International audienceAn air-filled substrate integrated waveguide (SIW) made of a multilayer printed circuit board process is proposed in this paper. It is of particular interest for millimeter-wave applications that generally require low cost and low-loss performance and excellent power-handling capability. This three-layered air-filled SIW allows for substantial loss reduction and power-handling capability enhancement. The top and bottom layers may make use of a low-cost standard substrate such as FR-4 on which baseband or digital circuits can be implemented so to obtain a very compact, high-performance, low-cost, and self-packaged millimeter-wave integrated system. Over Ka-band (U-band), it is shown that the air-filled SIW compared to its dielectric-filled counterparts based on Rogers substrates RT/Duroid 5880 and also 6002 reduces losses by a mean value of 0.068 dB/cm (0.098 dB/cm) and 0.104 dB/cm (0.152 dB/cm), increases average power-handling capability by 8 dB (6 dB) and 7.5 dB (5.7 dB), and quality factor by 2.7 (2.8) and 3.6 (3.8) times, respectively. The peak power-handling capability of the proposed structure is also studied. A wideband transition is presented to facilitate interconnects of the proposed air-filled SIW with dielectric-filled SIW. Design steps of this transition are detailed and its bandwidth limitation due to fabrication tolerances is theoretically examined and established. For validation purposes, a back-to-back transition operating over the Ka-band is fabricated. It achieves a return loss of better than 15 dB and an insertion loss of 0.6 ±0.2 dB ( 0.3 ±0.1 dB for the transition) from 27 to 40 GHz. Finally, two elementary circuits, namely, the T-junction and 90 ° hybrid coupler based on the air-filled SIW, are also demonstrated

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This article introduces the design of a small (30 mm × 35 mm × 1.6 mm) band‐rejected U‐slotted planar antenna on FR4 substrate having a relative permittivity of εr = 4.4 for Impulse Radio Ultra Wide Band (IR‐UWB) systems. The antenna is fed by a microstrip line and rejects the frequency band from 5.15 GHz to 5.825 GHz used by IEEE 802.11a and HIPERLAN/2. This antenna shows good characteristics for IR‐UWB. The effects of variation on steps and U‐Slot are discussed. The antenna is characterized both in the time and frequency domains by use of simulation and measurement.© 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1727–1731, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22515