Antennas WWVB

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the wwvb signal transmitted via phased array of 2 identical antenna systems, spaced 2,810 feet (857 m) apart, 1 of used wwvl. each consists of 4 400-foot (122 m) towers used suspend top-loaded monopole (t-aerial), consisting of diamond-shaped web of several cables in horizontal plane (a capacitive top-hat ) supported towers, , downlead (vertical cable) in middle connects top-hat helix house on ground. in configuration, downlead radiating element of antenna. each helix house contains dual fixed-variable inductor system, automatically matched transmitter via feedback loop keep antenna system @ maximum radiating efficiency. combination of downlead , top-hat designed replace single, quarter-wavelength antenna, which, @ 60 khz, have impractical 4,100 feet (1,250 m) tall.


as part of wwvb modernization program in late 1990s, decommissioned wwvl antenna refurbished , incorporated current phased array. using both antennas simultaneously resulted in increase 50 kw (later 70 kw) erp. station became able operate on 1 antenna, erp of 27 kw, while engineers carry out maintenance on other.








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