Shengjian Jammy Chen

A Compact, Highly Efficient and Flexible Polymer Ultra-Wideband Antenna

A compact, highly efficient and flexible ultra-wideband antenna operating from 3 to 20 GHz is proposed in this letter. The antenna is completely made from polymer comprising a patterned conductive polymer (PEDOT) thin film attached to a transparent sticky tape substrate. The overall dimension is less than a quarter-wavelength at the lowest frequency of operation and the device reaches a radiation efficiency of over 85% averaged throughout the frequency band. The antenna performs well under various bending conditions as demonstrated by measurements. The realized antenna offers great mechanical flexibility and robustness which indicates its promising potential for possible seamless integration in flexible electronics.

Paired Snap-On Buttons Connections for Balanced Antennas in Wearable Systems

A pair of commercial snap-on buttons is demonstrated as a detachable radio frequency (RF) balanced connection between a garment-integrated textile dipole antenna and a passive sensor-enabled radio frequency identification (RFID) tag in a wearable wireless system. This arrangement offers reliable, low-cost, and easily detachable RF coupling and feeding connections for balanced antennas, as conceptualized in simulations and validated through measurements. In addition, a back-to-back balanced transmission-line structure has been designed and measured to characterize the RF performance of the proposed snap-on button connection. The resulting S-parameters indicate the good performance of the snap-on buttons as RF connectors for balanced antennas/transmission lines at least up to 5 GHz with insertion loss better than 0.8 dB.

A Modular Textile Antenna Design Using Snap-on Buttons for Wearable Applications

An antenna design concept with detachable radiation elements offering modular geometry reconfigurabilities for wearable applications is presented. By utilizing snap-on buttons, both as the radio-frequency (RF) connection and mechanical holding mechanism, different modularly interchangeable microstrip patches are employed to demonstrate geometry reconfigurabilities in terms of polarization and resonance frequency. The uniqueness of the design arises from the fact that all configurations share one common feed structure which consists of a two-layered substrate including snap-on buttons, a ground plane, and a proximity coupled feed. To show the concept, modular realizations with different functionalities in terms of polarization or resonance frequency are demonstrated in this paper. First, a detachable patch offering interchangeable right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) at 5 GHz is proposed. Second, a demonstration of a planar inverted-F antenna (PIFA) concept offering interchangeable resonance frequencies for the 2.4- and 5.3-GHz bands of wireless local area networks (WLAN) is given. Finally, a patch module designed for 8-GHz operation is presented to show the versatility in frequency modularity. Experimental results of the fabricated antennas in freeAn antenna design concept with detachable radiation elements offering modular geometry reconfigurabilities for wearable applications is presented. By utilizing snap-on buttons, both as the radio-frequency (RF) connection and mechanical holding mechanism, different modularly interchangeable microstrip patches are employed to demonstrate geometry reconfigurabilities in terms of polarization and resonance frequency. The uniqueness of the design arises from the fact that all configurations share one common feed structure which consists of a two-layered substrate including snap-on buttons, a ground plane, and a proximity coupled feed. To show the concept, modular realizations with different functionalities in terms of polarization or resonance frequency are demonstrated in this paper. First, a detachable patch offering interchangeable right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) at 5 GHz is proposed. Second, a demonstration of a planar inverted-F antenna (PIFA) concept offering interchangeable resonance frequencies for the 2.4- and 5.3-GHz bands of wireless local area networks (WLAN) is given. Finally, a patch module designed for 8-GHz operation is presented to show the versatility in frequency modularity. Experimental results of the fabricated antennas in free space, worn by a torso phantom and in bending conditions, validate the concept and prove that this type of modular design offers convenient, passive, low cost, and versatile system reconfigurabilities, which can benefit wearable applications. space, worn by a torso phantom and in bending conditions, validate the concept and prove that this type of modular design offers convenient, passive, low cost, and versatile system reconfigurabilities, which can benefit wearable applications.

Scalable realization of conductive graphene films for high-efficiency microwave antennas

A fabricated antenna based on highly conductive graphene films is demonstrated with an efficiency averaging 79% over a bandwidth from 3.1 to 10.6 GHz. This is the highest reported value for graphene antennas in the microwave region due to the combination of high conductivity, substantial thickness and efficiency-driven antenna design.

Shorting strategies for a wearable L-slot planar inverted-F antenna

Wearable antennas are one of the key technologies supporting wearable wireless communication systems. A wearable textile L-slot planar inverted-F antenna is investigated in this paper with different shorting methods, namely a folded strip of silver fabric, embroidered vias and eyelets. The performance of the proposed antenna with these three shorting methods is compared through simulations with realistic shorting models. According to the obtained numerical results, the antenna has three resonances at 4.5 GHz, 5.0 GHz and 6.6 GHz. In terms of gain and efficiency, the embroidered vias shorting method, which is the simplest and cheapest method to implement, has slightly lower performance than the silver fabric folded strip and eyelet shorting methods due to its higher resistance.

Wearable textile microstrip patch antenna for multiple ISM band communications

A wearable probe-fed microstrip antenna manufactured from conductive textile fabric designed for multiple Industrial-Scientific-Medical (ISM) band communications is presented in this paper. The proposed antenna operating at 2.450 GHz, 4.725 Hz and 5.800 GHz consists of a patch and ground plane made of silver fabric mounted on a substrate of flexible low-permittivity foam. For verification, a reference prototype is manufactured from copper. The measurement of both antennas demonstrates the expected resonances, with some unexpected loss especially in the higher frequency range. Simulation results for the antenna in various bending condition indicate the robustness of the design with deviations of resonant frequencies in an acceptable range.

A foldable textile patch for modular snap-on-button-based wearable antennas

A concept of modular textile antenna design with commercial snap-on buttons has been proposed recently for wearable applications. The concept was shown to provide passive system reconfigurabilities in regard to resonance frequency and polarization without modifications to the feeding structure. As an extension of this work, a foldable patch module is presented in this paper for the antenna concept, demonstrating further passive discrete resonance frequency modularity at 8, 9 and 10 GHz. Through a simple folding of the textile radiating element at predetermined lengths denoted by position markers, particular resonance frequencies can be manually interchanged. Prototype-based experimental characterization shows a good agreement with simulations, which indicates that the foldable module performs as expected. This design emphasizes that the reported modular antenna design promotes a practical, low-manufacture-cost, low-maintenance-cost, passive and versatile solution to reconfigure system characteristics for multi-functional wearable systems.

A 5.8-GHz flexible microstrip-fed slot antenna realized in PEDOT:PSS conductive polymer

A flexible 5.8-GHz microstrip-fed slot antenna realized in thin films of conductive polymer PEDOT:PSS is presented. As a result of the highly conductive and flexible polymeric film utilization, the antenna has a high efficiency of 82% and fully reversible conformability. A PEDOT and a reference copper antenna prototypes have been fabricated and experimentally characterized. The good agreement between simulations and measurements suggests that conductive polymers are a promising class of non-metallic conducting materials for antenna engineering, particularly for conformal designs.

Progress in conductive polymer antennas based on free-standing polypyrrole and PEDOT: PSS

In this paper, various realizations of microwave antennas based on free-standing conductive polymers including polypyrrole (PPy) and PEDOT:PSS (PEDOT) are reviewed in regard to two significant aspects: improvement of their efficiency and exploitation of their mechanical flexibility for antenna designs. On the one hand, with strategies such as simple chemical material treatments, deployment of non-resonant antenna structure and multilayer configurations, very high antenna efficiencies can be achieved. On the other hand, through the utilization of the conductive polymers and flexible, robust and low-loss substrates, reproducible antenna mechanical conformability can be achieved. All these facts suggest that conductive polymers are promising as conductor materials for flexible and wearable antenna designs.

Snap-on buttons as detachable shorting vias for wearable textile antennas

This paper demonstrates that commercial snap-on buttons can be utilized as detachable shorting vias for wearable textile antennas. As a consequence, modularity in antenna characteristics can be obtained based on a common initial design. As an illustration, a patch antenna with different configurations of shorting vias is designed and experimentally characterized. In this design, adapted from a recently reported modular snap-on-button-based wearable antenna, four sets of two back-to-back male snap-on buttons affixed within a two-layered substrate are used as detachable patch holders and/or modular shorting vias to the ground plane. By engaging selected male buttons from the ground plane with female buttons to form shorting vias, various antenna patterns can be selected.