Harman Kardon
In 1959, Harman Kardon marketed the Citation II, an early ultra wideband stereophonic tube amplifier. Designed by Stewart Hegeman, it featured 60 watts/channel output with a frequency response of 18-60,000 Hz at 20 watt output. The company promoted their philosophy of designing high fidelity sound using amplifiers that provided widest possible audio bandwidth. Although the human ear highest audible range is around 20,000 Hz, the full range of sound goes beyond that with harmonics and overtones that may be beyond the hearing range of the human ear. These harmonics interact with other frequencies to produce audible secondary sounds or interference. Harman Kardon promoted the design in audio magazines and product brochures.
Radio Gaúcha AM Guaíba Mast
The Radio Gaúcha AM Guaíba Mast (also known as IPÊ Mast or as Antena do Parque Técnico Maurício Sirotsky Sobrinho) is the tallest man-made object in Brazil. The Radio Gaúcha AM Guaíba Mast is used by Radio Gaúcha for medium-wave broadcasting on 600 kHz with 100 kW. The mast is located in the city of Guaíba, in the metropolitan area of Porto Alegre, state of Rio Grande do Sul, at . It is a 230-metre (755 ft.) tall, ground-insulated guyed mast radiator, and a nearly perfect replica of Warsaw Radio Mast. The Radio Gaúcha AM Guaíba Mast was built in 1985/1986 to improve the transmissions of football matches.