N102-159 TITLE: Consolidated Apertures with Co-site Interference Reduction in the Frequency Range 2 to 30 MHz

TECHNOLOGY AREAS: Ground/Sea Vehicles, Sensors

ACQUISITION PROGRAM: PMS 502, CGX Program, ACAT 1

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted." The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: Develop an innovative approach to enable the consolidation of multiple transmit and receive signals in the 2 to 30 MHz frequency range onto two transmit and one receive antennas.

DESCRIPTION: The topside of Navy ships is crowded and the space available for new antennas, systems and capabilities is limited by the number of existing topside systems. Co-site effects from new high-power phased array radars only compound this problem due to the required amount of space, weight, and power. Using dedicated antennas for each system also increases the likelihood of co-site interference between RF systems. Ultimately the lack of available topside real estate unacceptably constrains the performance of new systems. Additionally, there is a growing need for increased communications capabilities on Navy combatants. For new ships, and upgrades to existing ships, these increased communications capabilities combined with more stringent performance requirements drive a need for technology approaches that will increase throughput while reducing the number of antennas. One major technical challenge for topside systems is the requirement to operate in the presence of multiple, high-power, RF transmitters. This challenge is further complicated by the need to consolidate multiple signals onto fewer antennas to meet the communications requirements in the space available.

This topic seeks to meet these challenges by exploring the development of innovative new approaches for antenna consolidation and integrated co-site interference mitigation techniques. This need is especially acute in the 2 to 30 MHz (HF) range. The wavelengths in this frequency range are comparable to the dimensions of the ship; thus, spatial isolation between transmit and receive antennas is limited. Legacy systems that combine multiple signals onto a few antennas typically have significant insertion loss. For example, legacy systems when combining up to 16 signals have insertion losses no less than 12 dB per signal. Additionally, these legacy systems typically do not use Automatic Link Establishment (ALE) to select the optimum frequency for transmission [Reference 1]. The figures of merit for any proposed technology should include: ability to receive a signal while transmitting many high-power signals, the ability to change frequency rapidly to accommodate environmental change common to HF communications, and the reduction of insertion losses. Any technology solutions that can meet these goals should be considered. Examples of technology that have proven successful in the 30 to 400 MHz frequency range include comb filtration with linear combining and active feedback transmit signal cancellation [References 2, 3, and 4].

Representative and relational data will be provided, as needed, for this project during Phase II. All information provided and generated as a result of this effort will be unclassified.

PHASE I: Demonstrate the feasibility of an approach that will enable the consolidation of 2-30 MHz antennas with integrated co-site interference mitigation. Establish performance goals of the approach. Provide a Phase II development approach and schedule that contains discrete milestones for product development.

PHASE II: Develop, demonstrate and fabricate a prototype as identified in Phase I. Using a 16-channel high power HF transmission system, in a laboratory environment demonstrate the ability to consolidate signals without significant loss of performance and the ability of the technology to reduce the effects of co-site interference. Demonstrate that the prototype meets the performance goals established in Phase I. Develop a cost benefit analysis and a Phase III installation, testing, and validation plan.

PHASE III: Working with government and industry, develop prototypes of final products identified in Phase II and perform tests to validate performance. Evaluations should be conducted on a shipboard test platform or at a representative Land Based Test Facility as appropriate and should demonstrate the ability to consolidate signals without significant loss of performance and the ability of the technology to reduce the effects of co-site interference.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Hand held radio manufacturers are in the market for technology that can permit more signals to be transmitted and received simultaneously through existing antennas.

REFERENCES:
1. John C. Kim and Eugen I. Muehldorf, Naval Shipboard Communications Systems, Prentice Hall, 1995.

2. Michael A. Maiuzzo, Shing T. Li, John W. Rockway, James H. Schukantz, and Daniel W. Tam, "Comb Linear Amplifier Combiner (CLAC)," Patent 6,211,732 Issued 3 April 2001.

3. Michael A. Maiuzzo, Shing T. Li, John W. Rockway, James H. Schukantz, and Daniel W. Tam, "Comb Linear Combiner for Frequency-Hopped Communications," Patent 6,549,560 Issued 15 April 2003.

4. Richard Adams, Ted Harwood, Mike Maiuzzo, "An Innovative Signal Distribution System that Allows EMI Free Communications for Navy Ships," presented at 2008 MILCOM conference.

KEYWORDS: HF Communications; antenna combiner; automatic link establishment; co-channel isolation; passive intermodulation; co-site interference

** TOPIC AUTHOR (TPOC) **

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