Abstract: A novel method and apparatus encodes a data signal (e.g., before wireless transmission) such that the encoded signal has Gaussian statistics and the transmitted signal exhibits virtually no signal structure. This approach represents a significant improvement over previous attempts, as no synchronization between the encoder and decoder is required and the linearity of the transfer channel is preserved. Implementations of systems, methods, and apparatus according to embodiments of the invention are disclosed wherein the encoded signal has a flat power spectrum, wherein different codes are assigned to different users, wherein compensation for phase shifts is performed, and wherein the design and/or construction of the implementation may be accomplished using various digital filtering architectures.
Abstract: A patch antenna is provided with one or more tuning strips spaced therefrom and RF switches to connect or block RF currents therebetween. When a control system for the antenna selectively connects and isolates RF currents between certain of the tuning strips and the patch, the tuning strips change the effective length of the patch and thus the antenna's resonant frequency, thereby frequency tuning the antenna electrically over a relatively broad band of frequencies. The control system includes circuitry for rapidly switching the antenna to a desired frequency with minimal delay and with superior isolation from the antenna, making it suitable for use in DAMA, TDMA, and other frequency hopping applications.
Abstract: A patch antenna is provided with one or more tuning strips spaced therefrom and RF switches to connect or block RF therebetween. When RF is connected between the tuning strips and the patch, the tuning strips increase the effective length of the patch and lower the antenna's resonant frequency, thereby allowing the antenna to be frequency tuned electrically over a relatively broadband of frequencies. If the tuning strips are connected to the patch in other than a symmetrical pattern, the antenna pattern of the antenna can be changed.