L. Duchesne

Feasibility of indoor spherical near field antenna measurement facility in VHF range

This paper details a study on the feasibility of an indoor antenna spherical near field measurement system in VHF range. Any constraints in terms of manufacturing or building are taken into account. Only electromagnetic and mechanical aspects required for antenna characterization are analyzed in order to appreciate such a measurement facility. After introduction on measurement needs in low VHF range, authors focus on ferrite performances analyses. Then a complete reflectivity analysis is done for each constituting elements of the facility. Finally is provided a global budget error to appreciate the feasibility of the antenna measurement system and prospects axes are discussed.

Field distribution of rectangular waveguides with anisotropic walls by using the modal theory

This article presents a new analytical approach to calculate very rapidely the field distribution in rectangular waveguides with anisotropic walls.

X-band compact choke horn antenna with circular polarization and isoflux pattern for nanosatellite applications

This paper presents a tradeoff between isoflux pattern quality and X-band antenna compactness for nanosatellite applications. Having an isoflux radiation and a circular polarization (CP) generally causes a large antenna size which is incompatible for these applications. A new design of an antenna is done with the following maximum antenna dimensions: a diameter of 90 mm and a height of 20 mm above the nanosatellite platform. The isoflux pattern is slightly degraded while a good CP and realized gain are kept. The structure is a compact choke horn. It presents an axial ratio lower than 3 dB and a RG close to 0 dB over a 400 MHz bandwidth (8.0–8.4 GHz). It has been realized and successfully measured.

High gain P-band antenna measurements in multi probe spherical near field range

A feed for a compact antenna test range operating in P-band in single polarization has been manufactured and tested in the SATIMO SG-64 multiprobe spherical near field test range in Paris. The feed consist of an array of 4 high gain log-periodic elements. This paper briefly describes the consideration on antenna design and manufacturing and report on the final testing including considerations on the associated measurement uncertainty.

On-Site Validation of a Microwave Breast Imaging System, before First Patient Study

This paper presents the Wavelia microwave breast imaging system that has been recently installed at the Galway University Hospital, Ireland, for a first-in-human pilot clinical test. Microwave breast imaging has been extensively investigated over the last two decades as an alternative imaging modality that could potentially bring complementary information to state-of-the-art modalities such as X-ray mammography. Following an overview of the main working principles of this technology, the Wavelia imaging system architecture is presented, as are the radar signal processing algorithms that are used in forming the microwave images in which small tumors could be detectable for disease diagnosis. The methodology and specific quality metrics that have been developed to properly evaluate and validate the performance of the imaging system using complex breast phantoms that are scanned at controlled measurement conditions are also presented in the paper. Indicative results from the application of this methodology to the on-site validation of the imaging system after its installation at the hospital for pilot clinical testing are thoroughly presented and discussed. Given that the imaging system is still at the prototype level of development, a rigorous quality assessment and system validation at nominal operating conditions is very important in order to ensure high-quality clinical data collection.

Modal Analysis of Rectangular Waveguides with 2D Metamaterials

A new method to rapidly design 2D metamaterials for rectangular waveguides by rebuilding their dispersion properties is proposed. The Modal Expansion Theory (MET) is revisited for theoretical surfaces with fixed surface impedances ZS . Then, it is pursued for real dispersive anisotropic surfaces, which have surface impedances that are dependent on the frequency and the incidence angle. An algorithm which calculates the correct incidence angle of the guided electromagnetic mode at each frequency is presented. By including this algorithm in the MET and by combining it with a code based on the Finite Element Method (FEM) to calculate the surfaces impedances, dispersion diagrams of waveguides with real 2D anisotropic walls are correctly rebuilt. This is validated by comparing the results for two different metamaterials, corrugationand T-structure, with those obtained using a commercial software.

Comparison of antenna measurement results in disturbed environment using a VHF spherical near field system

This paper presents parts of investigations done in a VHF spherical Near-Field system in order to propose appropriate measurement procedure. First is briefly presented the mono-probe near field system and measurement challenges due to low frequencies. Then is presented the Antenna Under Test (AUT), the antenna pattern comparison approach and the measurement configurations. Finally, several measurement results using two scans configurations are compared to reference simulation result in order to find the most appropriate way of measurement suited to the measurement facility for the large wavelength considered.