John C. Batchelor

Cylindrical Slot FSS Configuration for Beam-Switching Applications

A novel design for a beam-switching antenna using active cylindrical slot frequency selective surface (ACSFSS) is presented. The antenna system is composed of an omnidirectional monopole antenna and the ACSFSS, which employs a new technique of switching slot arrays. The ACSFSS is made up of 12 columns with 8 slots each, dividing the cylinder by 30°. To steer the beam of the antenna the diodes are set off and on, so that the radiation pattern of the antenna is determined by the number of off state columns. To estimate the general dimension of the cylindrical FSS, an equivalent metallic reflector is introduced and optimized, and then parametric studies for the unit cell dimensions are discussed. The fabricated prototype works within the WLAN band, centered around 2.45 GHz, and can agilely select either a narrow-beam or wide-beam operating mode. Simulation and measurements confirm the operation of the ACSFSS antenna, with good matching and gain observed. In particular, the narrow-beam mode -3 dB beamwidth is 47° which offers enhanced angular resolution compared with other reported beam-sweeping work.

Design of low-cost multimode fiber-fed indoor wireless networks

A low-cost option for transporting global system for mobile communication, Universal Mobile Telecommunication System and wideband local area network (WLAN) signals using multimode fiber (MMF) with 850-nm vertical-cavity surface-emitting lasers (VCSELs) is investigated through range predictions from a link budget analysis. These predictions are experimentally verified for WLAN signal transmission in an office environment, using a commercial access point and a 300-m (OM1/OM2) MMF link with low-cost 850-nm VCSEL transmitters. The analysis indicates that good performance and signal coverage is possible with optimum design of indoor fiber-fed wireless systems, even when using such inexpensive components

Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis

The paper presents a new concept in antenna design, whereby a photo-imageable thick-film process is used to integrate a waveguide antenna within a multilayer structure. This has yielded a very compact, high performance antenna working at high millimeter-wave (mm-wave) frequencies, with a high degree of repeatability and reliability in antenna construction. Theoretical and experimental results for 70 GHz mm-wave integrated antennas, fabricated using the new technique, are presented. The antennas were formed from miniature slotted waveguide arrays using up to 18 layers of photo-imageable material. To enhance the electrical performance a novel folded waveguide array was also investigated. The fabrication process is analyzed in detail and the critical issues involved in the fabrication cycle are discussed. The losses in the substrate integrated waveguide have been calculated. The performance of the new integrated antenna is compared to conventional metallic, air-filled waveguide antennas, and also to conventional microstrip antenna arrays operating at the same frequencies.

Singly and Dual Polarized Convoluted Frequency Selective Structures

Convoluting the elements of frequency selective surfaces produces resonating structures with very small unit cell dimensions. This feature is attractive when the FSS is to be used at low frequencies, mounted on a curved surface, or when placed in the proximity of compact radiators. The characteristics of single and dual polarized convoluted FSS are analyzed and measured. The development of novel convoluted elements derived from the square loop slot is traced and their performance is examined. A novel technique of interweaving convoluted loops allows for further cell size reduction, while increasing the passband width, introducing flexibility in wideband FSS design, particularly for tailoring the electromagnetic architecture of buildings, and mobile communications in the built environment. Simulated transmission responses of the convoluted structures are in good agreement with the measurements.

Dual-Band Tunable Screen Using Complementary Split Ring Resonators

Active frequency selective surfaces (FSS) based on slot-form split ring resonators are described. Switching and tuning have been achieved using two different biasing circuit configurations. The first design switches ON and OFF the two concentric rings separately, producing four distinct transmission responses. The second design is able to vary the capacitance of the two split rings, allowing independent dual-band frequency tuning. The active FSS incorporate commercially available, low cost, surface mount switched PIN diodes and varactor diodes. The operation of the surfaces covers a wide band frequency range within the UHF spectrum, which is desirable for applications such as the modification of the EM architecture of buildings. Measurements compare well with the simulations.

An Active Annular Ring Frequency Selective Surface

Offering good performance in terms of all polarizations affected and good angular stability, the ring element is a popular choice in frequency selective surface (FSS) designs. This paper introduces a topology for two-state switching of a ring based FSS. The two states offered by the surface enable it to be either transparent or reflective at the frequency of interest. A design targeted at the 2.45 GHz WLAN band, and intended for the control of the electromagnetic architecture of buildings (EAoB), is realized both by simulation and measurement, the results of which are presented and evaluated.

Temporary On-Skin Passive UHF RFID Transfer Tag

A passive UHF RFID tag design is presented in the form of a transfer patch similar to a temporary tattoo that is mountable directly onto the skin surface. The transfer tag is suitable for monitoring of people over time in mission critical and secure environments. The antenna reactance is first calculated to conjugate match the measured RFID chip reactance and then full wave simulation is used to design the tag with good performance on a human flesh model. Finally the tag read range is measured on different parts of a volunteers body and compared to simulated read range values for the entire RFID bands.

Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags: the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique

Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices demonstrate performances which achieve wireless communication requirements having a forward transmission scattering parameter, S21, depth greater than -20 dB at 13 GHz. Printed and plasma sintered RFID tags on transfer paper, which are capable of being mounted on skin, improved read distances compared to previously reported single layer transfer RFID tags fabricated by conventional thermal sintering. This journal is cop. The Royal Society of Chemistry 2015.

Single and double layer planar multiband PIFAs

A compact multiband planar inverted-F antenna (PIFA) suitable for distributed radio-over-fiber repeater networks is modified into a planar structure. It is shown that the planar antenna performance is not degraded with respect to the original PIFA and further, a two layer design is demonstrated to offer improved feed matching. The European bands for GSM, DCS-1800, DECT, UMTS, Bluetooth and HiperLAN2 are all covered. A model of the antenna is introduced as a first stage to developing an equivalent circuit

UWB wearable button antenna

A UWB antenna based on button structures will be presented in this paper. The antennas use the wearable metallic button features and its bandwidth characteristics to create body-centric UWB monopole antennas. The antenna resulted is a rigid wearable antenna structure which is able to operate within the 3.1 GHz to 10.6 GHz bandwidth required for UWB communication systems. Good omni-directional pattern were obtained for the antenna which is desirable for transmission with other wearable devices located across the body.