Search

A new decoupling scheme called dual-band coupled resonator decoupling network (CRDN) is presented. By properly designing the coupling coefficients between two pairs of coupled resonators, the network can effectively reduce the mutual couplings between two coupled dual-band antennas in two bands simultaneously. The new scheme is proved by a practical microstrip version of the device for two dual-band antennas working at 2.4 and 5.2 GHz frequency bands. A compact planar dual-band CRDN consisting of a pair of dual-band open-loop square ring resonators is proposed. The measured scattering parameters of two coupled antennas with and without the dual-band CRDN in free space (FS) and with hand phantom demonstrate that the isolation between the two antennas in both the low and high bands can be improved from 8 to 10 dB, respectively, to below 20 dB while maintaining a good matching performance. The total efficiency and envelop correlation coefficient for the decoupled antennas show a significant improvement as compared to the coupled antenna case. The proposed dual-band CRDN scheme is easy to be implemented in an integrated device, and is very attractive for practical multiple input and multiple output (MIMO) applications. [ABSTRACT FROM PUBLISHER]

The gain bandwidth constraint of sequential-rotation arrays (SRAs) has been an open issue since it was first pointed out in 1989. This paper reveals the reason, provides some useful conclusions and proposes an optimum design. Firstly, a first-order analytical formula is derived for the array factor (AF) of the 4-element sub-SRA. The formula embraces the polarization properties of the antenna elements. The AF is found to be dependent on the elements' polarization properties and frequency, which is not found in conventional regular arrays. Based on the theoretical results and full-wave simulations, these dependencies are analyzed in detail. Secondly, an optimum design is proposed to enhance the gain bandwidth: to constitute SRA with elliptically polarized elements (this type of SRA is denoted as EP-SRA) rather than the conventional circularly polarized elements (this type of SRA is denoted as CP-SRA). Detailed design guidance is presented for this new method. Finally, as an example, a CP-SRA and an EP-SRA are designed and tested for comparison. According to the example, by employing EP-SRA, the 1 dB AF bandwidth is improved by 80%, the measured 1 dB/3 dB gain bandwidth is enhanced by 114%/76%. In fact, the conventional CP-SRA and LP-SRA (SRA with linearly polarized elements) are two special cases of the proposed EP-SRA. [ABSTRACT FROM PUBLISHER]