Ascom Tech Ag

Ulrich Dersch

Matthias Liebendoerfer

A flat three-dimensional antenna is built in three planes. In the first plane is a base plate, in the second plane is a slot divider bent in a U-shape, and in the third plane is resonant structure above the slot divider. The slot divider has a middle part with a length of preferably .lambda./4 and two limbs of .lambda./8 of the same length. With the base plate the slot divider forms a .lambda./2 antenna slot, while the resonant structure with the slot divider defines a shorter second antenna slot. The antenna is characterized by a large bandwidth and omnidirectional radiation characteristic. Perpendicular to the base plate there is essentially no radiation. Feeding takes place preferably via a stripline which is routed between two limbs to a middle part. Impedance matching of the antenna is achieved by suitable dimensioning of the stripline. The antenna can be built equally well in air as well as in a dielectric such as a ceramic block. Several of these antennas can be combined into an ultracompact diversity antenna system.

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Wohlenschwil, Switzerland

Ulrich Dersch