Abstract: A system is provided for enabling use of a password or PIN (personal identification number) to prove authority for access to a data base, where the PIN cannot be safely transmitted to a verifying authority. The PIN is entered into a calculating circuit which produces a TPIN (translated PIN) which can be safely transmitted to the verifying authority. The TPIN has fewer digits than the PIN to avoid a one-to-one correspondence of each PIN to each TPIN. For example, a six digit PIN may yield a three digit TPIN. The present time is also entered into the calculating circuit and an algorithm for generating the TPIN uses the present time, so for a given PIN the TPIN repeatedly changes.

Abstract: A microstrip patch antenna assembly (20, 52, 106) is formed of a patch radiator (24, 58) and a feed structure (26, 64) of microstrip feed elements (48, 50, 66, 68) disposed on opposite sides of a ground-plane element (22, 54) and spaced apart therefrom by layers (28, 30, 72, 74) of dielectric material. A single slot (108) or a pair of orthogonally positioned slots (44, 46, 82, 84) within the ground-plane element couples linearly or circularly polarized microwave power from the feed structure to the patch radiator. Additional radiators (60, 62) may be stacked above the foregoing radiator, the radiators being separated by further layers (76, 78) of dielectric material. A plurality of square-shaped raidators (58, 60, 62) may be employed for multiple-frequency operation in which case the radiator size and the thickness of dielectric material between the radiator and the ground-plane element establish a resonant frequency.

Abstract: An antenna system for an array antenna includes an array of radiators formed as patch antenna elements on a dielectric substrate, there being a shielding metallic sheet on a side of the substrate opposite the radiators. A further dielectric substrate and a bottom metallic sheet are disposed on a side of the shielding sheet opposite the radiators. An antenna feed system is disposed in the further sheet. Coupling devices such as orthogonal slots, in one embodiment, or a microwave crossover in a second embodiment, couple electromagnetic power from the feed system to the radiators through the shielding sheet. In the case of the coupling slots, the feed system provides phase quadrature signals for development of circularly polarized radiation. The crossover provides only a linearly polarized wave, and is formed of two coplanar waveguides, one in the shielding sheet and one in the bottom sheet.

Abstract: A modular direct radiating antenna system for producing highly contoured beam patterns is disclosed. The system comprises a plurality of array modules, each having a number of radiation elements. An intramodule feed network is provided to communicate RF energy between a module port and the radiation elements in an equal-power, equal-phase relationship. A second feed network, an intermodule feed network, is provided to communicate RF energy between an antenna system port and the respective module ports. The second feed network is adapted to couple the power and adjust the electrical path lengths so that the RF power communicate between the respective module ports and the system port is of predetermined relative amplitudes and phases. The intermodule excitation power and phase distribution across the entire planar array aperture produces the desired contoured beam to encompass a required area.

Abstract: An antenna system includes an array of microstrip antenna elements wherein each of the elements includes two or more radiators. Electromagnetic signals are coupled from an input terminal of each element via one or more circulators which allow for application of an input signal to a first of the radiators followed by rerouting of respective signals to the next radiator. The radiators are turned to radiate at successively higher portions of the electromagnetic spectrum. By virtue of reflections of higher frequency radiation from a radiator tuned to a lower portion of the signal spectrum, each radiator radiates only that portion of the signal spectrum falling within the bandwidth of the radiator. By using three radiators, each antenna element is capable of radiating a signal spectrum three times as wide as are the bandwidths of a single radiator. Included within the antenna system is one or more power dividers to form one or more beams of radiation.

Abstract: A credit card and charge slip are provided which resist credit card fraud. The credit card has auxiliary characters and corresponding dates at which each should be used, the auxiliary characters not being embossed at a copy area as are the numbers of the credit card. A merchant finalizes a credit card purchase by writing the auxiliary character only on the bank copy of the credit slip. The credit slip can be formed with aligned holes in all of the sheets except the bank sheet, so a merchant can write the auxiliary character directly on the bank sheet without even partially separating the sheet.

Abstract: A waveguide post slides through a resilient barrel which is adjustably clamped against the waveguide post to control its slidability and provide reliable electric contact. As a sliding short for a coaxial transmisson line termination, a shorting bar incorporating two resilient barrels engages both the inner and outer conductors of the coaxial transmission line with resilient clamping and reliable electrical conduction.