Single port delay element

#Aspects of the present invention are directed generally to a system and method for delaying transmission signals, more particularly, aspects of the invention relate to a system and method of generating delay using one or more singly terminated band-pass filters.

#Delay lines ideally have a uniform, fixed amount of insertion delay and constant phase over a predetermined frequency range. These ideal objectives are difficult to achieve in high power applications and when generating long delays, e.g., delays in excess of a few nanoseconds, more particularly delays in excess of 15 nanoseconds, and preferably delays greater than 30 nanoseconds, even more preferably delays in excess of 50 ns.

#One application in which the generation of long delays is desirable involves the testing of devices communicating over a wireless local area network, or “WLAN.” Such devices may include laptops, desktops, printers, cellular phones and similar devices. Incorporated in such devices are WLAN cards, which enable the devices to perform wireless communication.

#The foregoing summary and description of the preferred embodiments of the invention is intended to facilitate a better understanding of the invention, but is not intended to limit the scope of the invention.

#The following represents brief descriptions of the drawings, wherein:

#FIG. 1 shows an exemplary embodiment of the present invention.

#In the following detailed description of the invention, it should be noted that, when appropriate, like reference numerals and characters may be used to designate identical, corresponding or similar components in differing figure drawings. Further, in the detailed description to follow, exemplary embodiments and values may be described, however, the present invention is not intended to be limited thereto.

#FIG. 1 shows an illustrative embodiment of the present invention. In particular, according to this example of the present invention, the system includes a circulator 10 coupled to a singly terminated delay element, filter 30, through port 20. Circulator 10 may be one of any of a number of such devices known in the art. Circulator 10 may include multiple ports or terminals, such as ports 40, 50, and the port coupled to port 20, and the device may be constructed such that that signals entering one port are transmitted in a desired direction to an adjacent port for output. The ports, including port 20, may be comprised of one or more terminals or connections, or may be comprised of an opening in a unitary chassis design surrounding the filter, the circulator, or both.

#FIG. 1A shows, in relevant part, a cross-section of filter 30 of the embodiment of the invention illustrated in FIG. 1. In particular, the figure shows one possible internal construction of the filter, in this case including a linear array of resonators 3. Filter 30 may be a band-pass filter and may include a plurality of resonators as shown in FIG. 1A, but may be one of any number of filters and/or devices that may be configured to operate in a manner similar to that provided below. In a preferred embodiment, because a minimal amount of loss may be acceptable, metal resonators may be utilized thereby avoiding the cost associated with ceramic resonators. Moreover, the inventor has discovered that use of metal resonators is preferred over the use of ceramic resonators because the metal resonators exhibited more favorable cost and performance characteristics. Nevertheless, the use of ceramic resonators is within the scope of aspects of this invention.