Nicholas K. Host

Ku-Band Traveling Wave Slot Array Scanned Via Positioning a Dielectric Plunger

This paper introduces a feeding concept aimed at eliminating the backend (phase shifters) of traditional phased arrays. A goal is to make phased arrays simpler and less costly for satellite communications. Accordingly, we employ a traveling wave array (TWA) using a single feedline whose propagation constant is controlled via a single, small, and mechanical movement of a dielectric plunger to enable scanning. The dielectric plunger is positioned within a parallel plate waveguide (PPW) transmission line (TL) that feeds the TWA. By adjusting the position of the dielectric plunger within the TL, the feedline achieves a propagation constant range of 1 ≤ keff/k0 ≤ 2.1, corresponding to scan angles of -32.6° ≤ θ ≤ 34.2° with an element spacing of d = 0.65λ0. That is, beam steering is achieved using a single feed and a simple linear mechanical movement (for any size array) without using phase shifters. A 20-element array was designed for stable realized gain across -25° ≤ θ ≤ 25° beam steering. Additionally, a proof of concept array was fabricated and measured. The simulated copolarized realized gain closely matches the fabricated TWA patterns.

Low cost beam-steering approach for a series-fed array

Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex and costly. This paper presents a concept which overcomes these detrimental attributes by eliminating all of the phased array backend (including phase shifters). Instead, a propagation constant reconfigurable transmission line in a series fed array arrangement is used to allow phase shifting with one small (≤100mil) linear mechanical motion. A novel slotted coplanar stripline design improves on previous transmission lines by demonstrating a greater control of propagation constant, thus allowing practical prototypes to be built. Also, beam steering pattern control is explored. We show that with correct choice of line impedance, pattern control is possible for all scan angles. A 20 element array scanning from -25° ≤ Θ ≤ 21° with mostly uniform gain at 13GHz is presented. Measured patterns show a reduced scan range of 12° ≤ Θ ≤ 25° due to a correctable manufacturing error as verified by simulation. Beam squint is measured to be ±2.5° for a 600MHz bandwidth and cross-pol is measured to be at least -15dB.

Causes of low scanning angle issues in phased array antennas

This paper analyzes the causes of issues encountered by phased arrays when attempting to scan to low angles. These issues include beam-width widening, gain reduction, increased power return to systems, and pattern degradation. Understanding the causes of these issues can lead to better phased array designs achieving beam steering to lower elevation angles.

Reconfigurable transmission line for a series-fed Ku-band phased array using a single feed

The paper presents a novel approach to realize a low-cost phased array using a simple feeding mechanism. Specifically, a single coplanar stripline (CPS) transmission line is used to feed the antenna array elements. By controlling the CPSs dielectric properties using a movable dielectric plunger, scanning is achieved. Due to its simplicity, single feed, and no phase shifters, this approach leads to a dramatic reduction in cost which does not scale for larger arrays.

Novel Phased-Array Scanning Employing a Single Feed Without Using Individual Phase Shifters [AMTA Corner]

Phased arrays afford many advantages over mechanically steered systems. However, they are also more complex, heavy, and, most of all, costly. The high cost mainly originates from the complex feeding structure. This paper proposes a novel feeding scheme to eliminate phase shifters and achieve scanning using a single control parameter. Beam scanning is achieved via a series-fed array, incorporating feeding transmission lines the wave velocity of which can be mechanically adjusted. Practical designs are shown that achieved scanning up to ±30° from boresight. Finally, a prototype was fabricated and measured, demonstrating the concept.

An X-band element-level digital receive array

This paper describes the design and fabrication of an experimental 32-element receive digital array. The array is intended as a tool for researching digital array technologies and techniques. The paper describes the array architecture, the components chosen and the design of the RF and digital subsystems. Measured results are presented that show the effectiveness of our array calibration and error correction approach and demonstrate the scaling and improvement of the array-level signal-to-noise ratio over that of a single array element.

Ku-band traveling wave slot array using simple scanning control

This paper introduces a feeding concept aimed at simplifying the backend (phase shifters) of traditional phased arrays. As an alternative to traditional phased arrays, we employ a traveling wave array (TWA) using a single feedline whose propagation constant is controlled via a single, small mechanical movement without a need for phase shifters to enable scanning. Specifically, a dielectric plunger is positioned within a parallel plate waveguide (PPW) transmission line (TL) that feeds the TWA. By adjusting the position of the dielectric plunger within the PPW feeding the TWA, beam steering is achieved. A 20 element array is designed at 13GHz shown to give stable realized gain across the angular range of -25° ≤ θ ≤ 25°. A proof of concept array is fabricated and measured to demonstrate and validate the concepts operation.