A key challenge in the design of wideband dipole phased arrays is the design of equally wideband baluns which are sufficiently compact to fit within the unit cell (typically in the linear dimension at low frequencies). In this paper, we exploit the reactance of a compact Marchand balun as an impedance matching network for each array element. The elimination of bulky external baluns results in a significant reduction of size, weight and cost, while the bandwidth is simultaneously improved by over 30%, compared to standard feeding techniques. In this manner, a tightly coupled dipole array with an integrated balun (TCDA-IB) is developed which achieves 7.35:1 bandwidth (0.68 - 5.0 GHz) while scanning to ±45° in all directions, subject to . In a dual-polarization configuration, the TCDA-IB has low cross polarization of over the majority of the band. Measured results are presented for a prototype 8 × 8 element TCDA-IB, showing good agreement with simulation.

A Wideband, Wide Scanning Tightly Coupled Dipole Array With Integrated Balun (TCDA-IB)

We present a wideband tightly coupled dipole array (TCDA) with integrated balun and a novel superstrate consisting of printed frequency selective surface (FSS) for wide angle scanning. Although previous TCDAs have had decent scanning performance up to ±60°, use of dielectric superstrates are usually required, resulting in additional cost and fabrication complexity. In this paper, we replace the bulky dielectric layer(s) with periodic printed elements and yet achieve wide-angle and wideband impedance matching. The proposed approach provides superior performance of 6.1:1 bandwidth (0.5–3.1 GHz) with VSWR $E$ plane, ±70° in $D$ plane and ±60° in $H$ plane. The FSS, radiating dipoles and feed lines are designed and fabricated on the same vertically oriented printed circuit board, resulting in a low-cost and lightweight structure as compared to other low profile arrays. Measured scanning patterns of a $12 \times 12$ prototype are presented, showing good agreement with simulations.

Ultrawideband Array With 70° Scanning Using FSS Superstrate

The theory, design, fabrication, and measurement of a new class of planar ultrawideband modular antenna (PUMA) arrays are presented. The proposed PUMA array class achieves twice the bandwidth (from 3:1 to 6:1) of the conventional shorted via-based PUMA without using an external matching network and while retaining convenient unbalanced feeding, manufacturing, and assembly characteristics. The chief enabling technical innovation hinges upon the reconfiguration of shorting vias into capacitively-loaded vias that simultaneously: 1) mitigate low-frequency bandwidth-limiting loop modes and 2) shift problematic common-mode resonances out-of-band. A simple theoretical model based on ridged waveguides is proposed that qualitatively and quantitatively explains this novel common-mode mitigation. An infinite array operating over 3.53–21.2 GHz (6:1) is designed to achieve active VSWR < {2, 2.5, 3.8} while scanning to {broadside, 45°, 60°}, respectively, without oversampling the aperture. D-plane cross-polarization is around {−15, −10} dB for {45°, 60°} scans with high efficiency, i.e., 0.5 dB co-polarized gain loss on average. A dual-polarized prototype 256-port (128 elements per polarization) array is fabricated and measured having good agreement with full-wave finite array simulations.

A New Class of Planar Ultrawideband Modular Antenna Arrays With Improved Bandwidth

It is traditionally known that wideband apertures lose bandwidth when placed over a ground plane. To overcome this issue, this paper introduces a new non-symmetric tightly coupled dipole element for wideband phased arrays. The proposed array antenna incorporates additional degrees of freedom to control capacitance and cancel the ground plane inductance. Specifically, each arm on the dipole is different than the other (or non-symmetric). The arms are identical near the center feed section but dissimilar towards the ends, forming a ball-and-cup. It is demonstrated that the non-symmetric qualities achieve wideband performance. Concurrently, a design example for planar installation with balun and matching network is presented to cover X-band. The balun avoids extraneous radiation, maintains the array's low-profile height and is printed on top of the ground plane connecting to the array aperture with 180° out of phase vertical twin-wire transmission lines. To demonstrate the concept, a 64-element array with integrated feed and matching network is designed, fabricated and verified experimentally. The array aperture is placed λ/7 (at 8 GHz) above the ground plane and shown to maintain a active VSWR less than 2 from 8-12.5 GHz while scanning up to 70° and 60° in E- and H-plane, respectively. The array's simulated diagonal plane cross-polarization is approximately 10 dB below the co-polarized component during 60° diagonal scan and follows the theoretical limit for an infinite current sheet.

Wideband Planar Array With Integrated Feed and Matching Network for Wide-Angle Scanning

Crossed dipole antennas have been widely developed for current and future wireless communication systems. They can generate isotropic, omnidirectional, dual-polarized (DP), and circularly polarized (CP) radiation. Moreover, by incorporating a variety of primary radiation elements, they are suitable for single-band, multiband, and wideband operations. This article presents a review of the designs, characteristics, and applications of crossed dipole antennas along with the recent developments of single-feed CP configurations. The considerations of profile miniaturization, radiation pattern control, bandwidth enhancement, and multiband operation are emphasized.

Crossed Dipole Antennas: A review.

In this paper we present the design, fabrication and demonstration of an X-band phased array capable of wide-angle scanning. A new non-symmetric element for wideband tightly coupled dipole arrays is integrated with a low-profile microstrip balun printed on the array ground plane. The feed connects to the array aperture with vertical twin-wire transmission lines that concurrently perform impedance matching. The proposed element arms are identical near the center feed portion but dissimilar towards the ends, forming a ball-and-cup. A 64 element array prototype is verified experimentally and compared to numerical simulation. The array aperture is placed λ/7 (at 8 GHz) above a ground plane and shown to maintain a VSWR < 2 from 8–12.5 GHz while scanning up to 75° and 60° in E and H-plane, respectively.

Broadband planar wide-scan array employing tightly coupled elements and integrated balun

This letter presents a miniature conformal array that provides continuous coverage and good axial ratio from 1100-1600 MHz. Concurrently, it maintains greater than 1.5 dBic RHCP gain and return loss less than -10 dB. The four element array is comprised of two-arm slot spirals with lightweight polymer substrate dielectric loading and a novel termination resistor topology. Multiple elements provide the capability to suppress interfering signals common in GNSS applications. The array, including feeding network, is 3.5" times 3.5" times 0.8" in size and fits into the FRPA-3 footprint and radome.

Miniature Continuous Coverage Antenna Array for GNSS Receivers

This letter presents a miniature L-band (770-1700 MHz) crossed bowtie antenna with integrated microstrip matching network and balun. Curved bowtie edges are employed for miniaturization and maintain nearly constant input impedance. The antenna provides dual linear polarization with greater than 5 dBi gain and exhibits a return loss greater than 10 dB when placed 1.5 in (λ/10 at 770 MHz) above a ground plane.

A Planar Dual Linear-Polarized Antenna With Integrated Balun

With space at a premium, there is strong interest to develop a single ultra wideband (UWB) phased array capable of concurrently supporting communications, electronic warfare and radar functions. Recent focus on conformal designs present new challenges on wideband apertures which typically transform into narrowband or multiband configurations when placed on a ground plane. Therefore, the design of low-cost phased array apertures that are concurrently broadband and low-profile ( high /2) has been a continuing challenge.

Justin A. Kasemodel

Papers

Wideband Planar Array With Integrated Feed and Matching Network for Wide-Angle Scanning

Broadband planar wide-scan array employing tightly coupled elements and integrated balun

Miniature Continuous Coverage Antenna Array for GNSS Receivers

A Planar Dual Linear-Polarized Antenna With Integrated Balun

Low-cost, planar and wideband phased array with integrated balun and matching network for wide-angle scanning