Dual-frequency air-spaced patch antennas

  • R.N. Foster, P.S. Hall, E.G. Hoare
  • January 2008, the Institution of Engineering and Technology (the IET)
  • DOI: 10.1049/ic:20080099

Patch antennas operating at two frequencies without a substrate

What is it about?

Patch antennas are a type of printed circuit antenna - typically rectangular or square, but also often circular, or triangular. The patch can be modified to allow it to work at more than one frequency, such as by placing slots (regions of no metal) within the patch. The printed circuit board ("substrate") introduces losses that are of increasing significance at higher frequencies, where power generation is limited and atmospheric absorption increases. This paper looks at the use of "air-spaced" patch antennas (so, no substrate but air) and the use of two methods for introducing dual frequency operation. The air substrate means the patch must be supported with thin metal strips, which modify the effect of conventional methods for achieving multiple frequency operation.

Why is it important?

When this was published, it was a prototype for millimetre-wave antennas at 60-80 GHz, suitable for dual function automotive radar and telematics antennas. Technology has progressed to the point that the challenges explored here are now being faced at frequencies 300 GHz and above, but the solution explored is still relevant.


Dr Robert N Foster
University of Birmingham

This was a conference paper that presented the results for two types of dual frequency patch: an offset stub-loaded patch, that took advantage of the support struts to achieve operation at two frequencies, and a slotted patch, that looked to achieve different frequency ratios and kept the support stubs at the minimum impact point.

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The following have contributed to this page: Dr Robert N Foster