A novel thick ground plane is proposed as a support for a slot-coupled microstrip antenna and as a heat sink for an MMIC installed on the back plane of the active array antenna. A multi-layer structure of ground planes is also studied for the benefit of easy installation of MMICs. The influence of this thick metal ground plane with a mono- and multi-layer has been investigated in detail. Both measured and calculated results of VSWR and calculated results of the back lobe are shown in detail. The calculated results of VSWR agree well with the measurements. It is made clear that the thickness of the ground plane can be extended to twenty times that of the antenna substrate while maintaining the antenna's performance. An LNA composing an MMIC was developed, attached to the back of the antenna, and operated at 23 GHz. The measured results of this active element agree well with calculated ones and confirm the applicability of the novel design.

Cognitive radio, which utilizes the radio frequency spectrum efficiently by recognizing radio resource availability, is an attractive technology for overcoming the shortage of radio frequency. From the perspective of networking, cognitive radio technologies are also useful since they allow flexible network construction. This paper proposes base station networks using cognitive radio technologies. In order to achieve efficient utilization of the radio frequency spectrum and flexible network construction, we also propose a topology management and route control method for our proposed base station network. Our method shares the status of the wireless links along with topology information and establishes routes by using this information. Through simulation, we evaluate that our method significantly improves the throughput by efficient utilization of the radio frequency spectrum. Moreover, we demonstrate that our method works well when the size of the network gets larger.

Short backfire (SBF) antenna developed by H.W. Ehrenspeck is experimentally well-known to have high efficiency radiation characteristics in spite of its small size so far. Therefore this antenna is expected to be one of the candidates of single antennas and an element of array antennas for several types of communications. For example, this antenna has been proposed for shipborne antenna of INMARSAT-M system for maritime satellite communications. Although many efforts to analize and/or optimize this antenna has been made mainly experimentally, rigorous design procedure has not been almost established even now because of its complex configuration. In 1980, an approach to analyze this antenna was tried by Kawakami, H. and et al. which was the first attempt to obtain the theoretical characteristics by more rigorous process, however, from the view points of practical designing, the calculated values in their paper were insufficient because of the lack of strict numerical consideration. Upon the above circumferences, analysis of SBF antenna is performed in this paper by using method of moment with wire-grid model from the view points of establishing the design technique. This paper presents the analytical results of the radiation characteristics of this antenna and also the comparison with the experimental results. From this study, it can be noticed that the radiation characteristics of this antenna can be almost exactly analyzed and also there exists the good agreements between the theoretical and experimental results.

CR (Cognitive Radio) is a technology that can realize more intensive and efficient spectrum use through spatial and temporal utilization. In the context of mesh networks where each base station consists of heterogeneous multi-radio interfaces, packet switch in L2/L3 of each base station selects each radio interface and channel adaptively in order to take full advantage of all multiple heterogeneous interfaces. At first, this paper examines the achievable performance of the new packet switch schemes in mesh topology. Secondly, we investigate the potentiality of dynamic base station relocation approach in order to cope with the change of terminal traffic distribution, and show the impact of packet switch policy on dynamic base station relocation.