SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  N102-159 (Navy)
Title:  Consolidated Apertures with Co-site Interference Reduction in the Frequency Range 2 to 30 MHz
Research & Technical 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

Questions and Answers:
Q: How will the acceptability of novel antenna designs be assesed for existing ship designs (e.g. DDG-51, CVN, LPD-17) with regards to co-site performance and impact on overall topside design?
A: I expect that nothing will be done to the antennas. All of the improvements should be done by electronics on the signal before it reaches the antenna. Typically the HF antennas are going to be large.
It is also difficult to make an antenna that is efficient for transmit in a 15:1 frequency range. Antennas in the higher range (say 7 to 30 MHz) must have the ability to launch a horizontally polarized wave to the ionosphere and later a vertically polarized wave to the horizon.
They must be omni-directional and have the ability to withstand high power and have a maximum VSWR of 4:1 in their appropriate frequency range. Typically HF antennas irradiate the whole ship structure.
Q: 1. What is the output power an each frequency, and the duty cycle?

2. Does the new device have to adaptively match to the antenna at each frequency band segment, or is the impedance vs frequency of the antenna predictable?

3. What is the minimum separation between frequencies?

4. Do the transmitters hop, and if so what is the fastest hopping rate?
A: The output power is governed by OPNAV Instruction 2300.44G. For a DDG class ship in the 2 to 30 MHz range, the system must be able to handle 4 500 W and 4 100 W transmit signals while receiving 12 simultaneously.

The system must be scalable to be able to handle larger communications requirements for ships such as the CVN or LHD. For the CVN the system must handle 6 500 W and 7 100 W while receiving 18 simultaneously. For an LHD or LHA the system must handle 8 500 W and 6 100 W signals while receiving 20 signals simultaneously. The duty cycle is 100%.
The system must match the antenna for each range. The maximum VSWR is
4:1 over the entire 2 to 30 MHz range.

The minimum frequency separation is a figure of merit. The legacy is 5% frequency separation. We want bettter.

The transmitters change frequency at a slow rate to accommodate the environment. This is characteristic of Automatic Link Establishment.
Legacy systems change frequency at a rate of about 2 hops per second.
Q: What are the goals for (TX) power handling capability, insertion loss, and minimum received signal strength for the final system?
A: The maximum power should follow the requirements of OPNAV Instruction 2300.44G. In the 2 to 30 MHz for a DDG class ship, the system must handle 4 500 W and 4 100 W signals while receiving 12 signals simultaneously. The system must be scalable so that it can handle the communications needs of a CVN. The requirements for a CVN are 6 500 W and 7 100 W while receiving 18 signals simultaneously. An LHD or LHA must handle 8 500 W, 6 100 W signals while receiving 20.

Standards for insertion loss involve doing better than legacy. The proposals will be judged on this figure of merit. My objective is a maximum insertion loss of 2 dB per signal when combining up to 14 transmit signals.

The minimum received signals is governed by the environment. There are standards for the quasi-minimum noise spectrum which depends sensitively on frequency.

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