Continuous Transverse Stub Array Research Articles

An 8 x 4 Continuous Transverse Stub Array Fed by Coaxial Ports

An 8 x 4 Continuous Transverse Stub Array Fed by Coaxial Ports

A beam scanning continuous transverse stub array antenna for Ka‐band applications

AbstractA hybrid structure continuous transverse stub (CTS) array antenna for Ka‐band is demonstrated in this article. The array comprises 16 radiating slots, the H‐plane horn antenna based on the substrate integrated waveguide (SIW) and is fed by a corporate‐feed network in parallel plate waveguide (PPW) technology. The scanning angle of the main beam of the antenna reaches ±40° through switching the horn feed. Measurement shows that the CTS antenna has an relative bandwidth of 17.2% from 26.5 to 31.5 GHz for the standards of |S11| < −10 dB. At the center frequency of 29 GHz, the antenna gain of 28 dBi is obtained, the H‐plane sidelobe level (SLL) is −28.5 dB, and the radiation efficiency reaches 90%. The measurements are in very good agreement with full‐wave simulation results. The proposed design is suitable for Satcom Ka‐band terminals in moving platforms, for example, ships and planes.

Low-Profile Frequency-Scanned Antenna Based on Substrate Integrated Waveguide

A beam scanning flat antenna array with the frequency that covers about the whole X-/Ku-band is proposed in this communication. The radiation element is the continuous transverse stub (CTS) constituted by the substrate integrated waveguide (SIW). The feed structure is an SIW parabolic reflector fed by a linear source with a metallic post, which exhibits a good impedance matching characteristics within a broad bandwidth. The beam steering direction is tunable with the frequency increasing within the operation band. The design principles of the SIW-based CTS array and the feed structure are explained in detail. One 16-element array is simulated, designed, and fabricated. The measurement results show that the antenna has a scanning angle range from 52.2° to −16.8° with the 3-dB gain from 8.5 to 14.1 GHz. At the center frequency of 12 GHz, it achieves a maximum gain of 18.1 dBi with an array size of $11.7\lambda _{0}\times 1.28\lambda _{0}$ , while the first sidelobe level is −11.4 dB and the 3-dB beamwidth is 6.5°.

Beam-Scanning Continuous Transverse Stub Antenna Fed by a Ridged Waveguide Slot Array

A continuous transverse stub (CTS) array antenna is presented for beam-scanning applications. Rotatable ridged waveguide slot array (RWSA) is used as a line source to feed a CTS array for the first time. The proposed RWSA has easy design, compact structure, light weight, and easy sidelobe control. The CTS array and RWSA can be designed and optimized separately. A good beam-scanning capability of ±30° is achieved by rotating the RWSA at almost the same angles, thus obtaining a fine beam-scanning resolution. The measured aperture efficiency exceeds 60% in the entire beam-scanning range. Therefore, the proposed antenna can be a good alternative for radar systems and satellite communication terminals, which require low cost and high gain.

Continuous Transverse Stub Array for Ka-Band Applications

This paper presents a flat, high gain, wide scanning, broadband continuous transverse stub (CTS) array. The design procedure, the fabrication, and an exhaustive antenna characterization are described in details. The array comprises 16 radiating slots and is fed by a corporate-feed network in hollow parallel plate waveguide (PPW) technology. A pillbox-based linear source illuminates the corporate network and allows for beam steering. The antenna is designed by using an ad hoc mode matching code recently developed for CTS arrays, providing design guidelines. The assembly technique ensures the electrical contact among the various stages of the network without using any electromagnetic choke and any bonding process. The main beam of the antenna is mechanically steered over ±40° in elevation, by moving a compact horn within the focal plane of the pillbox feeding system. Excellent performances are achieved. The features of the beam are stable within the design 27.5-31 GHz band and beyond, in the entire Ka-band (26.5-40 GHz). An antenna gain of about 29 dBi is measured at broadside at 29.25 GHz and scan losses lower than 2 dB are reported at ±40°. The antenna efficiency exceeds 80% in the whole scan range. The very good agreement between measurements and simulations validates the design procedure. The proposed design is suitable for Satcom Ka-band terminals in moving platforms, e.g., trains and planes, and also for mobile ground stations, as a multibeam sectorial antenna.

Active Impedance of Infinite Parallel-Fed Continuous Transverse Stub Arrays

This paper introduces a rigorous and effective modeling framework for the continuous transverse stub (CTS) array, based on a spectral Green’s function approach. A multimodal expansion of the equivalent currents over the slots is used to derive an accurate expression for the active impedance of an infinite array. This formula is validated through comparisons with full-wave simulations when the array scans are in principal planes. The mathematical formulation highlights the broadband properties of CTS arrays and accurately predicts the impact of the geometrical parameters on the active impedance, as a function of frequency and scan angle. The discussion of the results provides physical insights to outline effective design strategies.

A Locally Conformal Algorithm for Handling Curved Metallic Surfaces and Its Application

This paper describes a modified locally conformal algorithm for finite-difference time-domain (FDTD) method. Fields in the entire computational domain are computed by a regular FDTD algorithm except those near curved metallic surfaces, where special techniques proposed in this paper are applied. The computation efficiency of a regular FDTD method is maintained while a high space-resolution is obtained by this new algorithm. To validate the reliability of the algorithm, coaxial continuous transverse stub arrays at millimeter wave Ka-band and microwave X-band are tested, and the simulated results show good agreement with the experimental results from an HP-8510B Network Analyzer and the simulation results from software package HFSS.