RFID 2013
Parametric analysis and design guidelines of RF-to-DC Dickson charge pumps for RFID energy harvesting (Paper)This paper presents the effects of design parameters on output efficiency and input impedance of RF-to-DC Dickson charge pumps by varying input parameters in simulation. Diode parasitics and input impedance mismatch between the charge pump and antenna are found to significantly decrease the effectiveness of charge pumps, while stage capacitance size appears to have little effect on efficiency. Off-the-shelf diodes are also compared through simulation to find which diodes perform best at each ISM frequency band and various power levels. The investigation is summarized by guidelines to assist designers in developing efficient RF-to-DC Dickson charge pumps as well as concluding with a design methodology.
RFID 2013
Staggered Pattern Charge Collection: Antenna Technique to Improve RF Energy Harvesting (Paper)
This paper introduces the theory of N-by-N staggered pattern charge collectors (SPCC) and a methodology to design and optimize SPCCs for maximum energy harvesting efficiency. The SPCC uses multiple sub-arrays to form an aggregate gain pattern for harvesting RF wireless energy more efficiently than a single antenna or a collection of antennas occupying a similar footprint when the transmitter location is unknown.
This paper introduces the theory of N-by-N staggered pattern charge collectors (SPCC) and a methodology to design and optimize SPCCs for maximum energy harvesting efficiency. The SPCC uses multiple sub-arrays to form an aggregate gain pattern for harvesting RF wireless energy more efficiently than a single antenna or a collection of antennas occupying a similar footprint when the transmitter location is unknown.
Wireless Power Transfer 2013
DC Power Pattern Analysis of N-by-N Staggered Pattern Charge Collector and N2 Rectenna Array (Paper)
This paper compares a 4-by-4 dipole staggered pattern charge collector (SPCC) rectenna array to a 16 dipole rectenna array arranged in a four series-four parallel configuration. While each of these energy harvesting circuits has an identical footprint, the SPCC has a DC power pattern which simultaneously provides high gain and wide beamwidth. This profile provides RF energy harvesting sensors with additional range and makes them less sensitivity to orientation. At 0.1 m range, the N2 rectenna has a peak DC voltage 20% larger than the SPCC, but the SPCC’s beamwidth is 400% larger than the N2 rectenna array. At 1 m range, the SPCC beamwidth is 600% larger, and the peak voltage is 300% larger than the N2 rectenna control case.
This paper compares a 4-by-4 dipole staggered pattern charge collector (SPCC) rectenna array to a 16 dipole rectenna array arranged in a four series-four parallel configuration. While each of these energy harvesting circuits has an identical footprint, the SPCC has a DC power pattern which simultaneously provides high gain and wide beamwidth. This profile provides RF energy harvesting sensors with additional range and makes them less sensitivity to orientation. At 0.1 m range, the N2 rectenna has a peak DC voltage 20% larger than the SPCC, but the SPCC’s beamwidth is 400% larger than the N2 rectenna array. At 1 m range, the SPCC beamwidth is 600% larger, and the peak voltage is 300% larger than the N2 rectenna control case.
Radio Wireless Week 2013
Staggered Pattern Charge Collector Design and Optimization (Best Student Paper Finalist)
This paper outlines an innovative antenna configuration called a staggered pattern charge collector (SPCC) to increase microwave wireless energy harvested from an antenna at 5.8 GHz. The two-by-two staggered pattern charge collector (SPCC) uses a pair of two-element linear arrays to increase gain and effective aggregate “beamwidth” to capture more wireless energy than a single patch antenna. Also, a new array parameter called integrated power conversion gain (IPCG) is introduced as a metric to compare how effective antenna systems are at energy harvesting. Finally, the SPCC is optimized to maximize IPCG and the optimized, fabricated SPCC’s DC voltage output data is measured. (Poster) (Presentation)
This paper outlines an innovative antenna configuration called a staggered pattern charge collector (SPCC) to increase microwave wireless energy harvested from an antenna at 5.8 GHz. The two-by-two staggered pattern charge collector (SPCC) uses a pair of two-element linear arrays to increase gain and effective aggregate “beamwidth” to capture more wireless energy than a single patch antenna. Also, a new array parameter called integrated power conversion gain (IPCG) is introduced as a metric to compare how effective antenna systems are at energy harvesting. Finally, the SPCC is optimized to maximize IPCG and the optimized, fabricated SPCC’s DC voltage output data is measured. (Poster) (Presentation)
Pediatric Surgery and Technology Research Day 2012 at Emory University
Electromagnetic Field Analysis of Near Body Wireless Technologies (Poster)
Today, wireless communication is more integrated into our daily life than ever before and wireless signals are transmitted from electronics in close proximity to our bodies. At high power levels, radiated wireless signals can be detrimental to the human body. This presentation focuses on the varying power densities of different wireless technologies near the human body during operation including WiFi, cellular phones, Bluetooth, and RFID. Smarter transmitters and backscatter systems can dramatically reduce the power density of wireless signals for many applications such as incontinence monitoring on children.
Today, wireless communication is more integrated into our daily life than ever before and wireless signals are transmitted from electronics in close proximity to our bodies. At high power levels, radiated wireless signals can be detrimental to the human body. This presentation focuses on the varying power densities of different wireless technologies near the human body during operation including WiFi, cellular phones, Bluetooth, and RFID. Smarter transmitters and backscatter systems can dramatically reduce the power density of wireless signals for many applications such as incontinence monitoring on children.
RFID 2012
Multi-antenna techniques for enabling passive RFID tags and sensors at microwave frequencies (Paper)
Multi-antenna techniques are typically avoided in passive RFID because of the large footprints required. However, the smaller footprints required at microwave frequencies such as the 5.8 GHz industrial, scientific, and medical (ISM) band allow the use of multiple antennas. Two new multi-antenna technologies are featured in this paper to provide power and communications to a passive wireless tag in the 5.8 GHz ISM band. A four-layer FR-4 PCB is presented, which uses a staggered-pattern charge collector (SPCC) and a retrodirective array phase modulator (RAPM). An SPCC is an energy harvester that has two independent antenna arrays. These arrays provide increased gain and beamwidth over a single-antenna source. A RAPM backscatters the reader-transmitted signal directly back to the reader and provides quadrature phase-shift keyed (QPSK) signaling.
Multi-antenna techniques are typically avoided in passive RFID because of the large footprints required. However, the smaller footprints required at microwave frequencies such as the 5.8 GHz industrial, scientific, and medical (ISM) band allow the use of multiple antennas. Two new multi-antenna technologies are featured in this paper to provide power and communications to a passive wireless tag in the 5.8 GHz ISM band. A four-layer FR-4 PCB is presented, which uses a staggered-pattern charge collector (SPCC) and a retrodirective array phase modulator (RAPM). An SPCC is an energy harvester that has two independent antenna arrays. These arrays provide increased gain and beamwidth over a single-antenna source. A RAPM backscatters the reader-transmitted signal directly back to the reader and provides quadrature phase-shift keyed (QPSK) signaling.