N101-020 TITLE: Multi-Channel Wideband Antenna Array Manifolds

TECHNOLOGY AREAS: Air Platform, Sensors, Electronics

ACQUISITION PROGRAM: PMA-290, Maritime Patrol and Reconnaissance Aircraft

OBJECTIVE: Develop innovative array manifold design for reconfigurable multi-channel antenna arrays for radar, communications and electronic warfare.

DESCRIPTION: Most phase scanned arrays have limited bandwidth when they scan off axis. The greater the scan angle, the more the bandwidth is limited. For wide bandwidth applications, such as a synthetic aperture radar and inverse synthetic aperture radar modes, a 500 to over 1000 MHz wide band may have to be covered with three or more frequency overlapped pulses. The pulses are then combined in the frequency domain through signal processing to achieve the required resolution. This effectively reduces the pulse repetition frequency by a factor of three or more and requires extra processing, which could be avoided with some time delay compensation.

In addition to scan performance, accurate monopulse processing used in many modern radars, is required. These are all based on multiple channel systems. In a typical generic antenna topology the aperture is segmented in azimuth or elevation, or both and then combined either digitally or with analog combiners to form Sum, Delta Azimuth and Delta Elevation channels. This technique yields between 10:1 and 20:1 precision improvement over the beam width. A more flexible channel configuration is needed for when other modes are required in addition to air-to-air. For example if Ground Moving Target Indicator (GMTI) and Maritime Moving Target Indicator (MMTI) modes are also required, a more optimal manifold would support eight subarrays feeding a switchable manifold feeding three receivers. Such a configuration could include the possibility of a guard channel. Normally, the signal splits and switches would degrade the system noise figure to unacceptable levels. However, a key advantage of an Active Electronically Scanned Array (AESA) system is that the Low Noise Amplifier (LNA) is at the element where it sets the noise figure. The losses after the LNA do not significantly contribute to the noise figure. Signals can be split and switches can be used. Wide band multi-channel manifold research is needed to exploit the full capabilities of modern AESA based sensors.

The design should be capable of supporting a minimum bandwidth of 500 MHz. The manifold design should include the ability to support multiple subarray configurations to maximize performance of air-to-air and GMTI/MMTI modes along with a guard channel. The design should be of sufficient detail to allow an independent assessment of the design.

PHASE I: Develop and prove feasibility of a detailed conceptual design for a wide-band multi-channel manifold suitable for a candidate X or C-band array.

PHASE II: Utilizing Phase I design, assemble, test and demonstrate a prototype manifold capable of working with the candidate array. Investigate and define the packaging and I/O requirements to ensure suitability for transition of the design.

PHASE III: Transition the technology to the operational fleet and commercial applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: High performance array manifolds are needed on a wide range of civilian and military sensor systems to support multiple surveillance requirements in a near simultaneous manner.

REFERENCES:
1. Alexopoulos, A., "Radar Systems Considerations for Phased Array Aperture Design Using Conformal Transformations on Riemannian Manifolds", IEEE Transactions on Antennas and Propagation, 55(8), pp 2239-2246, August 2007.

2. Golio, John Michael, "The RF and Microwave Handbook", Edition: 2, CRC Press, 2001.

3. Schreiner, M.; Leier, H.; Menzel, W.; Feldle, H.-P., "Architecture And Interconnect Technologies For A Novel Conformal Active Phased Array Radar Module", Microwave Symposium Digest, 2003, IEEE MTT-S International, Volume 1, Issue , 8-13 June 2003 Page(s): 567 - 570 vol. 1.

KEYWORDS: Radar; Electronic Warfare; Array; Array Manifold; Multi-Channel; Multi-Mode

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