Frequency‐adjustable circularly polarized dielectric resonator antenna

Abstract

energy of each pair, respectively, is 1 ϭ66 mJ, 2 ϭ 71 mJ, and ϭ 1 ϩ 2 ϭ 137 mJ; when two sets of electrode-pairs are triggered synchronously, the output energy is 0 ϭ 180 mJ. The relative energy increase can be worked out as R ϭ 0 Ϫ ϭ 31.4%, and the corresponding the theoretical value is 37.3% with T ϭ 0.2 and A ϭ 0.10.The theoretical value is in agreement with the experimental results.Comparing the experimental results of the above two examples with the respective theoretical values, shows that the experimental value is always a little lower than the theoretical value. Possible reasons are the nonuniform gas discharge in practical operation and the fact that the intracavity photons cannot operate fully in the very short pulse time.Experiments also showed that the output energy of the second electrode-pair set (B) 2 is also slightly higher than the output energy of the first electrode-pair set (A) 1 , and the output energy of the third electrode-pair set (C) 3 is also slightly higher than the output energy of the second electrode-pair set (B) 2 . This may be because under the condition of delay trigger, when the second set of electrode-pair begins to operate after the former pulse ends, there are still some photons present. This leads to the gain threshold condition of the later electrode-pair set being slightly better than that of the former electrode-pair set, thereby increasing the output energy.ABSTRACT: Design of a microstrip-line-feed slot-coupled cylindrical dielectric resonator antenna (DRA) for circular polarization (CP) is investigated experimentally. The occurrence of the two orthogonal neardegenerate resonant modes is mainly excited by a perturbed annular slot that is, a C-shaped slot. The CP resonant frequency can be adjusted by using different slot sizes. Experimental results of the proposed C-slot coupled DRA are presented and discussed.ABSTRACT: A new coplanar coupled waveguide (CCPW) with cylindrical shielding is analyzed with the use of conformal mapping, which can provide accurate and fast calculations. Closed-form expressions for odd-and even-mode capacitances per unit length and characteristic impedances are derived. Numerical results are provided. The accuracy of the closed-form expressions has been confirmed by comparison with results available in the literature for CCPW with planar and rectangular shielded structure.

Circularly Polarized Dielectric Resonator Antennas: Design and Developments

“…12 [16]. When annular slot symmetry is disturbed it is capable of supporting multiple resonant frequencies with [25] broadside radiation pattern.…”

“…different geometrical DRA shapes [18], slot excitation technique [16], strip and patch excitation technique [14] and slot with strip excitation technique [39]. Table 1 Fig.…”

“…They can be divided on the basis of different feeding methods which are single feed [11][12][13][14][15][16][17][18], multiple feeds [13] and sequential rotation methods [12][13][14][15]. By exciting two quasi-degenerate orthogonal modes which are in phase quadrature, a single feeding technique for generating the circular polarization is obtained.…”

“…Slot coupling is the most popular excitation technique for the DRA design due to its direct integration with monolithic microwave integrated circuits (MMICS) [17]. In slot fed DRAs, by using different slot sizes wide frequency-band selections are achieved for a DR element [16]. To achieve wider impedance bandwidth annular slot is better than the rectangular slot excitation technique [17].…”

“…Later, a cylindrical ring dielectric resonator produced circular polarization by exciting the two orthogonal HE 11d modes in phase quadrature [8]. A special coupling slot has been used to excite the DRA for circular polarization such as a cylindrical DRA excited by, a cross slot of unequal length [12], a perturbed annular slot, a C-shaped slot [16], an asymmetrical U-slot [19], a hemispherical DRA excited by a shorted annular slot [21], a cross-slot-coupled hemi-ellipsoidal DRA [25], an elliptical dielectric ring resonator is excited by an aperture-coupled microstrip patch with reversed T-shaped slot [64], a rectangular stair shaped DRA excited by a narrow rectangular slot and rotated 45°with respect to the sides of the DRA [26], a cylindrical DRA fed by four sequentially rotated slots [35]. To excite the CP DRA, the use of a conformal strip has been also reported such as cylindrical DRA excited by two conformal strips of unequal lengths [13], a rectangular DRA fed by two vertical strips in phase quadrature for a dual-mode operation [32], a metallic strip has been printed diagonally on the top face of the square DRA and fed by a slot [15], a conducting strip loaded cylindrical DRA [24], a quadruple strip feed cylindrical DRA utilizing a pair of 90°hybrid couplers [30], a dielectric resonator-loaded circular microstrip patch antennas are also studied [61].…”