Yagi-Uda Antenna Research Articles

Experiments with dipole antennas

Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a variant of the Yagi–Uda antenna is explored. The experiments are suitable as laboratory works and classroom demonstrations, and are attractive for student projects.

Design of Short Microstrip Leaky-Wave Antenna With Suppressed Back Lobe and Increased Frequency Scanning Region

We demonstrate a short (1.08lambdao) microstrip leaky-wave antenna (MLWA) with suppressed back lobes and doubled frequency scanning region. The configuration of the proposed LWA contains three parts: the conventional open structure MLWA, the added monopole connected to the end of the MLWA on a defected ground plane, and the Yagi-Uda-like elements fabricated along the monopole. Because of the open structure of the MLWA, the reflected power produces a large back lobe radiated backwardly. By using the method of the added monopole connected to the end of the antenna, the remainder power could radiate through the added monopole without reflecting at the end. In addition, the Yagi-Uda-like elements fabricated along the added monopole enlarge the frequency scanning region due to the Yagi-Uda antenna characteristic. Compare to the conventional MLWA, the back lobe of the proposed LWA is suppressed about 8 dB at 5.0 GHz. The frequency scanning region of the H-plane (YZ-plane) of the proposed LWA can scan from 34deg to 57deg (total 23deg) while the frequency is operated from 4.6 GHz to 5.0 GHz; meanwhile the conventional MLWA scans from 30deg to 41deg (only 11deg) at the same frequency region.

CPS 급전 방식의 광대역 Yagi-Uda 안테나

본 논문에서는 CPS 급전 방식의 광대역 Yagi-Uda 안테나를 제안하였다. 제안한 안테나는 CPS 급전 선로를 사용하여 기존에 설계된 Yagi-Uda 안테나들에 비하여 간단한 급전 구조를 가지며 기판에 접지면이 필요 없기 때문에 reflector의 설계를 자유로이 할 수 있다. 정합 선로를 설계하기 위하여 선폭이 두꺼운 선로와 선폭이 얇은 선로 사이에 테이퍼된 선로를 삽입하여 최적의 CPS 급전 선로 구조를 설계하였다. 제안한 Yagi-Uda 안테나는 -10 dB 반사 손실을 기준으로 <TEX>$3.9{\sim}5.9$</TEX> GHz의 대역폭을 가지고 대역폭 내에서 <TEX>$6.5{\sim}8$</TEX> dBi의 이득을 가진다. 중심 주파수인 4.9 GHz에서 이득은 7.4 dBi 이고, 반전력 빔폭은 x-z 평면에서 <TEX>$98^{\circ}$</TEX>, x-y 평면에서 <TEX>$73^{\circ}$</TEX>이다. This paper presents a broadband CPS-fed Yagi-Uda antenna. The antenna has a feedline structure much simpler than other Yagi-Uda antennas and it provides more design flexibility in arranging the reflector. To improve the impedance matching, a tapered CPS line is inserted between the thick and thin feedlines. The proposed antenna exhibits the bandwidth of <TEX>$3.9{\sim}5.9$</TEX> GHz (|G| < -10 dB) and the gain of <TEX>$6.5{\sim}8$</TEX> dBi within that bandwidth. At the center frequency of 4.9 GHz, the antenna shows the gain of 7.4 dBi, and HPBW of <TEX>$98^{\circ}$</TEX> along the x-z plane and <TEX>$73^{\circ}$</TEX> along the x-y plane.

Switchable Printed Yagi-Uda Antenna with Pattern Reconfiguration

A switchable Yagi-Uda antenna prototype with radiation pattern reconfiguration is presented in this letter. The proposed reconfigurable antenna is based on the concept of switching between the reflector and director of a Yagi-Uda antenna using a radio frequency PIN diode. As a result, the minimum/maximum radiation can be steered towards desired signals or away from interfering signals in opposite directions. The measured 10 dB impedance bandwidth and gain are 210 MHz (7%) and 8.02 dBi at 3 GHz, respectively. Details of the antenna design and its performance are described and empirically analyzed.

높은 입력 임피던스를 가지는 테라헤르츠 Yagi-Uda 안테나

In this paper, a THz Yagi-Uda antenna with high input impedance is designed. By placing the antenna on a thin substrate, end-fire radiation patterns with high antenna impedance can be obtained even when the substrate has high relative dielectric constant. The proposed Yagi-Uda antenna has high input resistance of approximately at the resonance frequency which is obtained by using a U-shaped dipole as a driver element. It is expected that the Yagi-Uda antenna on a thin substrate can achieve much higher terahertz output power than the conventional THz antennas.

Monotonically Improving Yagi-Uda Conflicting Specifications Using the Dominating Cone Line Search Method

Given a non-optimal Yagi-Uda antenna, this paper presents a technique to improve simultaneously and monotonically all its conflicting specifications. This is possible using the multiobjective optimization technique called Dominating Cone Line Search. Results for a 6 elements antenna, considering 3 conflicting specifications in 3 different frequencies, thus, a 9 objectives optimization problem, is presented.

A NOVEL WIDE-BAND MICROSTRIP YAGI-UDA ARRAY ANTENNA FOR WLAN APPLICATIONS

This paper presents a design of Wide-Band Microstrip Yagi-Uda antenna with high gain and high front to back (F/B) ratio. Numerical and measured results of our design show more than 18dB front to back ratio at 5.5GHz and no backward radiation at 5.2GHz. An impedance bandwidth of 22.05% was achieved around 5.5GHz. The antenna gain (10{12.4dBi) can be varied to be suitable for various applications. Measured return loss and radiation pattern of this antenna is presented to validate the results of simulations by two methods. The flrst method based on flnite element method (FEM) and the second one based on flnite integral technique (FIT) were used to analyze antenna structure, and subsequently the Genetic Algorithm (GA) was applied by using HFSS simulator to obtain the optimized parameters. In order to flnd the best design method for this antenna, the efiect of distance between the parasitic elements of proposed antenna was studied. Finally two microstrip Yagi-Uda array antennas were combined to increase the gain of antenna. To demonstrate the major beneflts, a comparison of our initial and flnal designs of Yagi-Uda antenna is provided.

Optimization Technique Using Differential Evolution for Yagi-Uda Antennas

Differential Evolution (DE) can solve multi-objective optimization problem in an extremely efficient manner. Based on thin wire modeling, method of moments code is developed for evaluating the antenna designs. DE is employed to optimize the geometric parameters of Yagi-Uda antennas. The length and spacing of Yagi-Uda antennas are optimized variables. The results clearly show that the DE is a robust and useful optimization tool for designing antennas.

Broadband CPS-fed Yagi-Uda antenna

A broadband coplanar stripline-fed Yagi-Uda antenna is presented. The antenna has a feedline structure that is much simpler than other Yagi-Uda antennas, and provides more design flexibility in arranging the reflector owing to the absence of a large ground plane. To improve the impedance match, a taper is inserted between the wide-line/small-gap and the narrow-line/large-gap CPS. The proposed antenna has a bandwidth of 3.9–5.9 GHz for a −10 dB reflection coefficient and a gain of 6.5–8.0 dBi. At the centre frequency of 4.9 GHz, the antenna has gain of 7.1 dBi, and a half-power beamwidth (HPBW) of 73° in the E-plane and 98° in the H-plane.

A Bi-Swarm Optimizing Strategy and its Application of Antenna Design

A global optimization strategy based on Differential Evolution (DE) is proposed. The new optimization strategy divides the total population into two swarms, assimilative and evolutionary swarms. The different operations to generate offspring vector are implemented in different swarms. In each generation, the best member of evolutionary swarm will be exalted to join in the assimilative swarm to replace the worst performance member. For verifying the efficiency of the new optimization strategy, some Yagi-Uda antennas are optimized as examples. The results show that the new global optimizer is robust for multi-modal objective function optimization.

Novel Antenna Concept for Compact Millimeter-Wave Automotive Radar Sensors

An antenna concept for compact millimeter-wave radar sensors that desire a fan-beam radiation pattern is proposed. It combines an end-fire antenna on a ceramic substrate with a cylindrical parabolic reflector that can be integrated in the sensor's metal housing. The concept allows a direct interconnection from the active components to the antenna in a flip-chip attachment. It is validated with a 77-GHz Yagi-Uda antenna on a 127- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mu</i> m thick Alumina substrate by measurements with a probe-based measurement setup. The measured return loss, gain, and radiation patterns of the antenna without and with the reflector are given.

Koch-Fractal Yagi-Uda Antenna

A Yagi-Uda antenna constructed of three Koch fractal elements is presented. Simulated and measured characteristics of the antenna shows a half-power beam-width of 64° achieved with dimensions below a third of a wavelength. Furthermore, the Koch dipole and its size miniaturization capabilities are investigated.

Broadband Planar Antenna Combining Monopole Element with Electromagnetic Bandgap

New structure of broadband planar antenna, combining monopole elements with electromagnetic bandgap (EBG) structures, is proposed. The antenna has a simple single layer structure and unique beam pattern. Antenna is fabricated on a surface of a single layer dielectric substrate and back side of the substrate is covered with metal layer. At the center of the substrate, an inverted L monopole strip is fabricated and on both sides of this monopole, EBG unit cells are placed. By tuning monopole length and EBG bandgap frequency, the monopole resonates even if metal layer exists close to the monopole radiator. Three types of EBG, one dimensional (1D), square two dimensional (2D) and hexagonal 2D, are tested. By combining monopole strip with hexagonal 2D-EBG, the bandwidth of prototype antenna, whose return loss is less than 10dB, is 840MHz in 5GHz band. To control beam patterns of antenna, parasitic elements are placed close to the monopole radiator and EBGs. These parasitic elements work as directors of quasi Yagi-Uda antenna and radiation gain at lower tilt angles is improved.

Development of microwave imaging reflectometry in large helical device

Three key devices of the microwave imaging reflectometry (MIR) are under development in large helical device (LHD). The 2-D mixer array is developed by stacking the one-dimensional array of the planar Yagi-Uda antenna. The new type of the bandpass filter bank is modified to match the requirement of the MIR. The low-cost quadrature demodulator is also developed for the phase detection system. By using the low-price commercial wireless devices, the development cost becomes much lower than the expensive waveguide system. These devices enable the development of 2-D/3-D microwave imaging system for the plasma diagnostics and industrial applications.

Enhanced directional excitation and emission of single emitters by a nano-optical Yagi-Uda antenna

We demonstrate by 3D numerical calculations that the interaction of a single quantum emitter with the electromagnetic field is both enhanced and directed by a nano-optical Yagi-Uda antenna. The single emitter is coupled in the near field to the resonant plasmon mode of the feed element, enhancing both excitation and emission rates. The angular emission of the coupled system is highly directed and determined by the antenna mode. Arbitrary control over the main direction of emission is obtained, regardless of the orientation of the emitter. The directivity is even more increased by the presence of a dielectric substrate, making such antennas a promising candidate for compact easy-to-address planar sensors.

Enhanced directional excitation and emission of single emitters by a nano-optical Yagi-Uda antenna.

Enhanced directional excitation and emission of single emitters by a nano-optical Yagi-Uda antenna.

Optimization of the Yagi-Uda Antenna for Gain, Impedance, and Sidelobes Using Simulated Annealing

The Yagi-Uda antenna is being widely used for VHF/UHF applications. Depending on the particular application, there are different design goals to be met. Several techniques, such as gradient-based method, genetic algorithms, and particle swarm optimization, have been used for optimization of the Yagi-Uda antenna for different design objectives. Simulated annealing (SA) is a stochastic global optimization technique, which has been used successfully for the optimization of antenna arrays. In this article, the use of SA for optimization of gain, impedance, and sidelobe level of the pattern of the Yagi-Uda antenna has been presented. To evaluate the performance of the designs, a method of moments code NEC2 has been used. The results obtained show superiority of SA over other methods.

고출력 테라헤르츠파 발생을 위한 새로운 구조의 Yagi-Uda 안테나

본 논문에서는 테라헤르츠 대역에서 동작하는 새로운 구조의 Yagi-Uda 안테나를 설계하였다. 제안한 Yagi-Uda 안테나는 안테나의 driver를 반 파장 다이폴이 아닌 전 파장 다이폴을 사용함으로써 공진주파수에서 <TEX>$2000{\Omega}$</TEX> 정도의 높은 입력 저항을 얻을 수 있었다. 바이어스 선에 Photonic Bandgap 구조를 적용하여 바이어스 선로로의 전류누설을 최소화 하였고, 안테나를 얇은 기판에 설계함으로써 기판의 비유전율로 인한 안테나의 임피던스 저하를 막고 Yagi-Uda 안테나 고유의 단방향 지향적인 복사특성을 나타나게 하였다. 따라서 제안한 Yagi-Uda 안테나는 포토믹서와의 임피던스 부정합 문제를 개선하여 테라헤르츠파의 출력을 증가 시킬 수 있을 것이라 예상한다. In this paper, a new type of Yagi-Uda antenna that operates in the terahertz frequencies is designed. The proposed Yagi-Uda antenna can obtain high input resistance of approximately <TEX>$2000{\Omega}$</TEX> at the resonance frequency by using a full-wavelength dipole instead of a half-wavelength dipole as the driver element. The current leakage into the bias line was minimized by applying the photonic bandgap structure to the bias line. By designing the antenna on a thin substrate, the impedance lowering of an antenna caused by the relative dielectric constant of the substrate was prevented and the end-fire radiation pattern which is the original radiation characteristic of the Yagi-Uda antenna could be obtained. We expect that the proposed Yagi-Uda antenna can achieve increased terahertz output power by improving the impedance mismatching problem with the photomixer.

Optimization of Yagi-Uda Antenna Using Simulated Annealing

Simulated annealing (SA) is a stochastic global optimization technique, which has been used successfully for optimization of antenna arrays. In this paper, the use of SA for optimization of gain, impedance and bandwidth of the Yagi-Uda antenna has been presented. To evaluate the performance of designs, a method of moments code NEC2 has been used. Comparative results indicate superiority of using SA over other methods.

Performance of Circular Yagi-Uda Arrays for Beamforming Applications Using Particle Swarm Optimization Algorithm

In this paper, a circular Yagi-Uda array (CYUA) for smart antenna applications is designed using the lengths and spacings from the optimum design of a three-element linear Yagi-Uda antenna. Then a modified circular Yagi-Uda array (MCYUA) is developed by adding 5 circular connecting wires to the inner parasitic elements (reflectors) to form a wire grid cylinder. The results are compared with those for uniform circular array (UCA) with 12 half-wave dipole elements. In our analysis, the method of moments (MoM) is used to compute the response of the arrays in a mutual coupling environment. The particle swarm optimization (PSO) algorithm is used to optimize the complex excitations of the adaptive arrays elements for beamforming.