This paper presents a single-layered broadband dual-band reflectarray with linear orthogonal polarizations in two adjacent bands. The reflectarray is designed to focus a broadside beam at 10.7 GHz -12.7 GHz band in vertical polarization and 12.7 GHz -14.7 GHz band in horizontal polarization respectively. Different to traditional square grids adopted in many reflectarray designs, this article proposes sub-wavelength rectangular grids in a single-layered structure for achieving broad bandwidth in both bands. Two pyramidal horn antennas with opposite positions are employed to feed the reflectarray for vertical and horizontal polarizations respectively. The elements consist of single-layered patches arranged in sub-wavelength rectangular grids. To realize the dual-band operation, one dimension of the patches is adjusted to direct the beam at the lower band in vertical polarization whereas the other orthogonal dimension is tuned to focus the beam at the upper band in horizontal polarization. The measured results show that the proposed dual-band reflectarray can realize a broad 1.5-dB gain bandwidth of 24% and 21% with aperture efficiency of 48% and 38% for the lower and upper band respectively, which demonstrates better behavior than various existing dual-band designs adopting traditional square grids.Index Terms-Single layer, rectangular patch, dual-band reflectarray, subwavelength.
0.045 k 0 3 0.16 k 0 , where k 0 is the wavelength in free space at the operating frequency, for example, 2.35 GHz. As shown in Figure 5, the measurements agree well with the circuit and full wave simulations. The insertion loss is less than or equal to 1 dB in the band of 2.32-2.4 GHz (minimum: 0.96 dB at 2.36 GHz), which includes the loss caused by the microstip-SICL transitions and the 2.4-2.4 connectors that are used for the measurement. The out-of-band spurious response is below 227 dB until 13.68 GHz (5.82f 0 ). It can be seen that the second harmonic is suppressed successfully as predicted.
CONCLUSIONThis article presents a BPF with extended rejection bandwidth based on SICL. A partial coupling scheme has been introduced for eliminating the harmonics, and the SICL technology ensures that the entire filter is arranged in a compact size. The experiments confirm that the proposed filter has merits of low loss, low crosstalk, easy integration, and a stopband up to 5.82f 0 , and it is a promising building block for high density integrated RF circuits.
This article presents a simple method to realize polarization diversity in broadband reflectarrays. The wideband characteristic of the reflectarray is achieved using rectangular patch elements arranged in a subwavelength grid on a single layer of substrate; while the polarization diversity of the reflectarray is obtained by simply rotating the feed horn antenna. As the two orthogonal x-and y-component of the rectangular patch element demonstrate relatively negligible interaction, the circular polarized (CP) reflectarrays with linearly polarized feed that have been proposed previously are found to be capable of supporting quadruple polarizations by means of rotating the feed. Based on the rectangular patch elements, an offset-fed 405 3 405 mm 2 reflectarray with 0.3k grid and centered at 10 GHz is designed and developed for right-hand circular polarization (RHCP). In an effort to realize the polarization diversity, the feed horn antenna is subsequently rotated relative to the array with angles of 0 , 90 , and 135 for vertical polarization, horizontal polarization, and left-hand circular polarization (LHCP), respectively. The viability and effectiveness of the proposed simple method for polarization diversity is experimentally verified. The measured results show that the 1-dB gain bandwidth for all four polarizations can reach as large as 18%. Furthermore, the 3-dB axial ratio bandwidths for CP operations are remarkably wide, above 36% and 40% for RHCP and LHCP, respectively. V C 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:305-310, 2015; View this article online at wileyonlinelibrary.com.
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