Focusing the electromagnetic field radiated by an antenna at a point in the antenna near-field (NF) region is a wellknown technique to increase the electromagnetic power density in a size-limited spot region close to the antenna aperture. This article encompasses the basic working principles and the applications of the NF-focused (NFF) microwave antennas as well as the synthesis procedures suggested for the NF shaping around the focal point and the technologies currently used for their implementation.

/pdf/near-field-focused-microwave-antennas-near-field-shaping-and-46fyrtzm1f.pdf

Near-Field-Focused Microwave Antennas: Near-field shaping and implementation.

A 3-D focusing technique for noninvasive microwave hyperthermia treatment for breast cancer is presented and experimentally validated. The 3-D focusing is conducted to find the optimum excitations (phases and amplitudes) of a 3-D antenna array surrounding the breast using particle swarm optimization. The focusing approach aims at producing the required temperature (42 °C) at a tumor anywhere in the breast without causing hot spots in healthy tissue. Based on the modeling, a microwave system, which includes a 4.2-GHz source, power amplifier, two-stage power dividers, and phase shifters in addition to 24-element antenna array, was designed, built, and tested. The test was performed on the challenging scenario of a very dense breast phantom having 1-cm3 tumor embedded in glands. The experiments were conducted on a 3-D printed phantom that has realistic dielectric and thermal properties. The breast phantom was irradiated for one hour while the temperature distribution was recorded by thermal imager at different time intervals. The results confirmed the capability of the proposed 3-D focusing technique and experimental system in using 65-W microwave power to elevate the temperature at tumor to more than 42 °C while keeping healthy tissue safe at 36 °C without any hot spots.

3-D Focused Microwave Hyperthermia for Breast Cancer Treatment With Experimental Validation

This study studies optimal design of focused antenna arrays for microwave-induced hyperthermia. The phases and amplitudes of the driving signals of array elements are determined by optimising the power transmission efficiency of the system consisting of the transmitting antenna array, a receiving antenna located in the target area, and an equivalent phantom representative of human tissues. On the basis of the proposed technique, a 4 × 2 focused patch array is designed to operate on a fat-mimicking phantom with working frequency at 433 MHz. The measured patterns for specific absorption rate indicate that the energy is focused in the desired spot and are in close agreement with simulations, which validate the optimisation method in a medium with low permittivity and low loss. A 4 × 3 focused patch array operating on a human body phantom with same working frequency is then designed, in which an air space and two additional dielectric layers have been introduced between the planar array and the body-mimicking phantom for impedance matching. A good focal performance at desired spot is also achieved, and the simulated and measured specific absorption rate patterns agree very well. This demonstrates the validity of the proposed design method in a medium with high permittivity and high loss.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-map.2014.0696

Optimal design of focused arrays for microwave-induced hyperthermia

This paper provides a review spanning different technologies used to implement near-field focused antennas at the microwave frequency band up to a few tens of GHz: arrays of microstrip patches and printed dipoles, arrays of dielectric resonator antennas, reflectarrays, transmitarrays, Fresnel zone plate lenses, leaky-wave antennas, and waveguide arrays.

/pdf/technologies-for-near-field-focused-microwave-antennas-17bwujdrqr.pdf

Technologies for Near-Field Focused Microwave Antennas

This study presents a general and systematic method for three-dimensional pattern analysis and beamforming with distortionless co-polarisation for arbitrary conformal arrays. The method is based on the mathematical framework of geometric algebra and is able to consider element patterns which are both directional and polarised to produce a compact representation of the array pattern. As well as being simpler and more direct than derivations in the current literature, the method provides a visually intuitive means of dealing with the many frame conversions necessary in conformal array analysis. Geometric algebra provides us with an analysis tool, which is simpler and more practical than the traditional Euler rotation and matrix representations. Here a space-polarisation filter based on a conventional delay-and-sum structure is proposed for the pattern beamforming for conformal arrays. Filters assigned to each antenna are used to acquire the overall array pattern and the authors use the co-polarisation component to realise beamforming. In addition to the new derivation, the authors compare with traditional methods and present simulations on a cylindrical conformal array.

Beamforming with distortionless co-polarisation for conformal arrays based on geometric algebra

Microwave hyperthermia is rapidly evolving as a fourth modality in the fight against cancer, along with surgery, radiation and chemotherapy. This form of cancer treatment utilises a narrow microwave beam to heat the tumour volume to a temperature of ∼42°C; however, with minimal energy delivery to neighbouring healthy tissue, which is one of the main challenges in hyperthermia technology. Potentially, this application can be achieved by using a phased array of apertures or dipoles to generate and control the beam focus within the near-field treatment region. This paper describes another approach to near-field beam forming by using of a conformal waveguide array, operating in the K band (18–26 GHz). The array comprises a central movable element that acts as the focusing element, and surrounding fixed directing elements. The focusing element gives conformal property to the array and serves two purposes: firstly to obtain a sharp focus at a prescribed near-field location, and secondly the added flexibility to move the beam around the tumour. Several simulations and measurements have been performed on linear and planar configurations, which demonstrate the ability of the array to achieve beam widths as small as∼4 mm, with a maximum beam movement range of ∼15 mm.

Design, simulation and experimental study of near-field beam forming techniques using conformal waveguide arrays

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

R. Tulpule

Author Tools

Chat about Author

Papers

Design, simulation and experimental study of near-field beam forming techniques using conformal waveguide arrays