This paper presents a complex microstrip patch antenna design for Ku-band satellite communication applications. FR4 and RogerRT6002 have alternatively been used as substrates having dielectric constant of 4.4 and 2.94 respectively. The patch ground and feedlines are made of copper. The proposed antenna is unique in shape with rectangular slots. The performance of the antenna has been analyzed in terms of far field gain. The most significant results were obtained using FR4 substrate, which gave a gain of 7.88 dB, at 11.32 GHz and a reflection coefficient of-10.48 dB. The final microstrip patch antenna design was simulated, built and tested. Simulated and measured S11 frequencies perfectly match at 11.32 GHz with simulated and measured magnitudes of-10.48 dB and-29.64 dB respectively.

The paper considers an underlay cognitive radio model, which includes multiple primary and secondary users. Under the interference limitations imposed for the conservation of a high quality of service (QOS) for the primary users, this work aims to enhance the throughput of the secondary users. A joint optimization of secondary to primary user assignment and the power allocation at the secondary user's transmitters is adopted under the interference as well as individual power constraints. To solve the formulated integer programming problem, dual decomposition strategy is adopted. KarushKuhnTucker (KKT) optimality conditions are exploited to obtain the optimal power allocation while user pairing is obtained from the assignment problem. Moreover, sub-optimal schemes are proposed to reduce the complexity and finally simulations are conducted to validate the proposed schemes.

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