Dual-band Dual-polarized Array Research Articles

A Mutual-Coupling-Suppressed Dual-Band Dual-Polarized Base Station Antenna Using Multiple Folded-Dipole Antenna

An interleaved shared-aperture dual-band dual-polarized base station array antenna is proposed in this article. The lower-band (LB) element is realized by using a multiple folded-dipole antenna (MFDA) and four parasitic loops. To interpret the working principle of the MFDA, a double folded-dipole antenna (DFDA) is firstly analyzed by using the transmission line (TL) model. Then, by combining two bended DFDAs and introducing four parasitic loops, a low cross-band scattering LB element with a high out-of-band rejection level of 16 dB is obtained to cover 2.3–2.7 GHz. The higher-band (HB) element with a wide impedance bandwidth of 42.5% (3.0–4.6 GHz), a high roll-off rate (RoR) of 249.2 dB/GHz, and a high out-of-band rejection level of 17 dB is obtained by introducing a meander line loop (MLL), a rectangular loop (RL), and V-shaped strips (VSS) near the dipole arms. By combining the proposed low-scattering low-pass LB element and the high- RoR high-pass HB element, a novel interleaved shared-aperture dual-band dual-polarized array antenna with a small frequency ratio of 1.46 and a high cross-band isolation level of 25 dB is realized. Due to the low-scattering characteristic and filtering response of the LB element, the radiation patterns of the wideband HB sub-arrays are almost unaffected.

Decoupling and Low-Profile Design of Dual-Band Dual-Polarized Base Station Antennas Using Frequency-Selective Surface

A dual-band dual-polarized base station antenna array is developed for fifth generation (5G) applications. Low-profile characteristic, high isolations, and shared-aperture are realized by introducing a frequency-selective surface (FSS) between radiators operating in the 0.69–0.96 GHz (B1) and 3.5–4.9 GHz (B2) bands. The dual-polarized B1-band antenna has a low-profile height of $0.12~\lambda _{L}$ ( $\lambda _{L}$ is the wavelength at the center frequency of B1). As for the B2 band, a $2 \times 2$ dual-polarized array sharing the same aperture with the B1-band antenna is developed for the sub-6 GHz band. Severe mutual coupling between B1- and B2-band antennas is reduced by the FSS. High port isolation (> 25 dB) between B1- and B2-band antennas is achieved. A prototype consisting of one B1-band antenna and a $2 \times 2$ B2-band antenna array is fabricated. Measured results show that the proposed dual-band dual-polarized array achieves 32.7% and 33.3% bandwidth in the B1 and B2 bands, respectively. Measured results also demonstrate that the proposed array offers stable radiation patterns, high gains, and high cross-polarization discriminations (XPD > 20 dB) across the two frequency bands. These attractive features make this array an ideal candidate for future 5G massive MIMO base station antenna developments.

A Shared-Aperture Dual-Band Dual-Polarized Filtering-Antenna-Array With Improved Frequency Response

In this paper, a novel dual-band dual-polarized array antenna with low frequency ratio and integrated filtering characteristics is proposed. By employing a dual-mode stub-loaded resonator (SLR) to feed and tune with two patches, the two feed networks for each polarization can be combined, resulting in the reduction of the feed networks and the input ports. In addition, owing to the native dual resonant features of the SLR, the proposed antenna exhibits second-order filtering characteristics with improved bandwidth and out-of-band rejections. The antenna is synthesized and the design methodology is explained. The coupling coefficients between the SLR and the patches are investigated. To verify the design concept, a C-/X-band element and a $2 \times 2$ array are optimized and prototyped. Measured results agree well with the simulations, showing good performance in terms of bandwidth, filtering, harmonic suppression, and radiation at both bands. Such an integrated array design can be used to simplify the feed of a reflector antenna. To prove the concept, a paraboloid reflector fed by the proposed array is conceived and measured directivities of 24.6 dBi (24.7 dBi) and 28.6 dBi (29.2 dBi) for the X-polarization (Y-polarization) are obtained for the low- and high-band operations, respectively.

Combined feed network for a shared-aperture dual-band dual-polarized array

A new combined feed network is proposed for a shared-aperture dual-band dual-polarized array operating in the L/C band. The array comprises square, aperture-coupled patches in the C-band and a square perforated, aperture-coupled L-band patch. The feed networks of a single polarization for both the bands are combined into a single network on a single layer. Good return loss and radiation characteristics are obtained for L- and C-band frequencies.

Microstrip antennas for SAR applications

This paper discusses various methods of implementing a shared-aperture dual-frequency dual-polarized array antenna for spaced-based synthetic aperture radar (SAR) applications. After evaluating the use of several potential array architecture concepts and radiating elements, a design using interlaced C-band microstrip patches and X-band printed slot elements was chosen as the best choice for the present system requirements. Layout considerations for the two arrays and their associated feed networks are addressed in terms of a practical design. A dual-frequency (C- and X-band), dual-linear polarized SAR array antenna prototype was designed, fabricated, and tested. The principal goal of this effort was to demonstrate the viability of the dual-band dual-polarized array concept, and this has been accomplished. Test results are shown with good correlation between measured and predicted results, validating the design approach used. This work demonstrates that a dual-frequency dual-polarization SAR antenna within a single aperture is a feasible approach to meeting user requirements in future SAR spacecraft.