C. C. Tripathi

Design of compact reconfigurable switched line microstrip phase shifters for phased array antenna

Wireless communication systems are evolving toward multifunctionality. This multi functionality and reconfigurability provides users with options of connecting to different kinds of wireless services for many purposes at different times by providing additional degrees of freedom in the system e.g. cognitive radio, MIMO systems and high performance phased arrays. Although Phase shifters are important component in many RF microwave subsystems e.g. radar, phased array antennas, beam forming networks, frequency translators yet the reconfigurable phase shifter provides additional degree of freedom in these systems by reconfiguring the phase shift at a given frequency. In this paper design and simulation of reconfigurable switched line phase shifter for phased array antenna using Ansoft HFSS 14 is presented. The reconfigurability is achieved by loading phase shifter using high frequency PIN diodes which acts as microwave switches. A compact reconfigurable phase shifter has been designed which gives a very low insertion loss ≈ -1 dB and wide range of linear reconfigurable phase shift over frequency from 1 to 5 GHz. The designed phase shifter gives reconfigurable phase shift for different application i.e. at 1.8 GHz (GSM), 2.4GHz (Wi-Fi), 3GHz (traffic control and collision avoidance radars), 3.6GHz (WLAN) by appropriate settings of the 8 switch positions. As designed phase shifter can be used for 3600 beam steering in phased array antenna.

Cognitive Radio: An efficient and effective solution for future spectrum implications

The paper presents an exhaustive visualization of different problems encountered in efficient utilization of spectrum for advanced wireless communication. It is a well known fact that there is a crisis for available radio spectrum due to incredible expansion and advancement of the communication systems and technologies. But in reality, there is no shortage of available spectrum but only lack of advance techniques for perfect utilization of spectrum. So, to tackle the future spectrum implications, the new emerging field of Cognitive Radio is explored here. Cognitive Radio has potential to revolutionize the way of spectrum allocation scheme worldwide because it can recognize spectrum condition and reconfigure itself to optimize its operation to compete with growing demands of the spectrum. In this paper, complete description and working operation of Cognitive Radio is presented. The paper provides special emphasis on various aspects of Cognitive Radio like different spectrum sensing methods and spectrum sharing schemes with the appropriate mathematical formulation. To facilitate implementation of this idea, new design requirement on antennas features is thoroughly explained here.