A miniaturization technique of a compact omnidirectional antenna

This paper discusses a miniaturization technique of a compact omnidirectional antenna. A slot loading technique is applied to a well-know low-profile antenna structure whose radiation characteristics are similar to equivalent monopole ones. The typical dimensions (width times height) of the obtained antenna are lambda₀/11timeslambda₀/75 (lambda being the free space operating wavelength) which makes it a miniature antenna that can be integrated inside small wireless sensor nodes using narrow band communication systems. Its performances are in accordance with classical fundamental limits, the operating bandwidth and efficiency are significantly reduced with the antenna miniaturization.