Cross slot omnidirectional antenna

DETAILED DESCRIPTION What is claimed is: 1.
An antenna for radiating radio frequency energy at preselected frequency comprising: a hollow member having thin conductive walls, said member being four way symmetric about a vertical axis and having a maximum horizontal dimension of less than one wavelength at said preselected frequency, said member having a plurality of horizontal slots having lengths less than two-thirds of a wavelength at said preselected frequency, said slots spaced vertically in two rows, each row centered on a point of maximum horizontal dimension, and said two rows spaced symmetrically about said vertical axis, forming vertically stacked pairs of cross slot radiating elements, power divider means having an input for receiving RF energy at said preselected frequency and one output for each of said slot radiating elements and means for coupling RF energy from said power divider means to said slots to be radiated, whereby said RF energy is radiated in an omnidirectional pattern.
2.
An antenna according to claim 1 wherein said power divider means is housed within said hollow member.
3.
An antenna according to claim 2 wherein said power divider means is a stripline network.
4.
An antenna according to claim 3 wherein said power divider means includes phase shifter means for providing preselected phase shifts to preselected pairs of slot radiating elements, whereby the radiated RF energy is directional in the vertical while remaining omnidirectional in the azimuth.
5.
An antenna according to claim 4 wherein the stripline network is rectangular and has a width substantially equal to said maximum horizontal dimension of said hollow member, said network positioned vertically within said hollow member with its edges aligned with the centers of said two rows of slot radiating elements, said network including exciting probes along its edges for coupling RF energy into said slot radiating elements.
6.
An antenna for radiating radio frequency energy at a preselected frequency comprising: four identical rectangular conductive sheets each having a width of less than 0