H-field antenna considerations for eLoran aviation applications

The U.S. Department of Homeland Security has designated enhanced Loran (eLoran) as a backup for the Global Positioning System and will pursue development and delivery of eLoran services to aviation, maritime, and time and frequency users. Many of the improvements, much of the analysis, and the operational modifications necessary to transition the current Loran system to eLoran have been established in the process of modernizing Loran. However, new performance standards and approval test procedures are needed for certifying eLoran avionics. More specifically, for aviation applications, precipitation static (p-static) has historically been a significant interference effect for Loran when E-field antennas have been used and was the primary reason why Loran-C could not support the approach and landing phase of flight. However, research conducted over the last decade clearly indicates that by using an H-field antenna the effects of p-static for Loran applications can be mitigated. This work begins the specification process for an eLoran H-field antenna that may be suitable for a Minimum Operation Performance Specification (MOPS). This paper presents a number of considerations for the design, installation, and use of an H-field antenna in eLoran aviation applications and puts forward parameters for specification, proposed values, configurations, and test methodologies. The objective of this paper is to present various considerations and options for an eLoran H-field antenna performance specification to stimulate discussion within the Government, industry, and academic position, navigation, and time communities and to receive feedback in the specification process.