Small, tunable FM antenna: US Pat. No. 7,642,983

U.S. Patent No. 7,642,983, issued on January 5, 2010 to PowerQ Technologies, Inc. of Irvine CA, discloses a ferrite antenna which can be automatically tuned for optimal performance with various FM frequencies.

FM antennas are conventionally “quarter-wave” antennas, in which the length of the antenna is approximately equal to one-quarter of the wavelength of the signal (e.g., about 31 inches for a 100-MHz FM signal).  However, this size may be inconvenient to use in certain circumstances (e.g., a handheld device).  Also, for automobiles having various added-on devices which receive real-time information on FM frequencies (e.g., for navigation, traffic, gas price), it may be undesirable to have to modify the car’s internal wiring to access the FM radio antenna, and such sharing of the antenna may result in additional noise to the car radio.

The patent discloses a small, tunable antenna using a ferrite core (e.g., a rod about one inch in length or a flat disk about 1.5 inches wide), a single-turn tuning coil, and a multi-turn pick-up coil to receive FM signals.  Such an antenna avoids the length of a quarter-wave antenna and allows separate devices to include their own antennas.   

PowerQ provides products for both consumer applications (PowerHD 100 antennas for receiving digital television broadcasts) and for military applications.  Besides the ’983 patent, PowerQ is currently listed in the public USPTO database as the assignee of two other patents in the area of amplifier circuits and methods.  According to their website, PowerQ is “diligently securing for the Company, certain ownership rights of key technologies.”