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Compared to the traditional monostatic MIMO radar which uses uniform linear arrays (ULAs) for transmitting and receiving signals, sparse linear arrays (SLAs) monostatic MIMO radars can achieve greater Degrees Of Freedom (DOF) and a higher resolution. The optimal placement of sensors in both transmit and receive arrays to attain the maximum DOF is, however, a basic problem in the collocated monostatic MIMO radar. Optimum solution of such a problem is restricted to an exhaustive computer search. Some popular arrays such as nested and coprime arrays have been previously proposed as alternative solutions that can achieve a good DOF, but they do not necessarily lead to the maximum one. In this paper at first, we formulate the optimal placement of sensors in the collocated monostatic MIMO radar to improve the sum coarray as well as the difference coarray of the sum coarray. After that, we present a mathematical framework to achieve the optimal solution for both problems. Finally, we demonstrate that the proposed method yields the optimal MR-MIMO array while demanding much less computational complexity as compared with the computer search. [ABSTRACT FROM AUTHOR]

This paper proposes a complete transmitter prototype for wireless applications using envelope tracked pulsed gate modulated power amplifier (PA). The proposed transmitter architecture is developed using two high power 10 W gate modulated PAs combined in a fashion to operate as a switched voltage source for the range of duty cycles of pulses driving the gates of power amplifiers. These PAs are designed and implemented using packaged GaN HEMT transistors from CREE to operate at the carrier frequency of 2.35 GHz. For a 5 MHz bandwidth WiMAX 802.16e down-link signal with the PAPR of 7.9 dB and the oversampling ratio of 100, the average drain efficiency of 46.2% is achieved at the average output power of 35.8 dBm. Using a 5 MHz bandwidth LTE down-link signal with 11 dB PAPR and centered at 2.35 GHz, the power amplifier delivers the average output power of 33.2 dBm with the average drain efficiency of 46%. The adjacent channel leakage ratio (ACLR) measured for this signal is less than -36.85 dBc at 10 MHz offset from the center frequency of 2.35 GHz. [ABSTRACT FROM AUTHOR]