A compact wideband helix antenna for wireless meat probe with highly efficient RF energy harvesting Shaoyong Wang Appliances TE Connectivity Shanghai, China
[email protected] Abstract— A meat probe can be used to help end users to get customized and precise roasting of meat, fish and poultry by monitoring the core temperature. Conventional meat probe applied in an oven uses a wire to connect the probe with the oven. Recently, the market requires a meat probe with the same size as conventional one but be wireless and battery-less for more utility freedom, better water and oil proof, easy clean and maintenance-free. This paper describes the design procedure as well as the experimental performance of a wideband helix antenna which covers both 868MHz and 915MHz bands for a wireless meat probe to harvest RF energy with high efficiency. The helix antenna has a circular patch in the bottom to enhance its bandwidth and reuses the metal cylinder of the meat probe as RF choke to reduce the adverse impact caused by the variation of food parameters during cooking. Simulation results show that the helix antenna has return losses better than 8dB and antenna efficiency higher than 70% when the meat probe is inserted to a piece of meat during cooking. The experiment results show that wireless meat probe using the antenna has better stability in measuring food temperature than conventional helix antenna.
Yuming Song Appliances TE Connectivity Shanghai, China
[email protected] II. DESIGN OF ANTENNA AND SLEEVE BALUN A. Design of helix antenna As shown in figure 1, the main body of the wireless meat probe consists of a handle and a metal cylinder. The helix antenna is placed inside of the handle and connected with the RF-DC chipset on the PCB through a length of coaxial cable. Because the space in the handle is very limited for a helix antenna, the length of the helix is chosen to be quarter wavelength with pitch of 2mm. A circular metal patch of 5mm radius is placed at the bottom of the helix to increase the operation bandwidth of antenna.
Keywords— energy harvesting, wireless power, helix antenna, RF choke
I.
INTRODUCTION
With the increased interest in energy harvesting in recent years and the ever-increasing use of ultra-low power microcontrollers and sensors in internet-of-things, there has been a significant interest in designing energy harvester of compact size and high performance. For the application in harsh environment, RF energy harvesting can supply stable wireless power comparing with other energy forms such as mechanical or thermal energy. The harvester antenna plays a very important role in RF energy harvesting performance. However, its design is challenging when its overall size is compact (
