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This paper investigates the performance of the single slot ring element for Ka-band reflectarray designs. Using the element rotation technique, two Ka-band circularly polarized reflectarray prototypes are designed and implemented, with different thicknesses of the substrate. The bandwidth is significantly enhanced when a thick substrate is used.
Orthogonal frequency division multiplexing (OFDM) with dynamic scheduling and resource allocation is a key component of most emerging broadband wireless access networks such as WiMAX and LTE (long term evolution) for 3GPP. However, scheduling and resource allocation in an OFDM system is complicated, especially in the uplink due to two reasons: (i) the discrete nature of subchannel assignments, and...
A production ready pseudomorphic high electron mobility transistor (pHEMT) using i-line 0.25 mum optical gate lithography has been developed for both Ka- and Ku-band power applications. These 0.25 mum Ka- and Ku-version pHEMT devices demonstrate state-of-the-art power performance at 29 and 10 GHz, respectively. Excellent reliability has been achieved at channel temperature exceeding 275degC. Yield...
This paper presents a low-cost wafer-level test methodology for the source driver ICs of liquid crystal displays; the idea is to realize the test circuitry on the wafer scribe line. The proposed technique not only substantially reduces the required ATE I/O channels but also eliminates the need of high-speed digitization units on the ATE. Furthermore, because the test circuitry is realized on the scribe...
Using split square ring elements and the modified element rotation technique, an X-band circularly polarized reflectarray is designed and implemented through microstrip technology. At 8.4 GHz, the reflectarray prototype has a gain of 30.4 dB and an aperture efficiency of 53.7%. The fractional axial ratio bandwidth is 6%, while the 3 dB gain bandwidth is 7%.
A new approach to the high performance missile autopilot design based on the nonlinear servomechanism theory is proposed. This approach coupled with the analytic gain scheduling leads to an effective means to account for the nonlinearity and uncertainty in the missile system.
Modern nonlinear servomechanism theory is adapted to cope with the hard nonlinearities inherent in the gun turret system. This is accomplished by approximating the backlash and Coulumb friction by well behaved functions, and then synthesizing a nonlinear controller based on the scheme of "feedback stabilization" and "feedforward steady state compensation". Simulations show that...
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