Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines.

Rf energy harvester

Two novel designs of planar elliptical slot antennas are presented. Printed on a dielectric substrate and fed by either microstrip line or coplanar waveguide with U-shaped tuning stub, the elliptical/circular slots have been demonstrated to exhibit an ultrawideband characteristic. The performances and characteristics of the proposed antennas are investigated both numerically and experimentally. Based on these analyses, an empirical formula is introduced to approximately determine the lower edge of the -10 dB operating bandwidth. It is also shown that these antennas are nearly omnidirectional over a majority fraction of the bandwidth.

Study of printed elliptical/circular slot antennas for ultrawideband applications

Basic principles for ultra-wide-band (UWB) radiation are presented and discussed in this paper. The discussion starts with a description of the influence of antennas on UWB transmission. The parameters characterizing antennas in time and in frequency domain are specified. Since the number of possible antenna structures is nearly unlimited, the focus will be on a classification according to different radiation principles. For each of these mechanisms, the typical advan- tages and disadvantages are discussed, and an example antenna and its characteristics are presented. For a wireless engineer, the problem to solve is the proper design of an antenna with the desired radiation characteristics. The final outcome of this paper is that there exist numbers of UWB antennas, but not each of them is suited for any application, especially in view of radar and communication systems requirements.

http://ieeexplore.ieee.org/iel5/5/4802183/04802200.pdf

Basic Properties and Design Principles of UWB Antennas Selection of suitable antennas from the many existing types, based on understanding their characteristics, is essential for effective ultrawide-band system design.

Basic principles for ultra-wide-band (UWB) radiation are presented and discussed in this paper. The discussion starts with a description of the influence of antennas on UWB transmission. The parameters characterizing antennas in time and in frequency domain are specified. Since the number of possible antenna structures is nearly unlimited, the focus will be on a classification according to different radiation principles. For each of these mechanisms, the typical advantages and disadvantages are discussed, and an example antenna and its characteristics are presented. For a wireless engineer, the problem to solve is the proper design of an antenna with the desired radiation characteristics. The final outcome of this paper is that there exist numbers of UWB antennas, but not each of them is suited for any application, especially in view of radar and communication systems requirements.

Basic Properties and Design Principles of UWB Antennas

A new compact planar ultrawideband (UWB) antenna designed for on-body communications is presented. The antenna is characterized in free space, on a homogeneous phantom modeling a human arm, and on a realistic high-resolution whole-body voxel model. In all configurations it demonstrates very satisfactory features for on-body propagation. The results are presented in terms of return loss, radiation pattern, efficiency, and E-field distribution. The antenna shows very good performance within the 3-11.2 GHz range, and therefore it might be used successfully for the 3.1-10.6 GHz IR-UWB systems. The simulation results for the return loss and radiation patterns are in good agreement with measurements. Finally, a time-domain analysis over the whole-body voxel model is performed for impulse radio applications, and transmission scenarios with several antennas placed on the body are analyzed and compared.

A Compact UWB Antenna for On-Body Applications

The paper presents a study of coplanar waveguide (CPW) fed circular disc monopole antenna for ultra-wideband (UWB) applications. A circular disc monopole printed on a dielectric substrate and fed by a 50 /spl Omega/ CPW on the same layer can yield an ultra-wide -10 dB return loss bandwidth with satisfactory radiation patterns. The performance and characteristics of the antenna are investigated in order to understand its operation. Good agreement has been obtained between the simulation and experiment.

http://ap-s.ei.tuat.ac.jp/isapx/2004/pdf/1B2_4.pdf

Study of CPW-fed circular disc monopole antenna for ultra wideband applications

This paper proposes and studies a novel design of a coplanar waveguide (CPW) fed circular disc monopole antenna for ultra wideband (UWB) applications. A circular disc monopole printed on a dielectric substrate and fed by a 50 /spl Omega/ CPW on the same layer is demonstrated numerically and experimentally to yield an ultra wide -10 dB bandwidth with omnidirectional radiation patterns over the entire bandwidth. The effect of the disc dimension on the antenna performance is also investigated.

CPW-fed circular disc monopole antenna for UWB applications

A novel and simple ultrawideband (UWB) printed quasi-self-complementary antenna is presented. The proposed antenna, which is fed by a microstrip line, has been demonstrated to provide an ultrawide 10-dB impedance bandwidth with satisfactory radiation properties. It also features both physically and electrically small dimensions, 16 mm times 25 mm in a physical size and 0.24lambda in an electrical size, respectively. The key parameters that affect the performance of the antenna are investigated. A good agreement is achieved between the simulation and the measurement.

A Small Printed Quasi-Self-Complementary Antenna for Ultrawideband Systems

A novel miniature antenna design for ultra-wideband (UWB) applications is presented. The proposed compact antenna is achieved by exploiting a quasi-self-complementary structure along with a tapered radiating slot. The optimal design of this type of antenna can offer an ultra-wide 10 dB impedance bandwidth with reasonable radiation properties. It also exhibits very small dimensions, 19×16 mm in physical size, and 0.19 λ in electrical size. Good agreement is obtained between simulated and measured antenna characteristics.

Study of compact antenna for UWB applications

A novel and simple design of a quasi-self-complementary antenna for ultra wideband applications is presented. The proposed antenna, which is fed by a 50 Ω coplanar waveguide without using a matching circuit, can offer an ultra-wide 10 dB impedance bandwidth. It also features a compact and small size, only 0.22 λ at 1.3 GHz, which is the lower end of the bandwidth. Good agreement is achieved between the simulation and the experiment.

Lu Guo

Papers

Study of CPW-fed circular disc monopole antenna for ultra wideband applications

CPW-fed circular disc monopole antenna for UWB applications

A Small Printed Quasi-Self-Complementary Antenna for Ultrawideband Systems

Study of compact antenna for UWB applications

Study of printed quasi-self-complementary antenna for ultra-wideband systems