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The transverse operator method is used for the analysis of an open-ended rectangular waveguide, in particular as a radiating element. It is shown that the method allows a systematic formulation of problems involving discontinuities whether they are radiating or not. The numerical results concerning the admittance and power patterns of a waveguide aperture surrounded by an infinite conducting flange are compared to those available in the literature, and a good agreement is observed.

Abstract-A compact printed ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna with embedded structure is proposed. The proposed MIMO antenna consists of two coplanar waveguide-fed (CPW) antenna elements, and the element with smaller size is built in the radiator of the other element. Thus, the compact size, 30 × 22 mm 2 , is completely determined by the larger one, which makes the MIMO antenna have similar size to the conventional single UWB antennas. The antenna elements are fed perpendicularly to achieve superior isolation. A T-shaped parasitic stub, a pair of C-shaped slots, an extended Z-shaped stub and a rectangular slot are employed and each two structures filter the interference for one antenna element. The achieved rejection bands remain relatively stable over the stop-band frequencies and decline rapidly at cut-off frequencies. Thus, the proposed MIMO antenna obtains superior filtering performance. The proposed antenna is fabricated and measured. The measured results indicate that two antenna elements can operate in the impedance bandwidth larger than 3.1-10.6 GHz with notched bands of 5-6 GHz, and the mutual coupling is below −15 dB over the entire UWB frequency spectrum. The proposed MIMO antenna is a competitive candidate for UWB MIMO communication systems.

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A novel dual‐band slot‐antenna for WLAN applications is presented. The antenna is composed of two narrow slots fed by a microstrip‐line. In order to increase the impedance bandwidth of a narrow slot and keep its small size, a kind of stepped‐impedance (SI) slot is used. It has been investigated experimentally for its impedance bandwidth, radiation pattern, and gain over its operation frequency band. Result shows that the antenna has a 10% bandwidth from 2.25 to 2.53 GHz and a 15% bandwidth from 5.13 to 5.99 GHz. And a good radiation pattern and gain can be achieved over the frequency range. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1203–1204, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22395