Xue-Song Yang

Yagi Patch Antenna With Dual-Band and Pattern Reconfigurable Characteristics

This letter presents a slot-loaded Yagi patch antenna with dual-band and pattern reconfigurable characteristics. The beam can scan in the E-plane by switching the modes of the antenna, which is implemented by changing the states of the switches installed in the slots etched on the parasitic patches. Different modes of the antenna have different radiation patterns and operating frequency bands. There are three modes having a common band of 9.15-9.45 GHz and their beams direct to -7deg, +33.5deg, and -40deg in the E-plane. Two among three modes also have another common frequency band around 10.3 GHz and the main beams direct to +58.5deg and -62.5deg, respectively. The third mode also has another frequency band around 10.85 GHz and has a dual-beam pattern. Simulated and measured results are given and they agree well with each other. The antenna can be used in radar, satellite communications, etc

Jumping Genes Multiobjective Optimization Scheme for Planar Monopole Ultrawideband Antenna

A planar ultrawideband (UWB) monopole antenna is proposed in this paper. It has a planar multiple-trapezoidal monopole with adjustable dimensions. The proposed antenna is incorporated with the rectangular/rounded-corner ground plane to further improve the monopole performances such as impedance bandwidth. The geometric complexity of the antenna configuration is not easily devisable when the UWB performance criteria such as low voltage standing wave ratio (VSWR), minimal antenna size, omni-directional and uniform radiation pattern, and relatively constant gain over the ultrawide frequency band are to be simultaneously met. In this paper, all of these requirements can now be easily accomplished by making use of the recently developed jumping genes (JGs) multiobjective optimization scheme. A vivid demonstration of this approach of UWB design is to select an antenna configuration from the thoroughly investigated results and come up with the ultimate recommendation of hardware prototype fabrication. This way not only confirms both the simulated and measured results are all in good agreement but also indicates that the proposed methodology is sound for the design of UWB antenna.

Circularly Polarized Reconfigurable Crossed-Vagi Patch Antenna

A reconfigurable crossed-Vagi patch antenna (CYPA) that yields a circularly polarized pattern is proposed, and optimized by a novel Jumping-Genes Genetic Algorithm. This antenna is formed by two identical orthogonal reconfigurable linear Vagi patch arrays, around a single driven patch element. The main lobe of the reconfigurable crossed-Yagi patch antenna covers the elevation angles from 0° to 47° with a peak gain of 8.68 dBi. Full azimuthal coverage can be achieved by switching among the four antenna modes. The design justification has been duly demonstrated based on fabricated prototypes. The effect of a MEMS switch on the reconfigurable Vagi antennas is investigated. The reactance introduced by the switch can be offset by modifying the dimensions of a loaded slot. Due to the distinctive features of this antenna, satellite communications and global positioning systems would be the most suitable targets for application.

A Pattern-Reconfigurable Planar Fractal Antenna and its Characteristic-Mode Analysis

A compact pattern-reconfigurable planar fractal antenna is presented. Simulated and measured results showed that four switchable directional patterns, covering ranges from 300deg to 360deg and from 0deg to 60deg in the x-z and y-z planes, respectively, could be obtained around 8.4 GHz. The return losses were better than 10 dB. Finally, the pattern reconfigurability of the planar fractal antenna is described by means of a characteristic-mode analysis.

Polarization Reconfigurable Broadband Rectenna With Tunable Matching Network for Microwave Power Transmission

A broadband polarization reconfigurable rectenna is proposed, which can operate in three polarization modes. The receiving antenna of the rectenna is a polarization reconfigurable planar monopole antenna. By installing switches on the feeding network, the antenna can switch to receive electromagnetic (EM) waves with different polarizations, including linear polarization (LP), right-hand and left-hand circular polarizations (RHCP/LHCP). To achieve stable conversion efficiency of the rectenna (nr) in all the modes within a wide frequency band, a tunable matching network is inserted between the rectifying circuit and the antenna. The measured nr changes from 23.8% to 31.9% in the LP mode within 5.1-5.8 GHz and from 22.7% to 24.5% in the CP modes over 5.8-6 GHz. Compared to rectennas with conventional broadband matching network, the proposed rectenna exhibits more stable conversion efficiency.

Reconfigurable microstrip antenna design based on genetic algorithm

At present, there are two main domains to be researched for reconfigurable antennas; one is to reconfigure the radiation patterns at fixed operating frequencies, the other is to reconfigure the operating frequencies with uniform radiation patterns. However, the core of the desired characteristics of a modern reconfigurable antenna is that the antenna can reconfigure the radiation patterns over an extremely wide band. There is a large gap between present research and the ultimate objective. A novel reconfigurable microstrip antenna scheme is presented; it has advantages of low profile, light weight, conformability, and, especially, ease of fabrication and integration with RF devices. The finite-difference time-domain (FDTD) method and GA optimizers are used to optimize the antenna states according to the selected goals. We attempt to explore the possibilities of a microstrip antenna for reconfiguring radiation characteristics over an extremely wide band. The design results indicate that this antenna can obtain the required goals over an ultra-wide band through reconfiguring the states of the switch array installed in the shared aperture when it operates with the higher order modes.

A Compact Frequency Reconfigurable Rectenna for 5.2- and 5.8-GHz Wireless Power Transmission

A compact reconfigurable rectifying antenna (rectenna) has been proposed for 5.2- and 5.8-GHz microwave power transmission. The proposed rectenna consists of a frequency reconfigurable microstrip antenna and a frequency reconfigurable rectifying circuit. Here, the use of the odd-symmetry mode has significantly cut down the antenna size by half. By controlling the switches installed in the antenna and the rectifying circuit, the rectenna is able to switch operation between 5.2 and 5.8 GHz. Simulated conversion efficiencies of 70.5% and 69.4% are achievable at the operating frequencies of 5.2 and 5.8 GHz, respectively, when the rectenna is given with an input power of 16.5 dBm. Experiment has been conducted to verify the design idea. Due to fabrication tolerances and parametric deviation of the actual diode, the resonant frequencies of the rectenna are measured to be 4.9 and 5.9 GHz. When supplied with input powers of 16 and 15 dBm, the measured maximum conversion efficiencies of the proposed rectenna are found to be 65.2% and 64.8% at 4.9 and 5.9 GHz, respectively, which are higher than its contemporary counterparts.

A fractal Hilbert microstrip antenna with reconfigurable radiation patterns

A novel fractal microstrip patch antenna, which has the feature of linearly polarized reconfigurable radiation patterns, is proposed. By controlling RF MEMS switches on/off, two sets of connection states can be obtained at 10 GHz and the return losses are less than -20 dB. Simulated results show that the radiation patterns can be reconfigured in the upper half-space. Simulation results, given by Ansoft HFSS, are compared with simulation results by CST Microwave Studio, and a good agreement is observed.

Radiation Pattern Computation of Pyramidal Conformal Antenna Array with Active-Element Pattern Technique

Pyramidal microstrip conformal antenna arrays are analyzed with the use of the Active-Element Pattern (AEP) technique. The active-element patterns of typical elements can be computed effectively by dividing a large antenna, array into small subarrays. This results in a simplified analysis process for a conformal antenna array, and a reduction of the computational resources. Radiation patterns of the pyramidal arrays are computed with the use of the Active-Element Pattern technique, as well as full-wave simulation of the whole array. A comparison of the radiation patterns and computation times with the two methods is given, which illustrates the effectiveness and advantage of the new method.

A reconfigurable Hilbert curve patch antenna

A novel reconfigurable Hilbert curve patch antenna (RHCPA) is proposed. The patch is figured using the third order Hilbert curve. By introducing some slots, at least two configurations of the antenna with different radiation patterns are formed. By using micro-electro-mechanical systems (MEMS) switches to switch the configurations, the radiation patterns are reconfigured. Simulation results are given.