Fundamental issues in antenna design for microwave medical imaging applications

This paper surveys the development of microwave medical imaging and the fundamental challenges associated with microwave antennas design for medical imaging applications. Different microwave antennas used in medical imaging applications such as monopoles, bow-tie, vivaldi and pyramidal horn antennas are discussed. The challenges faced when the latter used in medical imaging environment are detailed. The paper provides the possible solutions for the challenges at hand and also provides insight into the modelling work which will help the microwave engineering community to understand the behaviour of the microwave antennas in coupling media

Design, fabrication and testing of pyramidal horn antenna

Horn antennas are widely used in areas of wireless communications, electromagnetic sensing, nondestructive testing and evaluation, radio frequency heating and biomedicine. They are also widely used as high gain elements in phased arrays and as feed elements for reflectors and lens antennas in satellite, microwave and millimeter wave systems. Moreover, they serve as a universal standard for calibration and gain measurements of other antennas.An optimum pyramidal horn with gain 20dB and center frequency 9.5GHz is designed. Using the design values two horn antennas are fabricated using aluminum sheets of different thickness namely 1mm and 2mm. The performance parameters like gain, directivity, impedance and s parameters are evaluated. The results are discussed

Design of an Ultra-Wideband Spiral Antenna for Ground-Penetrating Microwave Impulse Radar Applications

Radar systems that allow early detection of underground IEDs can save lives. The Microwave Impulse Radar (MIR) capable of IED detection requires antennas capable of transmitting sub-nanosecond pulses over ultra-wideband (UWB) frequency ranges. This thesis investigates the suitability of a novel MIR antenna for high-accuracy ground-penetrating radar (GPR) applications. Key GPR antenna considerations are pulse dispersion, size, and cost. UWB horn antennas provide excellent dispersion performance but limit system efficacy due to significant size and cost requirements. Micro-strip spiral antennas provide a low-cost alternative to UWB horn antennas, but common spiral designs demonstrate poor pulse dispersion performance. The article “Low-Dispersion Spiral Antennas” proposes using combination spirals, which combine the performance of multiple simple spiral antennas. This work investigates combination spiral suitability through 3D EM simulations and micro-strip fabrication. Testing results indicate that combination spirals possess improved pulse fidelity versus current spiral designs. Size and cost improvements are realized over horn antenna solutions. Updated simulation hardware and fabrication equipment could allow future combination spiral antennas to rival horn antenna performance

Probe modeling for millimeter-wave integrated-circuit horn antennas

Integrated-circuit probe-excited horn-antenna arrays etched in silicon are well developed. They are a very promising class of antenna arrays for milli-meter and submillimeter applications. Further development of this technology involves integrating mixers and amplifiers into the antenna arrays. In an effort to develop an antenna-mixer array based on the existing technology, various antenna probes inside the pyramidal horns have been examined on scaled model-horns at the microwave frequencies. In this paper, modeling results and design principles of these antenna probes have been presented, which include the resonant impedance, the operating frequency, and the bandwidth of the horn antennas. These measurement results provide a guideline in designing probes for millimeter/submillimeter-wave integrated-circuit horn-antenna-mixer arrays

3-D printed UWB microwave bodyscope for biomedical measurements

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this letter, a three-dimensional (3-D) printed compact ultrawideband (UWB) extended gap ridge horn (EGRH) antenna designed to be used for biological measurements of the human body is described. The operational frequency covers the microwave band of interest from 0.5 to 3.0 GHz (for an S 11 under -7 dB). The 3-D printed EGRH antenna is dielectrically matched to the permittivity of the human body, and because of its compactness, it can be visualized as a general-purpose microwave probe among the RF biomedical community. The probe has proven its capability as a pass-through propagation sensor for different parts of the human body and as a sensor detecting a 1 cm diameter object placed inside an artificial head phantom.Peer ReviewedPostprint (author's final draft

Large field homogeneous illumination in microwave-induced thermoacoustic tomography based on a quasi-conical spiral antenna

Conventional helical and horn antennas based on frequency selective surfaces have been used to provide microwave illumination in microwave-induced thermoacoustic tomography (TAT). However, the electromagnetic waves radiated from the conventional antennas are not circularly polarized and thus impair image quality. In addition, conventional antennas can provide uniform radiations only within a relatively small area and thus limit their clinical applications (e.g., breast imaging). To address these problems, we propose a quasi-conical log-spiral antenna for homogenous illumination over a large field. We theoretically and experimentally validated this approach. Tissue-mimicking phantoms were imaged. The antenna produced not only an electric field with a circular polarization but also a homogeneous illumination area with a 10 cm diameter. Accordingly, our method has advanced TAT by improving microwave illumination

Novel Planar Horn Antenna for 75/85 GHz Experimental Wireless Link

In the paper, we describe a novel H-plane horn antenna for an experi¬mental wireless link operating in frequency bands 71 to 76 GHz and 81 to 86 GHz. The horn antenna was designed considering a substrate integrated waveguide (SIW) technology, The waveguide WR12 was used as a feeder. In order to improve transition between a thin-substrate SIW horn antenna and the air, we combined two approaches; a printed transition and a dielectric load. That way, a better impedance matching and better radiation properties were reached. In comparison with other planar horn antennas, we obtained a more directional radiation pattern with more than 5 dB higher gain and sufficient side lobe suppression in the E-plane. The novel planar H-plane horn antenna was compared with a designed conventional metallic horn antenna