Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Wide-Angle Scanning Phased Array Antenna

Abstract: A cross-shaped wide angle scanning array antenna is studied and presented. High impedance periodic structure (HIPS) is applied to ameliorate radiation pattern of the antenna element in an array. The HIPS could improve the beam-width of an active antenna element in the array. Then the wide-angle scanning performance of the phased array is extended. The gain of the array antenna is improved when the main beam scans at ± 60° both in the H-plane and E-plane. By the comparison to the metal ground plane, the gain of the array antenna with HIPS is 4dB higher in H-plane when the main beams are at ± 60°. And the gain of the array antenna with HIPS is 2.6dB higher in E-plane when the main beams are at - 60°. The main beams are more symmetrical when they are at ± 60° in E-plane. The cross-shaped wide scanning array antenna with periodic structure is fabricated and measured. The main beam of the array antenna scans up to ± 60° with high gain is achieved in the H-plane and E-plane respectively. The measured results of the array are in good agreement with the simulated results.

Performance Analysis of Adaptive Generalized Spatial Modulation

Abstract: Generalized Spatial Modulation (GSM) plays a vital role in MIMO wireless system transmission technology that advances the concept of spatial modulation (SM) and also improves SM’s spectral efficiency. In this paper, we proposed Adaptive Generalized Spatial Modulation (AGSM) using Huffman Coding. Transmitter can decide active antenna combination probability mode based on feedback information which is obtained from receiver using Huffman mapping. The optimal active antenna combination probability is derived when Gaussian distributed input signal is applied by optimizing channel capacity. For optimization, lower and upper bound expressions for channel capacity for Adaptive Generalized Spatial Modulation (AGSM) Model is derived. In each SNR region, finding optimum active antenna combination probability mode through applying input as discrete QAM signal by minimizing symbol error rate performance. Numerical results show that our extended adaptive generalized transmission scheme provides better performance over Generalized Spatial Modulation (GSM).

Closed-Loop Sign Algorithms for Low-Complexity Digital Predistortion

Abstract: In this paper, we study digital predistortion (DPD) based linearization with specific focus on millimeter wave (mmW) active antenna arrays. Due to the very large channel bandwidths and beam-dependence of nonlinear distortion in such systems, we propose a closed-loop DPD learning architecture, look-up table (LUT) based memory DPD models, and low-complexity sign-based estimation algorithms, such that even continuous DPD learning could be technically feasible. To this end, three different learning algorithms - sign, signed regressor, and sign-sign - are formulated for the LUT-based DPD models, such that the potential rank deficiencies, experienced in earlier methods, are avoided. Then, extensive RF measurements utilizing a state-of-the-art mmW active antenna array system at 28 GHz are carried out and reported to validate the methods. Additionally, the processing and learning complexities of the considered methods are analyzed, which together with the measured linearization performance figures allow to assess the complexity-performance tradeoffs. Overall, the results show that efficient mmW array linearization can be obtained through the proposed methods.

A gallery mode oscillator for the low cost millimeter-wave active antenna array

Abstract: Dielectric Image Guide (DIG) is a convenient planar structure for low cost millimeter wave (MMW) circuits and antenna arrays. Exciting the DIG is important in some applications such as active antenna array and beam forming. The Dielectric Resonator (DR) is a conventional approach for coupling the excited mode to the DIG. Furthermore, we should find a proper way for making an oscillation in structure consisting of DIG and DR. So, the oscillator concept should be considered properly. Among semiconductor sources, Gunn oscillators have shown to be promising as low cost, simple and high power alternative in mm-wave and Terahertz range. It is also compatible configuration for this kind of antenna array. Conventionally, the oscillation frequency is stabilized by a cavity waveguide resonator [1]. At (sub) mm-wave wavelength, however, the waveguide cavity becomes impractically small in size and extremely sensitive to fabrication tolerances. To overcome this shortcoming, in this paper, we propose to stabilize the oscillation frequency through direct interaction of the Gunn diode with a whispering gallery mode (WGM) dielectric resonator (DR). The dimensions of a WGM resonator can be much larger than the operating wavelength [3], and therefore less sensitive to fabrication tolerances. In order to transmit the generated mm-wave signal to an external load, the structure is coupled to the DR. The proposed configuration is structurally capable to be integrated with three dimensional waveguide structures such as DIG or planar guiding like CPW or microstrip line.

Linear Polarized Matched-Input Active Integrated Transmit Antenna

Abstract: This paper shows the development of an active integrated transmit antenna which has linear polarization and a matched input. The active antenna comprises a rectangular microstrip patch that is fed by two FETs directly connected to its non-radiating edge. The FETs are driven equally but with a 180 degree phase difference by a modified branch-line coupler. Simulations of a 2.45 GHz active integrated antenna demonstrate the feasibility.