Smaller aerials for eLoran transmitters
A US patent will see Loran LF antenna towers significantly lower in height than previously needed for identical coverage.
Last month saw the Continental Electronics Corporation (CEC) granted a patent by the US Patent and Trademark Office (USPTO) in the name of the CEC Senior Scientist. The patent covers a transmitter system and method that will enable the construction of LF antenna towers significantly lower in height than previously needed for identical coverage.
The CEC Vice President comments: 'One of the obstacles to deploying eLoran systems has been the sheer height needed for the transmission towers, each of which requires significant real estate acreage. The tower height and land required not only represent serious financial costs, but in some cases adequate space is simply not available. Our technology can directly reduce the tower height and the real estate requirements. For example, by utilising this system and method, reducing the antenna tower height by half would reduce the land area required to one quarter.'
The system and method described in the patent use digital adaptive correction, solid state amplifiers, envelope modulation and a wideband matching network to achieve these results. Any linear distortions within usable bandwidth are removed by digital adaptive correction. Solid state amplifiers offering high efficiency, high reactive power capability and the ability to return the reactive power to the DC power supplies, are used to amplify the signal. Envelope modulation is required to achieve linearisation for any signal type - including Loran. A wideband matching network is employed to tune out capacitive reactance from electrically short antennas, transform the antenna impedance to a value suitable for the transmitter, increase usable bandwidth and suppress harmonics and out-of-band emissions.
The Vice President adds 'We hope that this new development will aid in moving forward eLoran deployments around the world. Widely used satellite-based navigation and timing services are vulnerable to jamming, spoofing and other forms of interference. The world needs a more resilient solution as afforded by ground based solutions such as eLoran.'
Details from CEC link below . .