Showing papers on "Coaxial antenna published in 2019"

Helical Slot Antenna for the Microwave Ablation

Abstract: In this study, a thin coaxial antenna for microwave ablation (MWA) is proposed. A helical slot is added between two slots in order to overcome the disadvantage of the radiation range extending to the unwanted part in the conventional single-slot and double-slot applicators. By adding a helical slot, the specific absorption rate (SAR) pattern is more concentrated near the slot as compared with the conventional slot. Experiments were conducted using the simulation, and a liver phantom was made and heated up using microwaves. Based on the results on the liver phantom, experiments were conducted using swine liver which is similar to human liver. Applied frequency and microwave average input power were assumed as 2.45 GHz and 50 W (47 dBm), respectively. As a result of the experiment, return loss was −23.09 dB, and the temperature reached 60°C after 90 seconds of exposition. Based on the phantom experiments of the swine liver, necrotic lesions of the tissue at a distance of 3.5–4 cm from the microwave antenna were observed.

Multi-micro wave source heating system

Abstract: The invention discloses a multi-micro wave source heating system. The multi-micro wave source heating system comprises a microwave furnace cavity and a furnace door, wherein a solid-state source and amagnetron are arranged in the microwave furnace cavity, the solid-state source is connected with an electric tunable radio-frequency coaxial antenna, the magnetron is connected with a microwave waveguide exciter, and the solid-state source and the magnetron are used as microwave sources to jointly heat. By the multi-micro wave source heating system, various microwave sources can be used for jointly heating, and the microwave heating efficiency is improved.

Investigation of Influence of Coaxial Antenna Slot Positioning on Thermal Efficiency in Microwave Ablation using COMSOL

Abstract: Continued development of the minimum invasive interventional technology in recent years has proven ablation therapy to be a safe and effective local treatment for cancers and has become increasingly important in the medicine. This is the reason for its preference for treating larger tumors than for radiofrequency ablation. The authors studied the influence of the geometry of the antenna used on the efficiency of the procedure to obtain a thermal lesion at the site of the tumor. The influence of the position of the coaxial antenna on the extent of the thermal lesion at the site of the tumor was investigated numerically by varying the distance from the position of the end of the antenna with COMSOL Multiphysics as the modeling tool. The coaxial antenna investigated has a 1.79 mm diameter range with a center conductor of 0.29 mm diameter and Tefzel ETFE as the material of the catheter. The power of the coaxial antenna was optimized with a slot spacing of 6 mm from the tip of the antenna. The total power dissipation density, and thus the degree of thermal damage generated during the process was found to depend on the position of the slots of the coaxial antenna.

Coaxial Antenna Slot Impact On Thermal Effectiveness In Microwave Ablation Therapy

Abstract: Ablation is a minimally invasive procedure used in the treatment of small tumours. Tumour sizes of about 3 cm are now been effectively treated with thermal ablation therapy using either microwave ablation or radiofrequency ablation. The impact of the slot position on a coaxial antenna on the extent of thermal lesion at the tumour site was investigated numerically in this study by varying the slot distance from the antenna tip using COMSOL Multiphysics as the modelling tool. The coaxial antenna size investigated has a diameter of 1.79 mm, with a central conductor diameter of 0.29 mm and Tefzel ETFE as the catheter material. The coaxial antenna performance was optimized at a slot distance of 6 mm from the antenna tip. The total power dissipation density and hence, the degree of thermal lesion created during the procedure is dependent on slot position of the coaxial antenna.

Single Slot Coaxial Antenna and NiTi (Nickel Titanium) Loop Antenna Design for ISM (Industrial Scientific Medical) Band Microwave Ablation System

Abstract: For MWA applications in the ISM band, the bioimplant single slot coaxial antenna and NiTi ring antenna are designed. The characteristics of the Sucoform_86 / coaxial cable used in the design of the single slot coaxial antenna are given. Simulation and measurement results of return loss, input impedance, gain, VSWR of the designed bioimplant single slot coaxial antenna are examined. Tumor ablation simulation configuration used, SAR (f = 2.45 GHz) (1gr) simulation result, cut plane image of antenna, curve and multilayered tissues (skin, fat, muscle, tumor), obtained along the curve using heat sources of different strengths Length (mm) - Temperature (Kelvin) graph and Length (mm) - Electric Field (V / m) graph obtained along the curve are presented. The electrical properties of NiTi material have been measured and presented. The return loss, electrical field and orientation parameters of the designed NiTi ring antenna were analyzed and CST drawing of NiTi ring antenna, return loss measurement mechanism and measurement result were presented.

Antenna device and method for manufacturing same

Abstract: Provided is an antenna device having a structure that suppresses deterioration in performance as a profile becomes lower. Four FM band antenna elements and two AM band antenna elements are arranged side by side on an antenna base. Further, a circuit board including synthesis circuits in one-to-one correspondence with the antenna elements, respectively, is arranged in an inner space of the antenna elements. In order that omnidirectionality may be exhibited in a horizontal plane, each of the antenna elements includes a helically wound linear conductor, and a planar conductor that is electrically connected to the linear conductor at a part substantially the farthest from a ground plane (antenna base.

Small microwave oven adopting 900MHz solid-state source power amplifier as microwave source

Abstract: The utility model discloses a small microwave oven adopting a 900MHz solid-state source power amplifier as a microwave source. The microwave oven comprises a microwave oven cavity and an oven door, the microwave oven cavity is provided with a solid-state microwave source power amplifier and an electrically tunable radio frequency coaxial antenna. The solid-state microwave source power amplifier isconnected with the electrically tunable radio frequency coaxial antenna through a radio frequency transmission cable. The solid-state microwave source power amplifier and the electrically tunable radio frequency coaxial antenna are arranged on the outer side of the microwave oven cavity, and microwave heating of ISM low-frequency 900MHz frequency band in the miniature cavity can be realized by the aid of the miniature microwave oven with the 900MHz solid-state source power amplifier serving as the microwave source.

Dielectric-loaded 5.8 GHz Interstitial Monopole Antenna for Spherically-shaped Hepatic Tumors Ablation

Abstract: This paper introduces a modification of a coaxial interstitial monopole antenna for microwave hepatic cancer ablation. The proposed antenna achieves heating pattern look like a sphere at operating frequency of 5.8 GHz which is suitable for the hepatic tumors shaped The proposed coaxial antenna is loaded with higher dielectric constant material at the tip to act as an intermediate stage between the dielectric constant of the coaxial antenna and that of the liver tissue. This improves the impedance matching between the antenna and the liver tissues which in turn improves the matching between the antenna and generator. The dielectric constants of the antenna, the tip and the liver tissue are 2.03, 11 and 43.03, respectively. The antenna is simulated using COMSOL multiphysics simulator inside a modeled liver tissues cylinder at insertion depth of 50 mm for 10 minutes. The antenna has wider heating area than the conventional monopole. The simulation results show our proposed antenna has good performance.

Circularly polarized microstrip patch antenna

Abstract: The circularly polarized microstrip patch antenna comprises a conductive grounding plane, a dielectric substrate arranged on the conductive grounding plane, a radiation sheet arranged at the top of the dielectric substrate and a plurality of feed probes arranged on the peripheral side walls of the dielectric substrate, the dielectric substrate comprises a lower-layer high dielectric constant dielectric substrate and an upper-layer low dielectric constant dielectric substrate; the radiation sheet is a sheet-shaped circular metal conductor, and a gear-shaped opening with a symmetrical structureis machined in the middle of the radiation sheet. According to the utility model, a gradual change folding type side edge coupling feeding mode is adopted, the feeding probe is gradually bent, the processing is simple, a wide bandwidth is easy to form, the antenna circular polarization performance is improved, the phase center is stable, right-handed rotation and left-handed rotation circular polarization can be realized at the same time, and the antenna is especially suitable for accurate measurement and guidance system terminal equipment; two dielectric substrates with different dielectric constants are adopted, and the designed product is small in size, light in weight and wide in gain bandwidth, and can reach more than 25%.

Multi-structure antenna for multiband operation

Abstract: A wireless device operates in multiple frequency bands via a multi-structure arrangement that optimizes the electromagnetic performance at each frequency range of operation. The device includes a radiating system comprising a ground plane layer, a multi-structure antenna system that comprises at least two structural branches and at least a radiation booster, and a radiofrequency system. The radiofrequency system comprises an element inserted in the branch structure, connected at a point within the structure. The radiofrequency system may include an additional matching network that fine tunes the impedance of the device to match all the frequency ranges of operation.

Broadband dual-polarized antenna

Abstract: The invention discloses a broadband dual-polarized antenna. According to the broadband dual-polarized antenna, a radiating unit comprises four dipoles, and the four dipoles are combined and then installed on a reflecting plate; two arms of each dipole are respectively connected to the top ends of two supporting conductors, and the bottom ends of the supporting conductors are connected with a common base; the top ends of the two supporting conductors are separated by notch grooves, one of the conductors is provided with a longitudinal groove and a transverse groove, each longitudinal groove isprovided with a separation conductor, the separation conductors are adjacent to the notch grooves, and each transverse groove separates the separation conductor from the common base; four wires of thefour dipoles are respectively connected with the tail ends of the bottom portions of the corresponding separation conductors; additional conductors are placed on the arms of the dipoles; the tail ends of the additional conductors are bent towards the arms of the dipoles and are separated from end faces of the arms of the dipoles by dielectric films. The antenna can achieve half-power wave beam width with 60-65 degrees, the relative operation width with about 46% and cross polarization covering the edge of the fan in a range from -60 degrees to 60 degrees, and the matching and the compatibility in the wide frequency band range are good.

Intracavitary Microwave Hyperthermia Applicator with Resistive Coating for Targeted Heat Delivery

Abstract: Targeted heating and minimum invasiveness are desired characteristics for interstitial or intracavitary hyperthermia and ablation applicators Coaxial monopole wire antennas provide minimum invasiveness, but the current induced on the outer conductor radiates backwards and extends the heating zone beyond the antenna active zone Coaxial BALUN is widely used for choking the back current at the cost of increased applicator size and invasiveness in the tissue In this paper, we investigate the scope of resistive coating on the outer conductor of a 915 MHz monopole antenna proposed for hyperthermia treatment Numerical simulations are presented for a conventional coaxial monopole with and without a thin coating of PEDOT:PSS to study the influence of the resistive coating on suppressing the current induced on the outer conductor and tissue specific absorption rate (SAR) for varying antenna insertion depth in the tissue

A Coaxial Tri-slot Antenna with Aperiodic Layout of the Slots for Microwave Ablation

Abstract: Microwave ablation is a promising thermal therapy that is used to kill tumors by the high temperature. In clinical setting, an ablation zone with high sphericity is desirable because most tumors are nearly spherical shapes. In this study, a tri-slot coaxial antenna with aperiodic layout of the slots is proposed to achieve an ablation zone with high circularity. The genetic algorithm is used to optimize the layout of the slots. A FEM model is built for evaluate the performance of the proposed antenna. The simulation results show that the aperiodic tri-slot antenna can obtain a relatively small ablation zone with high sphericity.

Reflector antenna and reflector antenna feed

Abstract: Embodiments of the present invention provide a reflector antenna and a reflector antenna feed. The reflector antenna feed includes a transmit antenna array and a receive antenna array, where the transmit antenna array includes at least two transmit antenna units. The receive antenna array includes at least two receive antenna units. Also, a phase center of the transmit antenna array coincides with that of the receive antenna array, where at least one coupling unit is disposed between at least one group of a transmit antenna unit and a receive antenna unit that are adjacent to each other.

Wireless personal acoustic device with remote coaxial antenna

Abstract: Described is a personal acoustic device that includes at least one earphone, such as an earbud, and a radio frequency (RF) antenna module in electrical communication with a wireless transceiver module inside the earphone to support wireless communication between the device and a remote wireless device. The RF antenna module includes an antenna element disposed in or on a remote housing and further includes an RF coaxial cable having one end in electrical communication with the antenna element and an opposite end in communication with the wireless transceiver module. Improved transmission and reception performance are achieved through increased separation of the antenna module from a user's head and body as compared to an antenna element disposed in the earphone. In addition, the size of the earphone can be reduced relative to an earphone having an antenna element.

Simulation Results of 2.45 GHz Coaxial Antenna with a Ring Slot for Microwave Ablation of a Cancer

Abstract: Nowadays cancer is one of the leading causes of morbidity and mortality worldwide. Microwave ablation, as minimally invasive procedure, plays an increasingly important role in the treatment of cancer. In this thermal therapy, microwave energy delivery to a cancer tissue is enabled by electric fields radiated by interstitial antenna operating at microwave frequency. In this study, microwave ablation is numerically evaluated in the context of a liver cancer treatment using 2.45 GHz coaxial antenna with a ring slot. In order to design this antenna prototype and analyze its performance, simulations based on finite element method were done with the COMSOL Multiphysics software. In silico ablation experiments with the proposed antenna were performed using 10 W, 30 W and 50 W input microwave powers and different ablation times. Numerical results showed that the proposed ablation antenna has the ability to achieve a thermal lesion with a preferably spherical shape and clinically relevant volume with a maximum diameter of 3.5 cm using 30 W input microwave power during 10 minutes.

Modal separation method of vortex electromagnetic wave based on parallel non-coaxial antenna array UCA (uniform circular antenna)

Abstract: The invention discloses a modal separation method of vortex electromagnetic wave based on a parallel non-coaxial antenna array UCA (uniform circular antenna), and relates to the technical field of thewireless communication. The method comprises the following steps: solving hmn by utilizing a formula as shown in description, setting a received by the m-th antenna array on a receiving panel as ym,performing transform processing on the ym to obtain ym,10, obtaining y10 according to ym,10, thereby realizing modal separation on the vortex electromagnetic wave under the condition that a transmitting panel and the receiving panel are not strictly aligned. The defect that the modal separation cannot be performed on the vortex electromagnetic wave since the transmitting panel and the receiving panel are not strictly aligned in the prior art is solved.

Maximum likelihood detection method for vortex electromagnetic waves based on coaxial antenna array UCA

Abstract: The invention discloses a maximum likelihood detection method for vortex electromagnetic waves based on a coaxial antenna array UCA, and relates to the technical field of wireless communication. The maximum likelihood detection method is characterized in that hmn is solved according to a formula defined in the description, diagonalization is carried out on a channel matrix H formed by hmn according to a formula W*HW=[Lambda], y is set to be the sum of Hx and z, a received signal is processed according to a formula W*y=W*HWs+W*z=[Lambda]s+W*z, and estimation is performed on an information symbol vector, thereby realizing fast maximum likelihood detection for the vortex electromagnetic waves based on the coaxial antenna array UCA, and solving a defect that maximum likelihood detection cannotbe quickly and effectively carried out on the vortex electromagnetic waves based on the coaxial antenna array in the prior art.

Соленоїдна антена радіотехнічної системи ідентифікації металів

Abstract: The detection of metallic objects hidden in a dielectric medium is carried out with the aid of metal detectors constructed on a vortical current principle. Then detected metal is identified. For identification of metals, as usual, chemical, optoelectric, X-ray methods are used. But detection and identification can be done simultaneously using the graphic-digital image method. In such devices a coaxial solenoid antenna of the frame type is used. But it has low sensitivity, uneven depth sensitivity and a significant parasitic connection between the receiving and transmitting antennas. From such shortcomings, a free antenna is a DD type system, but it does not allow the use of a graphical-digital signal processing method. Therefore, a new design of the antenna system is proposed, which allows us to take advantage of the considered signal processing method and DD antennas. It is characterized in that one of the antennas, for example, a transmitter, consists of two parts that are symmetrically placed relative to the second and creates two active radiation zones, such as a coaxial antenna, but are similar to the radiation zones of the DD type antenna.

Portable wireless communication device

Abstract: A portable wireless access point (WAP) device 1 has a waterproof housing 2, a battery 25, and at least one coaxial antenna 10 with a gain of at least 5dbi. The antenna incorporates a flexible plastic portion protruding from the housing. The access point device may have one or more magnetic portions for releasable securing to a metallic surface and may be secured to a nacelle of a wind turbine. The access point device may be configured as a router, mesh gateway or repeater and may form a self-healing mesh network.

Simulation Results of 2.45 GHz Coaxial Antenna with a Ring Slot for Microwave Ablation of a Cancer

Abstract: Nowadays cancer is one of the leading causes of morbidity and mortality worldwide. Microwave ablation, as minimally invasive procedure, plays an increasingly important role in the treatment of cancer. In this thermal therapy, microwave energy delivery to a cancer tissue is enabled by electric fields radiated by interstitial antenna operating at microwave frequency. In this study, microwave ablation is numerically evaluated in the context of a liver cancer treatment using 2.45 GHz coaxial antenna with a ring slot. In order to design this antenna prototype and analyze its performance, simulations based on finite element method were done with the COMSOL Multiphysics software. In silico ablation experiments with the proposed antenna were performed using 10 W, 30 W and 50 W input microwave powers and different ablation times. Numerical results showed that the proposed ablation antenna has the ability to achieve a thermal lesion with a preferably spherical shape and clinically relevant volume with a maximum diameter of 3.5 cm using 30 W input microwave power during 10 minutes.

Coaxial antenna array microwave heating furnace

Abstract: According to the invention, one or two radiation arrays are employed for exciting a higher-mode Ten0 (n is an integer which is not less than two) behind or above a heating cavity of a coaxial antennaarray microwave heating furnace as much as possible, thereby forming standing waves in the heating cavity. The coaxial antenna array microwave heating furnace comprises the heating cavity and at leastone radiation array. The radiation array comprises at least two rows of radiators 1 along the Z axis. Any radiator is a coaxial antenna. Compared with multiple resonant modes that a microwave sourcein a conventional microwave oven excites the respective energy in the heating cavity at the same time through a waveguide and a coupling hole and are difficult to control, the working mode of the microwave heating furnace is determined in field distribution and can be controlled. In order to further improve the uniformity of heating, we use a rotating disk which can perform transverse translationor make precessional motion around the vertical axis of the heating cavity. According to the invention, the heating uniformity of the coaxial antenna array microwave heating furnace in a three-dimensional space is improved through controlling the microwave mode in a cavity of the coaxial antenna array microwave heating furnace. The coaxial antenna array microwave heating furnace can be used for the heating of various materials, or used for speeding up the chemical reaction.