Frequency Band Rejection Technique Based on the Operating Modes for a Wideband H-Shaped DRA

In this paper, a new approach to create frequency band rejection is applied to a wideband H-shaped dielectric resonator antenna (DRA). In order to create a notch characteristic in the operating band of the TEy1δ1 and TEy2δ1 modes, and guided by their theoretical and simulated electric field distributions, a narrow conductive strip is incorporated around the mid-section of the H-shaped DRA. The orientation of the notching strip is determined based on the electric field distribution of the selected modes for the frequency rejection. Furthermore, the selected feeding method improves the radiation patterns for this DRA shape compared to its previous designs. The new design offers an operating frequency range that extends from 4.15 to 9.8 GHz, allowing 81% of fractional bandwidth. The first notch is created at 6.5 GHz, while the second one is at 8 GHz. Average radiation efficiency of 95% across the frequency of interest is achieved with overall dimensions of 40x30x11.4 mm3. The proposed design is simulated using Ansys HFSS and validated by measurement.

Frequency reconfigurable antenna for cognitive radios with sequential UWB mode of perception and multiband mode of operation

In this work, an UWB/narrow band reconfigurable elliptical-shaped monopole antenna for cognitive radio applications with sequential perception and operation modes is presented. The proposed approach consists in integrating a reconfigurable filter, in an UWB antenna ground plan, by the mean of four horizontal slots and integrated switches that allow inserting/removing/varying zeros and poles in the frequency response. By acting on the slot lengths in order to alter their resonance frequencies, the different switch configurations allow the antenna to switch between an UWB mode that could be used for the perception (sensing) and different narrowband modes, mono-band and dual-band, that could be used for the operation at 2.4 or/and 3.5 GHz. To validate the concept, an experimental prototype has been fabricated and a good agreement between the simulated and the measured S-parameters has been obtained. While the presented work uses the presence/absence of a perfect conductive strip (PEC) to model real switch operation, it is believed that the obtained results conjugated with previous work using real switches on a very similar structure allows validating approach.