A single square patch antenna for pattern diversity is investigated. The proposed antenna consists of a double-feed square patch antenna with a rat-race network. By switching the feeding ports, the different radiation patterns for two modes (TM 10 mode and the capacitive-loaded monopole radiating mode) operating over an overlapped frequency band from 1.88 to 2.34 GHz are achieved. TM 10 mode reveals good broadside radiation patterns and the capacitive-loaded monopole radiating mode shows conical radiation patterns. The antenna is fabricated and tested. The measured gains across the common frequency band are 8.9-9.9 dBi and 2.8-3.8 dBi for TM 10 mode and the capacitive-loaded monopole radiating mode, respectively. Besides, the measured bandwidths of -10 dB reflection coefficient are 750 MHz (1.59-2.34 GHz, 38.2%) for TM 10 mode and 880 MHz (1.88-2.76 GHz, 37.9%) for the capacitive-loaded monopole radiating mode. High isolation (<-20dB) between the two feeding ports for the common impedance matching band is achieved. These results make the single dual-port patch antenna an attractive solution for 3G/4G pattern diversity applications such as in gym scenarios.
Abstract-A single-layer wideband printed antenna for dual-polarized applications is proposed in this paper. Two orthogonal linear polarizations are achieved by adopting a hybrid feeding technique. The horizontal polarization is excited by an aperture-coupled microstrip feed line while the coplanar waveguide (CPW) feed line is responsible for the vertical polarization. Measurements demonstrate a fairly wide common impedance bandwidth of 56.3% (1.61-2.87 GHz) with SWR ≤ 2 could be achieved. By loading a rectangular patch in the narrow rectangular slot, the isolation between two ports can be improved to better than 40 dB over the entire bandwidth. Moreover, the average gains of the proposed antenna are about 5.8 dBi and 5 dBi for port 1 and port 2, respectively.
A synthesis method for orthogonal beam-forming networks (BFNs) with arbitrary N inputs and N outputs is presented. Compared to those formerly developed, the new method allows the design of a BFN in order to not only generate arbitrary N orthogonal beams and N inputs but also to make the 180 • hybrids less. This skill is obtained by means of a new approach to decompose the matrices Q 1 and Q 2 which are mentioned by Sodin. The solution of such a design problem can be carried out by applying QR decomposition based on Givens transformations. Such a design method also takes into account the computer programming realization. Numerical results are obtained through the commercial simulator to prove the correctness of the method. The ease, accuracy, and efficiency of this synthesis method for the design of BFN make it very useful in modern applications of multi-beam antenna arrays. INDEX TERMS Orthogonal beam-forming network, butler matrix, arbitrary N beams, QR decomposition, Givens transformations.
A compact Rotman lens is presented in this paper. The compact Rotman lens consists of a lens body and truncated ports with the energy distribution slots. By truncating the long triangular transitions of the traditional Rotman lens, the lengths of lens ports are reduced effectively. However, the impedance discontinuity problem is caused by truncating the triangular transition. To solve this problem, the energy distribution slots are designed between the feed lines and the truncated lens body apertures. The energy distribution slot is evolved from the 1-2 power divider, which creates a transition process for the wave energy propagating from the feed lines and realizes good impedance match between the lens body and the feed lines. To validate the proposed design, a 4×7 Rotman lens has been designed and prototyped at 10 GHz. The Rotman lens exhibits a scanning range of ±33 • , 27% bandwidth for VSWR < 2, and the isolation between beam ports better than 17.2 dB within the operation bandwidth. Basing on the advantages of compact size, low cost, easy processing, and wide bandwidth, the proposed compact Rotman lens may have wide applications in the multi-beam antenna systems.
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