Linearly and circularly polarized conformal strip-fed dielectric resonator antennas (DRAs) are studied in this article. In the latter case, a parasitic patch is used to excite a nearly degenerate mode. The hemispherical DRA, excited in its fundamental broadside TE111 mode, is used for the demonstration. In the analysis, the mode-matching method is used to obtain the Green's functions, whereas the method of moments is used to solve for the unknown strip currents. In order to solve the singularity problem of the Green's functions, a recurrence technique is used to evaluate the impedance integrals. This greatly increases the numerical efficiency. Measurements were carried out to verify the calculations, with good results.


Keywords:

circularly polarized antenna;
dielectric antennas;
mode-matching methods;
moment methods;
parasitic antennas;
resonance

Dielectric Resonator Antennas

In recent years, the dielectric resonator antenna (DRA) has emerged as a new and viable alternative to conventional low-gain elements such as dipoles, monopoles, and microstrip patches. This practical resource presents complete, up-to-date details on DRAs in a single volume. The book provides you with clear guidance on the mode of operation and radiation behavior of DRAs, the main methods of excitation, and the major advances in DRA technology. This hands-on reference equips you with simple equations and graphs that help you rapidly design DRAs of spherical, cylindrical, and rectangular shapes, without having to resort to complex analytical or numerical calculations. You find guidelines for designing feeds required to excite the DRAs, such as probes, apertures, and microstrip lines. In addition, the book offers you various techniques for enhancing the bandwidth performance of DRAs for wideband applications. You learn how to design low profile DRAs and DRAs with circular polarization. Several approaches for designing linear and planar DRAs arrays are also considered. Moreover, this comprehensive book provides advice on the fabrication of DRAs and measurement methods used to characterize their performance. Numerous design examples are included to give you a sense of the versatility that DRAs afford.

Dielectric resonator antenna handbook

Bi- and multistatic synthetic aperture radar (SAR) operates with distinct transmit and receive antennas that are mounted on separate platforms. Such a spatial separation has several operational advantages, which will increase the capability, reliability and flexibility of future SAR missions. Various spaceborne bi- and multistatic SAR configurations are introduced, and their potential for different applications such as frequent monitoring, wide-swath imaging, scene classification, single pass cross-track interferometry and resolution enhancement is compared. Furthermore, some major challenges such as phase and time synchronisation, bi- and multistatic SAR processing, satellite orbit selection and relative position sensing are addressed.

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Spaceborne bi- and multistatic SAR: potential and challenges

The present article is an introductory paper in this special issue on synthetic aperture radar (SAR). A short review is presented on the recent trend and development of SAR and related techniques with selected topics, including the fields of applications, specifications of airborne and spaceborne SARs, and information contents in and interpretations of amplitude data, interferometric SAR (InSAR) data, and polarimetric SAR (PolSAR) data. The review is by no means extensive, and as such only brief summaries of of each selected topics and key references are provided. For further details, the readers are recommended to read the literature given in the references theirin.

Recent Trend and Advance of Synthetic Aperture Radar with Selected Topics

A rectangular dielectric resonator antenna (DRA) was studied theoretically and experimentally. The rectangular DRA is excited by a strip, which is compatible with a coaxial probe. Both linearly polarized (LP) and circularly polarized (CP) fields of the antenna are considered. In previous studies of the LP rectangular DRA, only the fundamental TE/sub 111/ mode has received much attention. In this paper, it is found that the fundamental TE/sub 111/ mode, together with the higher-order TE/sub 113/ mode, can be used to design a wide-band LP DRA. The bandwidth of the dual-mode DRA can be over 40% for a conventional rectangular DRA with a simple feed. For the CP mode, a parasitic patch is attached on a side wall of the DRA to excite a degenerate mode. In both the LP and CP cases, the finite-difference time-domain (FDTD) method is used to analyze the problems. The results agree reasonably with measurements.

Strip-fed rectangular dielectric resonator antennas with/without a parasitic patch

A novel coupling scheme to a rectangular dielectric resonator antenna is proposed and investigated. In particular, coupling to the resonator is achieved through a narrow slot at the end of a coplanar waveguide (CPW). The objectives of this design are to maximize the coupling, match the dielectric resonator to the CPW feed line, achieve resonance at the desired frequency, obtain linear polarization with low cross polarization components, and minimize back radiation without using a back conductor. An approximate and quick design approach is given followed by more accurate design and analysis using commercial software. The antenna was fabricated and tested. Measurements match well with simulation results.

Coplanar-waveguide-fed slot-coupled rectangular dielectric resonator antenna

Based on the concept of effective dimensions, a modification to the conventional waveguide model (CWGM), usually used to predict the resonant frequency of rectangular DRA, is introduced. Compared with the experimental results, it is found that this newly introduced MWGM yields more accurate results for the resonant frequency than the CWGM. Accuracy of the results is also checked by comparison with numerically calculated values using a TLM-based commercial software. It is also found that the MWGM not only yields accurate values, but also results in considerable computation time savings. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 158–160, 1998.

Modified waveguide model (MWGM) for rectangular dielectric resonator antenna (DRA)

A novel coupling scheme to rectangular dielectric resonator antenna is proposed and investigated. In particular, coupling to the resonator is achieved through narrow slot at the end of a coplanar waveguide (CPW). The objectives of this design are to maximize the coupling, match the dielectric resonator to the CPW feed line, achieve resonance at the desired frequency, obtain linear polarization with low-cross polarization components, and minimize back radiation without using back conductor. An approximate and quick design approach is given followed by more accurate design and analysis using commercial software. The antenna was fabricated and tested. Measurements match well with simulation results. Index Terms—Coplanar waveguide (CPW), dielectric res- onators, measurement, radiation.

Coplanar-Waveguide-Fed Slot-Coupled Rectangular

In SAR applications two important frequency bands are the L-band, around 1.275 GHz, and the C-band at 5.3 GHz. The nominal bandwidth at both bands is desirable to be about 100 MHz. The authors report the design and construction of a dual band antenna for SAR in which the L band elements are perforated. The configuration is discussed and measurements of impedance and radiation patterns are given.

Dual-band dual-polarized microstrip antennas for SAR applications

The RADARSAT Constellation is an evolution of the RADARSAT program with the objective of assuring C-band data continuity in the next decade with improved operational use of Synthetic Aperture Radar (SAR) and improved system reliability. This paper describes mission's main objectives and user requirements, as well as its concept and current status.

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Guy Seguin

Papers

Coplanar-waveguide-fed slot-coupled rectangular dielectric resonator antenna

Modified waveguide model (MWGM) for rectangular dielectric resonator antenna (DRA)

Coplanar-Waveguide-Fed Slot-Coupled Rectangular

Dual-band dual-polarized microstrip antennas for SAR applications

RADARSAT constellation, project objectives and status