基于单负传输线的宽带偶极子天线设计

提出了一种基于单负传输线的宽带偶极子天线。通过在偶极子天线的两臂上加载单负传输线结构单元,改变了传统偶极子天线上的电流分布,通过选取合适的电容、电感值,使天线的零阶、一阶谐振点相互靠近,从而实现宽带特性。仿真结果表明,天线的-10dB带宽达到了1.7GHz(2.3~4.0GHz),相对带宽达到了54%,较传统偶极子天线带宽明显展宽,实际测量结果与仿真结果吻合。天线在整个工作频带范围内,方向图保持了良好的一致性,天线的增益为2~3dBic,与传统偶极子天线相比有明显提高。     

A Compact Zeroth‐Order Resonant Antenna on Vialess CPW Single Layer

In this letter, a novel zeroth‐order resonant (ZOR) antenna on vialess co‐planar waveguide (CPW) is proposed. It is based on a composite right/left‐handed CPW transmission line. To achieve a compact size, this antenna utilizes the ZOR condition, and its reactive parameters determine the resonant frequency. Each unit cell is composed of a metallic top patch and meander lines. Since it is realized on the CPW single layer, the proposed antenna has the benefits of being a compact size and easy to fabricate. The bandwidth of 6.8% and efficiency of 62% are experimentally achieved. Its bandwidth is enhanced compared with other ZOR antennas.     

A Corner‐Fed Microstrip Circular Antenna with Switchable Polarization

In this paper, a design for a novel microstrip antenna with circular polarization diversity is proposed and experimentally investigated. This antenna is excited by a microstrip line, which is located at the corner of a circular patch. The polarization state can be switched electrically by setting a diode to on or off. The novel structure we describe here enables the optimization of the input match for both polarizations. From the measured result, good axial ratios are observed at the operating frequencies.     

Reconfigurable Ground‐Slotted Patch Antenna Using PIN Diode Switching

This letter presents a reconfigurable ground‐slotted patch antenna using a PIN diode connection in slots to achieve dual‐frequency operation. Slots in the ground plane increase the electrical length and thereby reduce antenna size by 53%. By controlling PIN diode conduction, we achieved band hopping while still satisfying the bandwidth requirements for K‐PCS and WiBro bands.     

Transmission Line Model for an Edge‐Coupled Patch Antenna

In this paper, a simple transmission line model for an edge‐coupled patch antenna is presented. The coupled section is modeled with a lump network which represents the mutual admittance between patches and from patch to ground. Theoretical analysis of two edge‐coupled patch antenna models are compared by simulation and experiment in antennas designed to operate at the 2 GHz band. The proposed model predicts the return loss of the antenna accurately.     

Planar DVB‐T Antenna Using a Patterned Helical Line and Matching Circuit

A miniaturized planar digital video broadcasting terrestrial (DVB‐T) antenna, which is composed of a patterned helical line, an open stub, and an impedance matching circuit on an FR4 (?_r=4.4) substrate for portable media player applications, is presented in this letter. The antenna has monopole‐like, omni‐directional radiation characteristics and a wide impedance bandwidth (VSWR<3) in the DVB‐T band from 174 MHz to 230 MHz at the VHF band.     

一种基于零阶谐振的双频电小天线设计

提出利用复合左右手传输线结构的零阶谐振设计一款具有双频特性的电小天线。该电小天线主要由介质基板、地面、加载了交指电容的贴片、弯曲线电感与圆角矩形虚拟地组成,具有电小尺寸特性(电尺寸为0.75)。该天线有两个工作频段,频段1的中心频率为1.22 GHz,频段2的中心频率为2.78 GHz,对应的相对带宽分别为3.28%和27.34%,同时覆盖了GPS L2(1220 MHz)与WiMAX(2500~2700 MHz)两个通信频段。天线在两个工作频段内均具有良好的辐射特性,频段1和频段2的平均峰值增益分别为1.0 dBi和1.72 dBi,平均辐射效率分别为53.12%和74.07%。最终对所设计的天线进行实物加工和测试,测试结果与仿真结果吻合良好。     

Polarization‐Diversity Cross‐Shaped Patch Antenna for Satellite‐DMB Systems

A small reconfigurable patch antenna is proposed to achieve polarization diversity for digital multimedia broadcasting systems at 2.6 GHz. To obtain polarization diversity, a pair of on‐slit PIN diodes is inserted in each diagonal of a cross‐shaped patch. Thus, four PIN‐diodes on these slits are utilized to change the connection of the slits and thus achieve polarization. Bias circuits for the diodes are allocated in the cutting corner of the cross‐shaped patch to minimize the antenna size. The antenna produces left‐hand circular polarization, right‐hand circular polarization, or linear polarization, depending on the PIN‐diode status. Analysis of circular polarization operation is explicated. Measurements show a gain of about 1.5 dB, a cross polarization of about ?20 dB, and an axial ratio of about 2.5 dB.     

Open‐Ended Two‐Strip Meander‐Line Antenna for RFID Tags

A new meander‐line antenna consisting of two open‐ended strips is proposed for a compact and broadband UHF radio frequency identification tag. An equivalent circuit model for the proposed antenna is derived and used to perform a simple and wideband impedance match to an arbitrary complex impedance of a tag chip without any additional matching network. The performance of the proposed antenna is validated by comparing calculated and measured results, which show good agreement.     

基于左右手传输线的小型天线设计

基于复合左右手传输线技术研究设计超小型的天线,通过对复合左右手传输线结构的适当调整获得一个零阶谐振天线,此时天线的工作频率不再依赖于天线的几何尺寸,而只与构成左手传输线的电感与电容相关,从而可大大降低天线的几何尺寸。文中基于复合左右手传输线设计了一款小型天线,使其可以工作在ISM频段,能够满足无线局域网(2.4~2.4835GHz)的要求。     

Open‐Ended Waveguide Antenna Using a Single Split‐Ring Resonator

This letter proposes an open‐ended waveguide antenna with a single split‐ring resonator. In contrast to the waveguide antennas incorporating multiple rings reported in a previous study, which exhibited narrow bandwidth, the proposed antenna uses only one ring to achieve broader bandwidth while keeping the aperture small. A single ring has a relatively low quality factor compared to multiple rings. The simulated and measured fractional bandwidth was 4.13% and 4.03%, respectively, which is much broader than the fractional bandwidth of about 1% demonstrated in a previous study. This simple technique can be used in many applications that require small apertures including near‐field probes and array elements.     

A Low‐Cost Method to Evaluate Absorber Reflectivity Using an Antenna with a Small Radiating Aperture and Frequency‐Domain Instrument

We propose a way to measure the absorber reflectivity at a low cost. Only one simple antenna with a small radiating aperture and a frequency‐domain instrument are utilized. The previously used equation for calculating the reflectivity of an absorber is inaccurate, and, therefore, a new equation is derived based on multiple reflection analysis and three test models. Notably, the reflection coefficient of the antenna is included in the derived equation. The accuracy of the proposed method is proven through simulation and measurements. It can be easily applied to a product examination by absorber manufacturers and customers owing to its advantages of simplicity, cost effectiveness, and non‐cutting examination.     

Reconfigurable Beam‐Steering Antenna Using Dipole and Loop Combined Structure for Wearable Applications

This paper proposes a reconfigurable beam‐steering antenna using a bended dipole and a loop. The radiation patterns of the two antennas are cancelled or compensated, and headed towards a specific direction when the dipole and loop antenna are combined at a reasonable ratio. The proposed antenna can steer the beam directions by controlling the operation of two artificial switches. The proposed antenna was manufactured on a PCB (FR‐4) and a flexible PCB (polyimide). In the case of the antenna that was fabricated on a PCB, the maximum beam directions were +50°, 0°, and –50° in the azimuth direction using the two artificial switches, and the antenna gain was 1.96 dBi to 2.48 dBi in the operation bandwidth of 2.47 GHz to 2.53 GHz. Also, the antenna was fabricated on a flexible PCB and measured under various bending conditions for wearable applications.     

Novel Shorted Meander‐Line USB Dongle Antenna with a Compact Ground Plane

This letter presents the design of a novel multiband USB dongle antenna with a compact ground plane. The radiating patch is composed of a modified meander‐line monopole and a shorted loop to generate a dual‐broadband resonance. The proposed antenna supports WiBro, Bluetooth, WLAN, WiMAX, and S‐DMB services. The total dimensions of the fabricated antenna are 10 mm × 45 mm × 1 mm, the most compact size among multiband USB dongle antennas reported to date. The measured 10 dB reflection loss bandwidths are 20.8% (2.24 GHz to 2.76 GHz) and 20.2% (4.86 GHz to 5.95 GHz). The measured peak gain is 2.97 dBi, and efficiency is higher than 58%. In addition, the radiation pattern approximates an omnidirectional pattern.     

Enhanced‐Gain Planar Substrate‐Integrated Waveguide Cavity‐Backed Slot Antenna with Rectangular Slot Window on Superstrate

A novel substrate‐integrated waveguide (SIW) cavity‐backed slot antenna is proposed in this study to achieve enhanced‐gain performance. The peak gain is remarkably improved with the use of an SIW cavity and metallic superstrate. The superstrate comprises a single rectangular slot window and two half‐wavelength patches. The gain can be enhanced by combining the in‐phase radiating fields. Further, the 10 dB bandwidth of the proposed antenna ranges from 2.32 GHz to 2.49 GHz, which covers the wireless local area network band. The measured peak gain is 9.44 dBi at 2.42 GHz.     

Differential Dual‐Frequency Antenna for Wireless Communication

A novel differential dual‐frequency antenna using proximity coupling is proposed. Dual bands are realized by a slot in the ground plane. The lower resonant frequency is controlled by the slot in the ground plane, and the upper resonant frequency is mainly determined by the dimensions of the radiating patch. Measured results show that the proposed antenna can operate at 2.51 GHz and 5.38 GHz.     

Dice‐Five Polarization‐Agile Corner‐Fed Patch Array Antenna

A novel planar polarization‐agile microstrip subarray is proposed and its performance assessed by a thorough numerical investigation. The subarray consists of five square patches with a central element, directly coupled to a pair of microstrip feed lines by a cross‐shaped aperture, which spreads the power outwards to the other patches through a network of suitable connections. By properly exciting the antenna at its input ports, any kind of polarization of the radiated field can be accomplished with fairly low cross‐polarization levels. Moreover, since only two feed lines are required to drive the whole subarray, polarization agility is simply and attractively achieved by a single phase‐shift circuit. The design concept is described and the results of the analyses and simulations performed by two completely independent full‐wave approaches are presented and discussed.     

A High‐Gain Microstrip Patch Array Antenna Using a Superstrate Layer

A dielectric superstrate layer above a microstrip patch antenna has remarkable effects on its gain and resonant characteristics. This paper experimentally investigates the effect of a superstrate layer for high gain on microstrip patch antennas. We measured the gain of antennas with and without a superstrate and found that the gain of a single patch with a superstrate was enhanced by about 4 dBi over the one without a superstrate at 12 GHz. The impedance bandwidths of a single patch with and without a superstrate for VSWR < 2 were above 11%. The designed 2×8 array antenna using a superstrate had a high gain of over 22.5 dB and a wide impedance bandwidth of over 17%.     

Analysis of Single‐RF MIMO Receiver with Beam‐Switching Antenna

This paper proposes a single‐RF MIMO receiver that adopts a beam‐switching antenna (BSA) instead of a conventional array antenna. The beauty of the proposed single‐RF MIMO receiver with BSA is that it can be deployed in a very small physical space while achieving a full spatial multiplexing gain. Our analysis has revealed that the use of a BSA inevitably results in the spectrum spreading effect at the RF output, which in turn causes an SNR decrease and adjacent channel interference (ACI). Two novel receiver techniques are proposed to mitigate the issues of redundant sub‐band suppression and ACI avoidance. Numerical analysis results verify the performance improvement from the proposed receiver techniques.     

High‐Performance Dual‐Circularly Polarized Reflector Antenna Feed

This paper presents a high‐performance dual‐circularly polarized feed employing a dielectric‐filled circular waveguide. Novel features are incorporated in the proposed feed, such as a dielectric rod radiator for high gain and good impedance matching; dual quarter‐wave chokes for low axial ratio over wide angles and for low back radiation; an integrated septum polarizer; and two end‐launch‐type coaxial‐to‐waveguide transitions. The proposed feed shows excellent performance at 5.0 GHz to 5.2 GHz.