD computations have provided the theoretical reflector's directivity. These results are in good agreement with measurements, and it appears that the PBG reflector presents the same directivity as a metallic parabola. A second application uses a defect PBG material mode associated with a metallic plate to increase the directivity of a patch antenna. We explain the design of such a device and propose experimental results to validate the theoretical analysis     

Enhanced patch-antenna performance by suppressing surface wavesusing photonic-bandgap substrates

The microstrip patch antenna is a low-profile robust planar structure. A wide range of radiation patterns can be achieved with this type of antenna and, due to the ease of manufacture, is inexpensive compared with other types of antennas. However, patch-antenna designs have some limitations such as restricted bandwidth of operation, low gain, and a potential decrease in radiation efficiency due to surface-wave losses. In this paper, a photonic-bandgap (PBG) substrate for patch antennas is proposed, which minimizes the surface-wave effects. In order to verify the performance of this kind of substrate, a configuration with a thick substrate is analyzed. The PBG patch antenna shows significantly reduced levels of surface modes compared to conventional patch antennas, thus improving the gain and far-field radiation pattern     

平面带隙结构在微波和毫米波集成电路中的应用

介绍了平面带隙结构在微波集成电路应用方面的最新进展。光子带隙(PBG)结构是具有带阻特性的周期结构,最初应用于光学领域,后来扩展到其他领域。目前从可见光到红外都有研究,在微波和毫米波频段也有应用。PBG结构可以采用金属、介质、铁磁或铁电物质植入衬底材料,或者直接由各种材料周期性排列而成。目前国内外所提出的光子带隙结构多种多样,一维和二维的平面带隙结构由于易于实现且便于集成,因而在微波毫米波集成电路中得到了广泛的应用。     

Dual-frequency folded dipole antenna with PBG structure

For wideband RFID systems, a dual-frequency printed folded dipole antenna is designed with a photonic bandgap (PBG) structure carved in the antenna's arms. Simulated results show that this antenna has good return loss characteristic and hemisphere direction radiation characteristic, at two working centre frequencies of 0.90 and 2.24'GHz. Compared to other improved structures, the new PBG structure has special advantages in simplifying the antenna structure. Considering engineering processes, the influences of antenna arm width, dielectric loss, the PBG structure bore size and substrate on the performance of an antenna are particularly studied.     

Scan blindness free phased array design using PBG materials

Scan blindness occurs for phased arrays when propagation constants of Floquet modes (space harmonics) coincide with those of surface waves supported by the array structure. In this paper, we studied the possibility of using photonic band-gap (PBG) substrate to eliminate scan blindness. A specially designed printed PBG substrate can suppress surface wave propagation inside its bandgap range, therefore it can be used to eliminate scan blindness. In this paper, we presented a method of moments (MoM) analysis of the scan properties of dipole arrays on PBG substrates with ominidirectional bandgap(s). We found that scan blindness is completely eliminated. The elimination of scan blindness makes PBG materials very attractive in phased array design.     

Surface waves of printed antennas on planar artificial periodicdielectric structures

The characteristics of surface waves from a Hertzian (elementary) dipole on a multilayer structure with planar periodic material elements are investigated. An integral-equation moment method in conjunction with an analytical array scanning scheme is applied to the boundary-value problem associated with source interaction with infinite periodic structures. A pole-extraction technique and the saddle-point method are applied to find the far-zone periodic surface waves due to a current source. The investigation provides a fundamental study of surface wave properties of printed circuit antennas on planar artificial periodic (photonic bandgap) structures. It is found from the power patterns that surface waves are suppressed in the directions with wave bandgap and greatly enhanced in the directions just outside the bandgap zones. The surface wave pattern may be highly directive and the beam angle varies with frequencies. The finding suggests possible frequency-space selection devices. Experiments are carried out to validate the surface wave bandgap phenomenon and the beam angle frequency-selection property     

Modal impedances of planar, non-complementary, N-fold symmetric antenna structures

Planar N-arm rotationally symmetric antennas are commonly used in applications that demand wideband, multiple-mode, dual-polarization, and conformal geometries. Antennas included in this category are spirals, log-periodic dipole arrays, bow-tie antennas, and sinuous structures. An analytic expression for the modal impedances of these complementary planar structures has been available for many years. This paper extends the theory to non-complementary planar /V-fold symmetric antennas, and provides equations valid for any arm-to-gap width ratio, arm width, expansion rate, and low-loss electrically thin substrate materials. The equations are based on quasi-TEM coplanar stripline theory, and provide a band-averaged approximation of the input impedance of the antenna for each characteristic mode of operation. Predicted modal impedances are compared to spiral antenna measurements. In addition, a procedure for accurately measuring the dielectric constant of the substrate material is discussed.     

Periodic bandgap and effective dielectric materials in electromagnetics: characterization and applications in nanocavities and waveguides

The main objectives of this paper are to characterize and develop insight into the performance of photonic bandgap (PBG) periodic dielectric materials and to integrate the results into some novel applications. A powerful computational engine utilizing the finite-difference time-domain technique with periodic boundary conditions/perfectly matched layers integrated with Prony's method is applied to provide an in-depth look at the physics of PBG/periodic bandgap structures. Next, the results are incorporated into two classes of applications in the areas of nanocavity lasers and guidance of electromagnetic (EM) waves in sharp bends. A two-dimensional PBG structure with finite thickness is presented to strongly localize the EM waves in three directions and design a high-Q nanocavity laser. It is shown that the periodic PBG/total internal reflections remarkably trap the EM waves inside the defect region. The effect of the number of periodic cells and defect's dielectric constant on the Q of structure is investigated. It has been found that a seven-layer PBG with a dielectric impurity defect can be used in the design of a laser with a Q as high as 1050. Additionally, potential applications of the PBG structures for guiding the EM waves in sharp bends, namely, 90/spl deg/ and 60/spl deg/ channels are demonstrated. It is shown that shaping the bend by introducing small holes can noticeably improve the guidance of the waves at the bends and channel the EM waves with great efficiency. A comparative study between PBG and effective dielectric materials in controlling the EM waves is also provided and it is observed that the novel characteristics of the PBG cannot be modeled using the effective material for the frequencies within the bandgap.     

光子晶体结构贴片天线研究

采用时域有限差分法(FDTD)研究光子晶体带隙结构(PBG)对贴片天线性能的影响,设计了一种基于光子晶体结构的贴片天线,通过仿真,与普通贴片天线进行了对比.结果表明,通过添加光子晶体结构能提高天线增益.     

Novel Microstrip Photonic Bandgap Cell Structures

In general, a planar microstrip photonic bandgap (PBG) structure os a periodic array of holes etched in the ground plane of a microstrip line. To use a circuit with a PBG, the PBG structure cannot be fixed on a metal base and needs to be shielded. In this paper, two kinds of novel microstrip PBG unit cells with special patterns etched in the strip line, which can be used as the conventional microstrip circuits, are proposed and analyzed in detail. The results show that the transmission line theory is valid for the theoretic analysis of PBG circuits.     

Planar retrodirective array reflector using dual-slot antennas

An X-band planar reflector with a broad responding beam was developed using the Van Atta retrodirective antenna array. The reflector contained four antenna sub-arrays, each with six dual-slot antennas appropriately fed and paired by microstrip lines on the backside of the substrate. Good agreement has been achieved between theoretical and measured results     

新型电磁(光子)晶体贴片天线的研究进展

介绍了新型电磁（光子）晶体贴片天线的研究进展，尤其是几种新型光子晶体贴片天线。这些光子晶体贴片天线采用基底钻孔、地面腐蚀、加高阻抗表面以及基底上表面腐蚀等方法在贴处天线中加入光子晶体结构，改善了以高介电常数介质为基底的贴片天线的性能，也为贴片天线集成在微波电路上开辟了途径。光子晶体贴片天线这种集低剖面，易集成有好辐射性能于一身的新型天线，必将在移动通信等许多领域发挥作用。     

Investigation of Patch Antennas Based on Embedded Multiple PBG Structure

The method of finite-difference time domain was used, and characteristics of the patch antenna based on drilling air holes and embedding a metal boundary in the substrate were studied. The results indicate that the surface waves which propagate along the surface of the substrate can be suppressed by the multiple photonic band-gap structure because of its effect of forbidden band, that it can radiate most of electromagnetic waves' energy in the substrate significantly, and that it has lower return loss (S11) compared to the conventional patch antennas. Thus, a high gain is attained, its performance is improved. Due to these advantages, the extending use of photonic crystal patch antennas in the areas of mobile communication, satellite communication, aviation, etc., is expected.      

基于高阻抗表面PBG结构微带天线的设计与分析

以高介电常数介质为基底,利用辐射贴片开槽和微带馈电技术,设计了一款尺寸仅为16mm×12.45mm的小型微带天线。通过在此天线微带贴片周围加载高阻抗表面型光子晶体,有效抑制了表面波,改善了以高介电常数介质为基底的贴片天线的性能,实现了一款多频小型化PBG天线。HFSS仿真结果表明,加载高阻抗表面结构后的微带天线出现了三个谐振频点,分别为2.74、2.86和3.80GHz,其对应的增益分别达到6.02、8.38和5.69dB。所设计的光子晶体天线物理尺寸较小,方向性良好且具有多频特性,因此可为实际通信天线的应用提供参考。     

Development of Ultrawideband Antenna With Multiple Band-Notched Characteristics Using Half Mode Substrate Integrated Waveguide Cavity Technology

Investigations on planar ultrawideband (UWB) antenna with multiple band-notched characteristics based on half mode substrate integrated waveguide technology are presented. The proposed antenna consists of a planar UWB monopole antenna and a half mode substrate integrated waveguide cavity which can generate multiple stopbands by proper arrangement. Planar antennas with dual, triple and quadruple notched bands are designed and implemented. The notched frequencies and their bandwidths can be adjusted according to specification by altering the cavity and feed line independently. These antennas are fabricated with two-layer printed circuit board (PCB) process. Sharp and high band rejection, narrow frequency notches are achieved, which are in good agreement with the simulated results. This technique is suitable for designing wideband antenna with multiple frequency notches or for creating multiband antennas.      

Millimeter-wave and terahertz integrated circuit antennas

A comprehensive review of integrated circuit antennas suitable for millimeter and terahertz applications is presented. A great deal of research was done on integrated circuit antennas in the last decade, and many of the problems associated with electrically thick dielectric substrates, such as substrate modes and poor radiation patterns, have been understood and solved. Several antennas, such as the integrated horn antenna, the dielectric-filled parabola, the Fresnel plate antenna, the dual-slot antenna, and the log-periodic and spiral antennas on extended hemispherical lenses, which have resulted in excellent performance at millimeter-wave frequencies, are covered in detail. A review of the efficiency definitions used with planar antennas is included     

A novel TEM waveguide using uniplanar compact photonic-bandgap(UC-PBG) structure

A novel waveguide using a photonic bandgap (PBG) structure is presented. The PBG structure is a two-dimensional square lattice with each cell consisting of metal pads and four connecting lines, which are etched on a conductor-backed Duroid substrate. This uniplanar compact PBG structure realizes a magnetic surface in the stopband and is used in the waveguide walls to provide magnetic boundary conditions. A relatively uniform field distribution along the cross section has been measured at frequencies from 9.4 to 10.4 GHz. Phase velocities close to the speed of light have also been observed in the stopband, indicating that TEM mode has been established. A recently developed quasi-Yagi antenna has been employed as a broad-band and efficient waveguide transition. Meanwhile, full-wave simulations using the finite-difference time-domain method provide accurate predictions for the characteristics of both the perfect magnetic conductor impedance surface and the waveguide structure. This novel waveguide structure should find a wide range of applications in different areas, including quasi-optical power combining and the electromagnetic compatibility testing     

Considerations for millimeter wave printed antennas

Calculated data are presented on the performance of printed antenna elements on substrates which may be electrically thick, as would be the case for printed antennas at millimeter wave frequencies. Printed dipoles and microstrip patch antennas on polytetrafluoroethylene (PTFE), quartz, and gallium arsenide substrates are considered. Data are given for resonant length, resonant resistance, bandwidth, loss due to surface waves, loss due to dielectric heating, and mutual coupling. Also presented is an optimization procedure for maximizing or minimizing power launched into surface waves from a multielement printed antenna array. The data are calculated by a moment method solution.     

Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis

The paper presents a new concept in antenna design, whereby a photo-imageable thick-film process is used to integrate a waveguide antenna within a multilayer structure. This has yielded a very compact, high performance antenna working at high millimeter-wave (mm-wave) frequencies, with a high degree of repeatability and reliability in antenna construction. Theoretical and experimental results for 70 GHz mm-wave integrated antennas, fabricated using the new technique, are presented. The antennas were formed from miniature slotted waveguide arrays using up to 18 layers of photo-imageable material. To enhance the electrical performance a novel folded waveguide array was also investigated. The fabrication process is analyzed in detail and the critical issues involved in the fabrication cycle are discussed. The losses in the substrate integrated waveguide have been calculated. The performance of the new integrated antenna is compared to conventional metallic, air-filled waveguide antennas, and also to conventional microstrip antenna arrays operating at the same frequencies.      

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