C. Zhang, S. Yang, H.K. Pan, A.E. Fathy, S. El-Ghazaly, and V. Nair (USA)
Reconfigurable Antennas, Universal Receivers, Multi Band Antennas. Furthermore, we have been very active in developing another viable option, a reconfigurable antenna system shown in Fig. 1d. We have developed a nested-patches antenna designed to cover one band at a time, which has recently been pushed even further in development of a much smaller version: the mini-nested-patches antenna. The mini-structure was developed in a way that simplified the feed, kept the gain and radiation pat
Extensive efforts are currently underway to develop universal wireless receivers to address multi-band, multi service, and multi-standard operation. While there are many options for the design of the RF front-end, there are only four options for the design of the associated antennas. Antenna options include the use of: separate function, wide band, multi-band, and reconfigurable antennas. Reconfigurable antennas, however, would have potential in providing such great versatility, offering a compact size, low cost, and high performance. Nevertheless, they have certain limitations, including the presence of higher order resonances (spurious resonances) and the need to simultaneously serve multiple services at the same time, but these impediments can be easily circumvented. c d Fig 1 Different topology alternatives for multi-standard, and multi band receivers: a) Use of separate receivers, one for each service, b) Wide band receiver where high Q filters are required, c) Multi band design where performance is optimized at selected bands, d) reconfigurable antenna to receive one service at a time.Relatively wide band filters could follow/cascade these reconfigurable antennas to eliminate any spurious higher order resonances and block out their associated added noise. The use of these filters typically adds minimal insertion loss, but they would drastically reduce the stringent requirements of the currently used expensive RF front-end filters. The use of reconfigurable antennas developed for switchable services can be extended to allow mixed services (i.e. providing more than one service at one time). The first alternative is a simple straightforward architecture that utilizes separate receivers and antennas, one for each service (Fig. 1a). Obviously, such an option requires a large amount of real estate, has many redundant components, and can be relatively expensive. The second alternative is a wide band antenna, an appealing alternative (Fig. 1b) as it would only require one antenna followed by a bank of highly selective filters to reduce the effect of relatively high input noise. The third alternative is a multi-band antenna approach and is now very popular, as it could offer considerable rejection of out of band noise; thus reducing the required filter specifications and its associated cost (Fig. 1c).
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