In this paper, we discussed about the work done by researchers for the enhancement of performance of a multiband BPF by introducing different defected ground structure (DGS) geometries. A DGS structure on a conventional inductively coupled band pass filter is used to miniaturize the resonator. By introducing a DGS on the transversal dimension of the CPW, it enhances filter performance. The DGS cell also transforms a single band to a multiband BPF by using this structure. The design technique of the filters with the DGS can be explained at very high frequencies in GHz ranges and give very accurate simulated and measured results.

This paper introduces the elements of the Worldwide Interoperability for Microwave Access (WiMAX) innovation and future utilizations of WiMAX. It is a connection oriented wireless network that assures Quality of Service (QoS) for all users in the network. By comparing WiMAX with the popular Wi-Fi, 3G and LTE in the market, it analyzes the current situation and future development trend of WiMAX in terms of the difference in technology and applications. WiMAX will become the most prominent technology for Broadband Wireless Access (BWA). The next generation WMAN networks, using the WiMAX as the core technology is evolving as a 4G technology for providing ubiquitous computing solutions. In not a similar way like wireless LANs, WiMAX networks integrate various QoS mechanism at the Media Access Control (MAC) level for secured service for voice, data and video. The unique architecture of the WiMAX MAC and PHY layer that uses OFDMA to allocate multiple channels with different modulation schemes. A few references have been incorporated towards the completion of this paper for those eager to know in brief about certain points.

In this paper a multi frequency U-slot patch antenna for wireless applications is presented. The proposed antenna operates at four frequencies of 1.4GHz, 5.3GHz, 6GHz and 6.9GHz with return loss of -19dB, -22.50dB, -21.05dB, -19.37dB respectively. The antenna is designed with Rogers R04232 substrate with dielectric constant of 3.2 and dielectric loss 0.043 with dimensions of 47 × 54 × 1.5 mm3. Coaxial feed technique is used as a feed to the antenna which is having characteristic impedance 50 ohm. The simulation studies were carried out using Ansys HFSS 15.0 Software.

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