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Ultra-Wideband Transmission Using Sub-wavelength Antennas on Airborne Platforms

Description:

TECHNOLOGY AREA(S): Info Systems 

OBJECTIVE: Develop the ability to transmit ultra-wideband radio signals from subwavelength antennas on airborne platforms. 

DESCRIPTION: Radio transmission is an important part of information transfer and critical for military operations during both peacetime and conflict. Antennas for radio transmission typically increase in physical size with wavelength but physically small antennas are highly desirable for airborne platforms. As result, classic transmitting antennas become problematic for lower frequencies on airborne platforms. Electrically small antennas can be used but they have very limited bandwidth, large matching and tuning elements and power limitations [1]. Furthermore, it is increasingly desirable to use ultra-wideband signals which can provide high data rate, low probability intercept and anti-jam communications capability. However, with the exception of highly inefficient antennas, ultra-wideband electrically small antennas these are not available with today’s technology. This topic is intended to examine new and innovative techniques for radiating ultra-wideband signals from electrically small antennas on airborne platforms. The limits for classic electrically small antennas are well known and fundamental [1]. However, there are emerging techniques using non-linear or time varying antenna and tuning elements that have the promise of overcoming these limits and thus enable transmission of ultra-wideband signals from electrically small antennas [2, 3, 4, 5]. These techniques use non-linear or time varying antenna elements and/or tuning & matching systems. This emerging technology has the potential to enable the use of small ultra-wideband antennas on airborne platforms with nearly zero cross section. 

PHASE I: The approaches described in the literature for developing ultra-wideband transmitting antennas will be examined and the most promising technique selected. Rigorous modeling, analysis and simulation will be used to develop an understanding of the relationship between the critical parameters for the selected approach. These include but are not limited to the length and shape of the antenna and voltage limits. The availability of non-linear time varying elements will be determined and the relationship of the critical parameters to the desired signal bandwidth will be explored. The objective is to design a demonstration model to validate the approach chosen at low power. This phase will include investigation into the possibility of combining non-linear time varying technology with different shaped antenna elements. 

PHASE II: During this phase a scale model prototype of the ultra-wideband transmitting antenna that would be suitable for use on an airborne platform will be constructed and tested. The frequency band and waveforms of interest will be selected based on Air Force input. The signal formats selected will be transmitted and received during this test. These signals would be received at terrestrial locations for analysis. As part of Phase II, the fundamental limitations for this technology will be explored especially in terms of the transmitting hardware needed to enable this technology for use in various airborne applications. The conclusion will be a recommended way forward for development of this technology. 

PHASE III: The ability to transmit an arbitrary wideband waveform from an electrically small antenna will be extremely useful for many military and civilian applications. During phase III a prototype system will be constructed based on the results of Phase II and tested in laboratory and flight test environments. The design will be refined based on the test outcome and customer feedback. 

REFERENCES: 

1. Hansen, R.C., Electrically Small, Superdirective, and Superconducting Antennas, Wiley, 2006; 2. Yao, Weijun Yuanxun Wang, “Direct antenna modulation - a promise for ultra-wideband (UWB) transmitting”, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535), 6-11 June 2004; 3. R. Janaswamy, Time varying antennas for enhanced bandwidths, 2014 IEEE Antennas and Propagation Society International Symposium, 2014, doi:10.1109.APS.2014.6904641; 4. Daly, E. L., Bernhard, J. T., & Daly, M. P. (2016). Synchronously tuned patch for transmitting FSK. In 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016 - Proceedings (pp. 2147-2148). [7696780] Institute of Electrical an

KEYWORDS: Ultra-Wideband Radio Transmission, Electrically Small Antennas, 

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