H.K. Ng

Theory and experiment of circularly polarized dielectric resonator antenna with a parasitic patch

The use of a single parasitic patch for circular polarization (CP) excitation of the dielectric resonator antenna (DRA) is investigated. For demonstration, the technique is applied to the conformal-strip fed hemispherical DRA, excited at the fundamental TE/sub 111/ mode. Using the Greens function approach, the integral equations for the conformal-strip and parasitic-patch currents are formulated by matching the appropriate boundary conditions. The equations are then solved using the method of moments (MoM). In using the MoM, both the rigorous and simplified current expansions are used for the parasitic patch, and their results are compared with each other. In each case, the impedance integrals are evaluated by virtue of newly obtained recurrence formulas and direct analytical integration. Hence, the results can be calculated very efficiently without the need for any numerical integration, which greatly facilitates the numerical implementation. The input impedance, axial ratio, and radiation patterns of the CP DRA are calculated, and the results are in good agreement with measurements.

The slot-coupled hemispherical dielectric resonator antenna with a parasitic patch: applications to the circularly polarized antenna and wide-band antenna

The aperture-coupled hemispherical dielectric resonator antenna (DRA) with a parasitic patch is studied rigorously. Using the Greens function approach, integral equations for the unknown patch and slot currents are formulated and solved using the method of moments. The theory is utilized to design a circularly polarized (CP) DRA and a wide-band linearly polarized (LP) DRA. In the former, the CP frequency and axial ratio (AR) can easily be controlled by the patch location and patch size, respectively, with the impedance matched by varying the slot length and microstrip stub length. It is important that the AR will not be affected when the input impedance is tuned, and the CP design is therefore greatly facilitated. For the wide-band LP antenna, a maximum bandwidth of 22% can be obtained, which is much wider than the previous bandwidth of 7.5% with no parasitic patches. Finally, the frequency-tuning characteristics of the proposed antenna are discussed. Since the parasitic patch can be applied to any DRAs, the method will find applications in practical DRA designs.

Frequency tuning of the linearly and circularly polarized dielectric resonator antennas using multiple parasitic strips

A rigorous analysis of the conformal-strip-excited hemispherical dielectric resonator antenna (DRA) with multiple parasitic strips is presented in this paper. The problem is formulated using the Greens function approach, with the strip currents solved by using the method of moments. It is found that the strips can be used to tune the operating frequency of both the linearly polarized (LP) and circularly polarized (CP) DRAs. In designing the LP DRA, the parasitic strips are placed symmetrically in pairs to minimize cross-polarized radiation fields. For the CP DRA, however, the parasitic strips are asymmetric, with their parameters determined by using the Genetic Algorithm. Measurements were carried out to verify the calculations, and reasonable agreement between theory and experiment is obtained.

Frequency tuning of the dielectric resonator antenna using a loading cap

A rigorous analysis of the slot-coupled hemispherical dielectric resonator top-loaded by a conducting cap is presented. The resonant frequency of the antenna can be tuned by changing the size of the loading cap. Measurements were carried out to verify the calculations, and reasonable agreement between theory and experiment is obtained.

Circular-polarized hemispherical dielectric resonator antenna excited by dual conformal-strip

The circularly polarized (CP) hemispherical dielectric resonator antenna (DRA) is excited by two conformal strips with 90/spl deg/ phase difference. More than 20% of the 3-dB axial ratio bandwidth is obtained. Good agreement between theory and experiment is observed.

Conformal-strip-excited dielectric resonator antenna with a parasitic strip

A conformed-strip-excited hemispherical dielectric resonator antenna (DRA) with a parasitic strip is investigated theoretically and experimentally. The moment method is used to solve the unknown strip currents, from which the input impedance of the configuration is found. The effect of the parasitic strip displacement on the DRA is studied. A good agreement between theory and experiment is obtained.

Frequency tuning of the dielectric resonator antenna using a loading disk

A rigorous analysis is done for the excitation of a hemispherical dielectric resonator antenna (DRA) loaded by a circular disk. The disk is placed on the top of the DRA for tuning the operating frequency. The method of moments (MoM) is used to solve the unknown currents, from which the input impedance and radiation field pattern of the configuration are found. Reasonable agreement between theory and experiment is obtained.

Excitation of CP aperture-coupled dielectric resonator antenna with a parasitic patch

Excitation of the circularly polarized (CP) aperture-coupled hemispherical dielectric resonator antenna (DRA) using a parasitic patch is studied. The analysis consists of two parts, namely the DRA with a parasitic patch and the microstrip feed line. In this paper, theoretical results on the return loss and radiation field pattern are presented.

Jumping genes paradigm for designing dielectric resonator antenna with multiple parasitic strips

The conformal-strip fed hemispherical dielectric resonator antenna (DRA) with multiple parasitic strips has been designed by jumping genes genetic algorithm. The corresponding Pareto-optimal fronts are obtained, showing the relation between impedance bandwidth and radiation pattern. The number of parasitic strips on linearly polarized (LP) and circularly polarized (CP) DRAs is optimized with the hierarchical genetic algorithm. The results showing the designed frequency, impedance bandwidth and radiation pattern are presented

Frequency design of the circularly polarized dielectric resonator antenna

The use of a parasitic annular slot for the circularly polarized (CP) dielectric resonator antenna (DRA) is studied theoretically and experimentally. The result involves neither a singularity nor any numerical integration and, therefore, is computationally very efficient. The voltage standing wave ratio, axial ratio, and radiation patterns of the antenna are presented. The effect of the parasitic slot is investigated.