Diamond Dipole Research Articles

On human body transmission wearable diamond dipole antennas above engineered jackets

This paper presents the propagation of dual-band diamond dipole antenna on three various jackets. The jackets are purely fleece fabric with Shieldit fabric patches on top of it. The network analyzers with the flexible lossless coaxial cable are used to measure the communication of the antennas. The experiment involves a man with ideal body mass index (BMI) wearing the jackets by placing the flexible antennas on top of it. It is observed that the best on-body communication is by wearing the engineered jacket. The 10 dB improvements are observed when the antenna is positioned on top of engineered jacket contrast to the regular jacket. In other words, the performance of the antenna is also be determined by antenna placement. High transmission lossesses cause the antenna mismatch when the antennas are positioned above the full conductive jacket.

On-Body Transmission Single-Band Diamond Dipole Antenna with Waveguide Jacket

This paper presents the investigation of on-body transmission single-band diamond dipole antenna with three different jackets. The jackets are named as normal jacket, grounding jacket and waveguide jacket. The on-body transmission is measured using two flexible single-band antennas attach to the jackets. A man with the height of 180 cm and 75 kg weight becomes as a model for the real measurement. The measurement is conducted in small space area by using portable network analyzer with flexible network cable. The measurement results show that the best performance for on-body transmission is with waveguide jacket. 10 dB transmission improvement is archived when the antenna is placed above the waveguide jacket compared to the normal jacket. It is found that the transmission of the antenna is also depends on the antenna orientation and further transmission lossess occur when the antennas are placed above the grounding jacket.

Enhanced Broadside Gain of an Ultrawideband Diamond Dipole Antenna Using a Hybrid Reflector

This communication studies the effect of a hybrid reflector on the radiation pattern of an ultrawideband diamond dipole antenna. The cause of a split radiation pattern in the broadside direction appearing when using a uniform artificial-magnetic-conductor-based reflector is investigated and is found to be due to destructive interference in the broadside direction produced by surface currents localized in certain areas of the reflector. A hybrid reflector is then proposed to mitigate this problem using both electrical and magnetic conductors. This solution enhances the gain in the broadside direction of the ultrawideband antenna. A complete antenna with a feeding system and a hybrid reflector has been fabricated and the measurement results are presented.

Textile Diamond Dipole and Artificial Magnetic Conductor Performance under Bending, Wetness and Specific Absorption Rate Measurements

Textile diamond dipole and Artificial Magnetic Conductor (AMC) have been proposed and tested under wearable and body centric measurements. The proposed antenna and AMC sheet are entirely made of textiles for both the substrate and conducting parts, thus making it suitable for wearable communications. Directive radiation patterns with high gain are obtained with the proposed AMC sheet, hence minimizing the radiation towards the human body. In this study, wearable and body centric measurements are investigated which include bending, wetness and Specific Absorption Rate (SAR). Bending is found not to give significant effect to the antenna and AMC performance, as opposed to wetness that yields severe performance distortion. However, the original performance is retrieved once the antenna and AMC dried. Moreover, notable SAR reduction is achieved with the introduction of the AMC sheet, which is appropriate to reduce the radiation that penetrates into human flesh.

Vertical and horizontal transmission enhancement between antennas using textile artificial magnetic conductor waveguide sheet

A textile artificial magnetic conductor (AMC) waveguide sheet with a textile diamond dipole is proposed to improve wireless on-body transmission. The sheet-like waveguide provides an independent transmission path which can reduce the performance degradation caused by the human body. The proposed AMC sheet is made entirely of textiles for both the substrate and the conducting parts, thus making it suitable for wearable communications. Transmission characteristics between antennas are studied rigorously in free space and on-body environments. Significant transmission enhancement is observed for all the tested orientations and positions for both free space and on-body placements. With the presence of the AMC, the S 21 has peaks of up to a maximum of −9.9 dB. This textile AMC sheet constitutes a new approach for efficient wearable wireless body-centric communications.

TEXTILE ARTIFICIAL MAGNETIC CONDUCTOR WAVEGUIDE JACKET FOR ON-BODY TRANSMISSION ENHANCEMENT

Diamond dipole antennas with textile Artiflcial Magnetic Conductor (AMC) sheet-like waveguide were designed to investigate the possibility of improving transmission between antennas. Fleece fabric is used as the substrate of the textile AMC while SHIELDIT fabric is used as the conductive patches and ground plane. The AMC surface is designed to resonate at 2.45GHz with the goal to enhance the transmission between antennas. A small textile AMC waveguide sheet as well as an AMC waveguide jacket were fabricated. The S-parameters performance of the two antennas with textile AMC sheet was investigated in a free space environment and near to human body setting. The efiect of difierent antennas' orientations was also considered. Measurements were conducted thoroughly to validate the simulated flndings. Compared to free space environment, S21 transmission between two dipoles is improved up to maximum i10dB when having textile AMC waveguide sheet beneath them. For both ofi-body and on-body placements, signiflcant transmission enhancement has been observed with the introduction of the AMC sheet-like waveguide. Directive radiation patterns with high gain have also been achieved with the proposed AMC waveguide jacket.

Numerical and Experimental Analysis of Microstrip Antennas Loaded with a Single DNG Resonator

This paper deals with the numerical and experimental analysis of the effects of non-conventional materials on antenna performance. The paper is divided into two main sections: numerical simulations and experimental characterization. First, a microstrip antenna loaded with a Double-Negative (DNG) substrate is numerically simulated to study its effect on size and performance. Then the same antenna using conventional substrate is top loaded with a novel single-sided resonator (referred as diamond dipole resonator or DDR) showing DNG behavior. The antenna is manufactured and measurements are performed. The results show that the use of the DDR produces a dramatic 73.9% return loss improvement as well as a frequency shift. Issues about size reduction and negative refractive index effects are further presented and discussed.

Diamond dipole antenna for ultra-wideband communications

A diamond dipole antenna (DIDA) with rounded feeding edges for ultra-wideband (UWB) communications, optimized using the finite-difference time-domain (FDTD) technique is presented in this paper. The antenna has a bandwidth of 11.15 GHz (5.34:1) for a voltage standing wave ratio (VSWR) ≤ 2, while retaining good radiation pattern characteristics in this bandwidth. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 536–538, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21040

Wideband Dipoles on Electromagnetic Bandgap Ground Planes

The performance of broadband dipole antennas above electromagnetic bandgap (EBG) structures is investigated. Two different structures are examined. One is a diamond dipole over an EBG with square patch elements optimized by hand and the other an open sleeve dipole over an EBG optimized by a genetic algorithm (GA). Both configurations demonstrate that a low profile dipole antenna over an EBG can have a broad bandwidth. Careful design of both is required and in particular for best results, the antenna-EBG system should be optimized together, rather than as separate components. The performance is compared to an absorber backed wideband dipole antenna and it is found that the gain is significantly increased, whilst the bandwidth is reduced. In general, for the diamond dipole antenna return loss bandwidths of over 2:1 (67%) have been achieved, although radiation pattern control is difficult and reduces the bandwidth to the order of 1.4:1 (33%). The sleeve dipole over an EBG achieved a bandwidth of 1.28:1 (26%). The realized gain, which is power gain reduced by input match loss, of both structures are approximately the same. GA optimization and parametric studies seem to suggest that bandwidths significantly greater than these are difficult to achieve.