Designs of dualband antenna using the slot and dielectric resonator

Abstract

Today, dualband antennas are in great demand due to the rapid development of the modern wireless communications. The research reported in this dissertation is focused on new antenna designs for dualband applications which include linear polarization and circular polarization. A novel dualband hybrid antenna that consists of a zonal slot and a dielectric resonator antenna (DRA) is proposed in the first part of the dissertation. The DRA is placed on top of a slotted cavity to form a hybrid antenna. The cavity slot is fed by an embedded L-probe, whereas the DRA is fed by a rectangular coupling slot cut on top face of the cavity. The resonance frequencies of the lower and upper bands are primarily dependent on the zonal slot and the DRA which greatly facilitates the dualband antenna design. To demonstrate the idea, the proposed hybrid dualband antenna is designed for IEEE 802.11a/b wireless local area network (WLAN) applications. Based on the idea in the first part, a new compact circularly polarized (CP) dualband DRA-slot hybrid antenna without external ground plane is studied in the second part. The zonal slot is perturbed by two symmetrical cut-sections on the lower cavity to excite CP fields in the lower band. A third cut is added on the upper cavity to fine-tune the axial ratio (AR). Two cross coupling slots with unequal lengths are used to replace the rectangular coupling slot to feed the CP fields of the DRA. In this design, two frequency bands and field polarizations can be controlled separately. To verify the idea, the proposed antenna was designed at 2.4/5.2 GHz for IMS-band applications to demonstrate the idea. In the third part, a novel CP dual-slot antenna fed by the L-probe is proposed for dualband applications. The antenna consists of a zonal slot and an annular slot which are cut onto a square conducting cavity with a protective dielectric cover. The zonal slot and annular slot are perturbed symmetrically and asymmetrically to excite CP fields two bands. The resonance frequencies of lower and upper bands are controlled by the zonal and annular slots, respectively, making design dualband antenna very easy. To verify the hypothesis, the proposed antenna was designed at 2.4/5.8 GHz for two IMS bands. The proposed antennas were investigated using the commercial software Ansoft HFSS. The reflection coefficient, radiation pattern, AR, radiation efficiency and gain of antennas were studied and various measurements were carried out to verify the simulation. Parametric studies of the proposed configurations were carried out to characterize the antennas.

Date of Award	15 Jul 2010
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Kwok Wa LEUNG (Supervisor)