Junping Geng

Printed Omni-Directional UWB Monopole Antenna With Very Compact Size

A compact rectangular monopole with an equal-width ground plane is presented. This novel structural configuration could significantly improve its radiation performance and decrease its size. The feeding structure composed of a trident-shaped strip and a tapered impedance transformer is presented and discussed. Its impedance bandwidth, defined by measured VSWR less than 2, is from 2.75 to 16.2 GHz with a ratio of about 5.9:1. Both numerical and experimental results show that the proposed monopole antenna has stably omni-directional H-plane radiation patterns with low cross-polarization level within its impedance bandwidth. This novel monopole antenna has ultrawide impedance bandwidth, very compact size (30 mm*8 mm), low fabrication lost, and omni-directional H-plane radiation patterns, which are suitable for various broadband applications.

E-Shape Patch With Wideband and Circular Polarization for Millimeter-Wave Communication

E-shape patch antenna is proposed for millimeter wave frequencies. Using this E-shape structure, the patch antenna is designed for wideband operation at about 31.6-40 GHz for millimeter wave communication. Simulated and measured results for main parameters such as return loss, impedance bandwidth, radiation patterns and gains are also discussed herein. The study shows that modeling of such antennas, with simplicity in designing and feeding, can well meet millimeter-wave wireless communication.

On the Performance of Printed Dipole Antenna With Novel Composite Corrugated-Reflectors for Low-Profile Ultrawideband Applications

An investigation of the performance of printed dipole antenna with finite periodically corrugated-reflectors for low-profile ultrawideband (UWB) applications is presented. According to the relative orientations of the linear-polarized source antenna and the corrugated-reflectors, the problem could be divided into H and E cases. Their fundamental differences and design guidelines are discussed in detail. A novel composite corrugated-reflector based on the combinations of H-type and E-type ones is proposed for the first time, and fully characterized with a UWB source dipole which was optimized in the free space for better comparisons. An example antenna with only 21 mm core profile, composed of a printed UWB dipole, a microstrip balun and a composite corrugated-reflector, has an impedance bandwidth of 2.75 GHz to 8.35 GHz. Both numerical and experimental results show that the example antenna also has stable uni-directional radiation patterns and a realized gain of over 6 dB within the frequency band from 2.3 to 6.0 GHz, which could be a decent alternative to the EBG antennas due to significant improvements on pattern and gain bandwidth.

A Single-Layer Ultrawideband Microstrip Antenna

A single-layer microstrip antenna for ultrawideband (UWB) applications, in which an array of rectangular microstrip patches was arranged in the log-periodic way and proximity-coupled to the microstrip feeding line, is presented. In order to reduce the number of microstrip patches in the UWB log-periodic arrays, a large scale factor k = 1.1 was firstly reported and proved to be highly effective. Furthermore, instead of using an absorbing terminal loading, a novel loss-free compensating stub was proposed. Detailed parameters study was also presented for better understanding of the proposed antennas. The impedance bandwidth (measured VSWR < 2.5) of an example antenna with only 11 elements is from 2.26-6.85 GHz with a ratio of about 3.03:1. Both numerical and experimental results show that the proposed antenna has stable directional radiation patterns, very low-profile and low fabrication cost, which are suitable for various broadband applications.

Design of a CPW-fed Ultra Wideband Crown Circular Fractal Antenna

A new ultra wideband antenna fed by coplanar waveguide (CPW) is presented in this paper. A fractal structure is constructed to obtain ultra wideband (UWB) performance. The parameters and characteristics of the antenna and the simulation results show that the 6:1 or more bandwidth is achieved with the second order iterative antenna structure

A Broadband Dual Circularly Polarized Patch Antenna With Wide Beamwidth

A broadband dual circularly polarized patch antenna with wide beamwidth is presented. The patch is excited by four cross slots via a microstrip line with multiple matching segments underneath the ground plane. The four cross slots and the multiple matching segments are optimized simultaneously to obtain the best performance. Measurements show that the antenna has 10-dB return-loss bandwidth of 24%, 10-dB isolation bandwidth of 19%, 3-dB axial-ratio bandwidth of 16%, and beamwidth of 110 °. Moreover, the single feed makes it a good candidate for array design.

Numerical Study of the Near-Field and Far-Field Properties of Active Open Cylindrical Coated Nanoparticle Antennas

A very electrically small, active open cylindrical coated nanoparticle model is constructed, and its electromagnetic properties are investigated in the visible frequency band. Its optical response under both planewave and electric dipole antenna excitations shows very strong dipole behavior at its lowest resonance frequency. The scattering cross section at that dipole resonance frequency is increased by more than +50 dBsm for the planewave excitation. When the open structure is excited by a small current (I0 = 1 ×10-3A) driven dipole antenna, the maximum radiated power of the composite nanoantenna can be increased by +83.35 dB over its value obtained when the dipole antenna radiates alone in free space. The behaviors under various locations and orientations of the dipole are explored. Dipole orientations along the cylinder axis and symmetric locations of the dipole produced the largest radiated power enhancements.

Printed Binomial-Curved Slot Antennas for Various Wideband Applications

This paper presents a new design of wide slot antenna for various wideband applications. The proposed printed antenna consists of a slot and a turning stub, both formed by a binomial curve function; thus, various bandwidths (BWs) can be obtained based on the structure with different binomial curves. Some key parameters affecting the antenna performance have been analyzed and discussed in detail as an antenna design guideline. To validate the theoretical design, six prototypes of various binomial-curved slot antennas were designed, fabricated, and measured. Good agreement between the simulated results and the measured ones is observed. The results demonstrate that the proposed type of antenna can obtain a BW range from 9.8% to 99.7% for VSWR ≤ 2 by selecting various binomial-curved slots, which may provide a convenience for various wideband antenna designs. Moreover, the proposed type of antenna owns a simple structure and a stable gain of about 3-5.5 dBi, which is very suitable for wideband wireless system applications.

High-Gain Planar Antenna Arrays for Mobile Satellite Communications [Antenna Applications Corner]

Two large and low-profile panel antenna arrays, used as receiving and transmitting antennas for mobile satellite communications, are described. The receiving and transmitting arrays have overall dimensions of 120 cm × 20.7 cm × 1.3cm and 107.5 cm × 20.4 cm × 1.7 cm, respectively. They exhibit high gains and adequate efficiencies, due to integrated array designs. For the receiving panel array, a method using a number of high-efficiency subarrays, combined with a novel active integrated global feed network, is proposed. For the transmitting panel array, a number of high-efficiency subarrays, together with a novel compact waveguide feed network, is employed. Based on the above techniques, two large panel antenna arrays were successfully developed. We present the detailed designs of the subarrays, the passive and active feed networks, and the vertical transitions. Simulated and experimental results showed that the designed receiving and transmitting panel arrays achieved measured gains and efficiencies of 34.1 dBi and 48.2%, and 33.5 dBi and 36.3%, respectively, in each band. This indicated that the proposed antenna panels are good candidates for future satellite communications applications.

PULSE PRESERVING CAPABILITIES OF PRINTED CIRCULAR DISK MONOPOLE ANTENNAS WITH DIFFERENT SUBSTRATES

This paper presents a theoretical investigation on the pulse preserving capabilities of the CPW-fed circular disk monopole antennas at the assistance of correlation factors. The distortions of the radiated signals, which are mainly caused by the bandwidth mismatch between the antennas and the source pulse, are alleviated by using suitable source pulse. The ringing and pulse-width spreading of the radiated signals caused by the energy-storage effects of the dielectric substrate are discussed in detail. Possible improvement solutions and an example are provided. The improvement of the correlation factors introduced by selecting suitable substrate parameters is about 7% on an average. With the physical insight and design example, the proposed solutions are expected to find applications in the design of printed UWB monopole antennas for better pulse preserving capabilities.