Design of High Frequency Surface Wave Radar Receive Monopole Array Elements

Beamforming offers advantages over direction finding as a configuration for receive antennas in high frequency surface wave radar (HFSWR) applications. On the other hand are considerations of the large array size, as well as electrical, mechanical and environmental matters. The latter are particularly onerous with the harsh Newfoundland weather, and corrosion from continual salt spray. The Radar Remote Sensing Laboratory (RRSL) recently rehabilitated its Argentia high frequency surface wave radar (HFSWR) receive array. The new elements being shorter than a quarter wavelength, exhibited large capacitive reactance, reducing the efficiency at which the received signal could be transferred to the transmission lines. More importantly was the potential to perturb the beamforming by introducing non-uniform reactances amongst the elements. To address these problems, the element feedpoint impedance was estimated from transmission line theory and used to solve the conjugate match solutions of the well-known' <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$L$</tex> ' network. An attractive solution offers easily reproducible tuning and a DC ground to safely discharge static. Mechanical constraints and environmental considerations were implemented followed by extensive field testing with a vector network analyser. The most recent iteration of the design was drafted and constructed by Memorial University's Technical Services division. We outline the derivation of the network design and practical elements of its construction and implementation.