Abstract-This paper focuses on a tutorial overview of defected ground structure (DGS). The basic conceptions and transmission characteristics of DGS are introduced and the equivalent circuit models of varieties of DGS units are also presented. Finally, the main applications of DGS in microwave technology field are summarized and the evolution trend of DGS is given.

Abstract:The problem of finding link/node-disjoint paths between a pair of nodes in a network has received much attention in the past. This problem is fairly well understood when the links in a network are only specified by a single link weight. However, in the context of Quality of Service routing, links are specified by multiple link weights and restricted by multiple constraints. Unfortunately, the problem of finding link/node disjoint paths in multiple dimensions faces different conceptual problems. This paper presents a first step to understanding these conceptual problems in link-disjoint Quality of Service routing and proposes a heuristic link-disjoint QoS algorithm that circumvents these problems.

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Abstract-Retrodirective arrays have garnered much attention due to the unique feature of automatically responding to an interrogator without any prior knowledge of the location of the incoming signal. This paper describes the basic concept of retrodirective array technology, discusses the three retrodirective array topologies with their advantages and disadvantages. Characterizations of the selfsteering performance in a retrodirective antenna array are described. A series of array design considerations in the retrodirective array systems is presented, and further researches in this area are presented.

Abstract-This paper presented a novel dual band transmitter which operates as power amplifier or frequency doubler with the stop band characteristic of defected ground structure (DGS). It works as a power amplifier at 2.4 GHz which satisfies the 802.11b/g wireless LAN standard or performs as an active frequency doubler at 6.8 GHz which depends on the input frequency and. The equivalent circuit and the stop band characteristic of the proposed microstrip DGS are analyzed and simulated. For the proposed transmitter, second harmonic suppression is below −52.6 dBc in the amplifier mode, and fundamental suppression is below −41 dBc in the frequency doubler mode with the stop band characteristic of DGS. The designed transmitter used GaAs InGaP Heterojunction broadband MMIC. It achieves 13.7 dBm of P 1 dB and its gain is 16.5 dB in amplifier mode, and its maximum output power is 7.8 dBm at 6.8 GHz in frequency double mode.