Abstract: A switched beam forming network is disclosed having an antenna array and an integral beam forming network configured to selectively provide directional and omnidirectional antenna radiation patterns. Four 90-degree hybrids are serially interconnected to form a 4×4 hybrid matrix. The hybrid matrix receives and transmits signals through antenna monopoles and is configured to selectively switch between directional and omnidirectional operation. At least four antenna terminals connect the hybrid matrix to the antenna monopoles. Four input/output ports connect the hybrid matrix to a transmit/receive network through connecting lines. A plurality of switches are selectively actuatable to form the beam forming network.

Abstract: The present invention is a combined aircraft TCAS/Transponder with common antenna system and transmitter. Common TCAS/Transponder multi-monopole top and bottom antennas may be connected to a top and bottom antenna modules, the top and bottom antenna modules being electrically coupled to the combined TCAS/Transponder transmitter/receiver block through connection lines.

Abstract: A directional/omnidirectional antenna system is disclosed. A first printed circuit board has capacitive hats disposed thereon. Each capacitive hat is in association with one of an array of folded monopoles. A second printed circuit board has a switched beam forming network formed thereon. The switched beam forming network is configured to provide a predetermined omnidirectional antenna operation at a first switching position, and a predetermined directional antenna operation at a second switching position. Each of a plurality of feeding elements is associated with one of the folded monopoles. Each feeding element is coupled to one of the capacitive hats and to an antenna terminal. Shorting elements of the folded monopoles are coupled to the capacitive hats and to a ground plate of the antenna. A plurality of decoupling elements improve the antenna pattern for directional and omnidirectional modes and provide greater antenna gain.

Abstract: A step attenuator for use in attenuating an electromagnetic signal. The step attenuator includes a first path having a plurality of attenuator structures provided therein, each attenuator structure being selectively actuated to permit the signal to pass therethrough. A second path is disposed in parallel with the first path, the second path permitting the signal to selectively bypass the first path. A third path is disposed in series with the first and second paths and includes at least one attenuator structure that is selectively actuated to permit the signal to pass therethrough.

Abstract: A single antenna FM radio altimeter operates in continuous wave (CW) and interrupted continuous wave (ICW) modes to provide an altitude indication. An altimeter transmitter generates a constant FM period CW signal below a critical altitude and a variable FM period ICW signal above the critical altitude. The single antenna, connected to the transmitter and receiver, radiates and receives the CW and the ICW signals. The receiver provides a beat frequency signal. A processor compares the beat frequency signal and the variable FM period signal to critical altitude reference signals and switches the altimeter between the modes accordingly. The processing function provides the transmitter a constant period modulation signal below the critical altitude and a variable FM period signal above the critical altitude. The processing function provides the altitude indication from the beat frequency signal below the critical altitude and from the variable FM period signal above the critical altitude.

Abstract: Disclosed are microstrip resonators and bandpass filters using the same. The bandpass filters of the present invention include an input, an output and multiple resonators coupled between the input and the output. A first resonator coupled in series between the input and the output includes a first line conductor having first and second ends and a second line conductor having first and second ends. The first and second line conductors are positioned relative to one another such that the second end of the first line conductor is connected to the second end of the second line conductor, forming a first angle of the first resonator between the first and second line conductors. The first angle of the first resonator is substantially less than 180 degrees so that a physical length of the resonator, taken in a direction from the input to the output, is less than an electrical length of the first resonator.