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Vehicle roof mounted slot antenna with separate AM and FM feeds

  • US 4,721,963 A
  • Filed: 07/25/1986
  • Issued: 01/26/1988
  • Est. Priority Date: 07/25/1986
  • Status: Expired due to Term
First Claim
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1. Slot antenna apparatus for a motor vehicle comprising, in combination:

  • a vehicle body made of an electrically conducting material and having a lower body portion, a plurality of vertical pillars defining window openings and a horizontal roof portion with a central portion made of electrically non-conducting material;

    a horizontal sheet of electrically conducting material attached to the roof portion, the horizontal sheet including a looped slot adjacent the central portion of the roof portion dividing the sheet into inner and outer portions, the slot having a total loop length of substantially one wavelength in the commercial FM broadcasting band;

    FM feed means connected to the inner portion of the horizontal sheet at the front center of the slot to provide signals in the commercial FM band to FM receiver apparatus;

    AM feed means connected to the inner portion of the horizontal sheet at the side center of the slot essentially 90 degrees rotated from the front center of the slot to provide signals in the commercial AM band to AM receiver apparatus; and

    means effective to ground the outer portion of the horizontal sheet to the vehicle body at DC and at radio frequencies in the commercial AM and FM bands.

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