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A technique is proposed to mitigate the unwanted effect of ground plane currents when an antenna is mounted on a printed circuit board (PCB). To demonstrate the concept a CPW fed monopole is integrated onto a relatively large PCB. In the first stage of integration, a microstrip to grounded CPW feedline is incorporated to avoid connecting the PCB and antenna ground directly. To reduce the flow of current onto the edges of the PCB, two pairs of quarter-wavelength stubs are then utilised. A prototype is manufactured and examined. To show how this method enhances the radiation characteristics, the radiation patterns of the antenna in both an isolated and an integrated scenario with and without stubs are compared.Introduction: Since the FCC has allowed licence-free usage of the spectrum from 3.1-10.6 GHz for low power short impulse ultra-wideband (UWB) applications [1], planar monopole antennas have been much studied in the literature [2][3][4]. They are low profile, light in weight, cost-effective and easy to manufacture and have wide impedance bandwidth and stable radiation characteristics. However, when mounted on a printed circuit board (PCB), their radiation characteristics degrade owing to the coupling between the antenna and the PCB. The current flowing onto the edge of the PCB contributes to the radiation and deteriorates the radiation patterns.In this Letter, the isolation between the antenna and the PCB is addressed. A CPW fed monopole antenna is integrated into a relatively large PCB to demonstrate the concept. Two pairs of quarter-wavelength microstrip stubs are utilised to reduce the flow of current onto the PCB edge. The proposed technique is examined for the European UWB mask, which is partly focused on the frequencies between 6-8.5 GHz [5]. However, the technique can also be used for a wider frequency range. A prototype of the antenna is fabricated and examined. Details of the proposed strategy together with the simulated and measured results are presented.

In this article, a novel integration concept is introduced for multiband antennas. An integrated wide–narrow band antenna is presented, which is composed of a shorted microstrip patch integrated to a coplanar waveguide fed ultrawideband monopole antenna. The patch is printed on the reverse side of the substrate using the monopole antenna as a ground plane. A prototype of the antenna is fabricated and verified. This antenna adds the possibility to operate in two of different standards or frequency bands at any given time. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 425–430, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24926

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