Allen Wang

Multiband phased-array antenna with interleaved tapered-elements and waveguide radiators

Multiband, multibeam, phased array antennas are required for todays multi-function radar and communication applications. These types of antennas play a major role in the shipboard and airborne environment, where space is limited. A single antenna is now asked to perform multiple functions, including long-range surveillance, navigation, weapons control, tracking and recognition, and electronic warfare support measures. A phased array antenna capable of covering several different frequency bands in a common aperture is highly desirable, and is currently being pursued for many of these applications. A number of multiband radar antenna configurations have been proposed in the past. An ultra-wideband phased array antenna design using interleaved waveguide elements and wideband tapered elements is presented. This phased array antenna can operate over at least three frequency bands. Numerical results of the aperture match for both types of radiators, including mutual interaction, are presented.

Dual-band, dual-polarization, interleaved cross-dipole and cavity-backed disc elements phased array antenna

In ship, submarine, or airborne satellite communication or multi-function radar operations, dual-band phased array antennas with dual-linear or circular polarizations are needed. We present a dual-band/dual-polarization phased array design using a interleaved cross-dipole radiator and a cavity-backed disk radiator in the same lattice structure. The low band radiator is a disk radiator sitting on top of a dielectric puck in a cavity and the high band radiator is the cross dipole element printed on a low-K dielectric layer above the disk-cavity plane. Dual-linear or circular polarizations can be achieved using these two elements to cover two separate bands with about a 2:1 ratio. This is a relatively low profile, compact and rigid array. Good impedance match for both bands can be obtained over a wide scan volume.

Planar, low-profile, wideband, wide-scan phased array antenna using stacked-disc radiator

Many of todays satellite communication and radar systems demand phased array antennas that are wideband and capable of dual linear or circular polarization. These types of antennas are necessary in order to achieve the desired multifunction operation and polarization diversity. A phased array antenna that satisfies these requirements have been developed. The antenna can provide an octave-bandwidth performance with excellent scan and polarization behavior. More importantly, it is very compact and low-profile in nature. The design of this planar array antenna is described. Its performance has been validated using a waveguide simulator and test array measurements. Some of these results are presented.

Analysis of wideband tapered element phased array antennas

A phased array of wideband tapered elements, such as the tapered slot and bunny-ear element, offer wide-band wide-scan capability for radar, EW, and communication applications. The analysis of infinite arrays of linear tapered slot antenna has been published by Cooley, Schaubert, Buris, and Urbanik (see IEEE Trans. Antennas Propagat., vol.AP-39, no.11, p.1615-1624, 1991). An experimental study of a wide-band bunny-ear element has been reported by Lee and Livingston (see IEEE AP-S International Symposium, Ann Harbor, MI, p.1604-1607, 1993). Although many interesting features have been observed for the bunny-ear element, there has not been a theoretical analysis on this element. The paper presents an analysis method based on the Greens functions for horizontal and vertical elemental dipoles over a ground plane in a periodic unit cell. The solution is formulated for the general two-dimensional tapered element in an infinite phased array environment using the Greens functions derived by Lee and Chu (1991). A computer program has been developed, and its results have been validated with the examples given by Cooley et al. The modeling results of the phased array of bunny-ear elements as described are also presented.<<ETX>>

Low-profile, integrated radiator tiles for wideband, circular-polarized phased array applications

A versatile planar, low-profile radiating element for phased array applications has been developed that can provide excellent scan and axial ratio performance over a very wide frequency bandwidth. The design is based on a stacked-disc configuration where the lower disc is fed by a pair of probes per linear polarisation. The stacked-disc radiator has since been integrated with its feed circuits in a very compact and versatile package. This package, referred to as an integrated radiator tile, is the building block for a very low-profile phased array aperture that can provide dual circular polarization. The radiator tiles form factor lends itself well to many conformal applications and tile array architectures in general. This paper presents an integrated radiator tile design that was developed for an active array antenna for submarine satellite communication. It describes the packaging scheme and shows the measured performance of the various components. A small test array was built using the radiator tiles to demonstrate its element performance. Its results are also discussed.

Low-profile, broadband, wide-scan, circular-polarized phased array radiator

A wideband low-profile, circular-polarized CNBLCP) phased array radiator has been developed for broadband phased array applications. The radiator is capable of providing common-phase-center circular- or dual-linear polarization, and wide scan volume over an octave bandwidth. These are all desirable features in todays phased array antennas for multifunction radar and satcom applications. The design of a new WBLCP element is presented along with its predicted frequency and scan performance. These calculated results have been validated using waveguide simulator measurements. A comparison of the predicted and measured results is also presented.

Analysis and design of a multi-band phased array using multi-feed dipole elements

Multifrequency-band phased array antennas are needed for airborne, shipboard, and ground based radar, communication, and EW applications. Such arrays can provide simultaneous, independently-scanned beams for multi-function operations. We have developed a multi-band phased array aperture which utilizes co-planar dipoles with multiple-feed ports to achieve a different effective dipole length for each operating frequency band. The basic geometry is shown. The radiating elements are connected to multiple excitation ports, where band-pass filters an used to achieve open- or short-circuit behavior at the desired operating frequency. Several frequency-selective ground screen layers may be placed behind the radiating layer to improve the match. The principle of operation is shown, using a dual-band cast as an example. In this simple dual-band case, both frequency bands of operation share a common solid ground plane. The analysis of this infinite array of multi-feed dipoles over a ground plane is given. An aperture design for tri-band operation is presented, together with the verification by waveguide simulator experiments. A parametric study of various ground screen effects is also summarized.