Center for Remote Sensing, Inc.

Yoonjae Lee

Suman Ganguly

Raj Mittra

An antenna having multiple antenna elements of unequal lengths, form in a conical shape. The longest antenna element has a trap in a specific location of the antenna element. Multiple traps can be used for extended coverage depending upon the frequency band. The antenna elements are connected together through a transversal-wire ring and a feed transmission line is attached to it. The antenna occupies minimal footprint in the horizontal direction and maintains a low VSWR and a uniform beam pattern over a wide frequency band, more than 1:20. The antenna has a constant radiation pattern over a 1:6 bandwidth and the pattern bandwidth may be increased using more antenna elements and traps. The elevation and azimuth patterns show a consistent characteristic from 100 MHz to 600 MHz.

Compact broadband antenna with constant radiation pattern

A multifrequency antenna comprising a stack of nonconductive substantially planar substrates, with a conductive layer disposed on each substrate surface. A first substrate includes transmission lines disposed on a rear surface and a conducting layer on the other surface. A second substrate is stacked on the first substrate. A conducting layer is disposed on one side of the second substrate surface. Conducting layers disposed on first and second substrates include a plurality of slotted openings arrayed about an antenna axis. A third substrate stacked on the second substrate includes a conducting layer top. A lossy dielectric-magnetic material encloses sides and rear of the multifrequency antenna, to prevent electromagnetic energy penetration through the enclosure. An edge diffraction suppresser reflector is attached in the rear surface of the multifrequency antenna, and has two or more essentially circular, conducting plates and a multitude of conducting cylinders along the axis of the multifrequency antenna.

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Fairfax Station, VA, United States of America

Yoonjae Lee