Patent Application
20170149114
This application relates to radio frequency waveguides and, more specifically, to a self-adjusting waveguide that compensates for out-of-flatness conditions in a circuit card assembly.
Waveguides are well-known circuit components that enable a signal to propagate with minimal loss of energy. The most common are conductive metal tubes that carry high frequency radio waves, such as microwaves. However, the miniaturization of electronic components presents unique problems in implementing waveguides on a very dense circuit card assembly (CCA). The high component density and high level of integration leave very little available board area to integrate traditional waveguides or patch launches, which results in the use of dielectrically loaded waveguides to reduce size.
In order to reduce size, a high dielectrically loaded waveguide may be used with several steps to transition to free space. Using a high dielectric allows the waveguide size to be miniaturized, but also makes the waveguide highly sensitive to physical gaps in the stack up due to the impedance transition from the CCA to the waveguide. Due to the high number of contact points and large surface area, the relative flatness (or lack of flatness) of the CCA becomes a cause for concern in assuring good waveguide-to-CCA contact across the entire surface.
Therefore, there is a need for improved methods of implementing a waveguide on a circuit card assembly (CCA).
To address the above-discussed deficiencies of the prior art, it is a primary object to provide an electronic circuit assembly comprising: i) a circuit card assembly having circuits integrated on a circuit surface thereof; ii) a housing having an upper surface and a lower surface, the lower surface disposed on the circuit surface of the circuit card assembly, the housing comprising a via extending from the lower surface to the upper surface; and iii) a waveguide assembly disposed in the via. The waveguide assembly comprises: a) a first waveguide having a first dielectric value, a contact end of the first waveguide configured to make contact with the circuit surface of the circuit card assembly; b) a second waveguide having a second dielectric value, wherein the first dielectric value is greater than the second dielectric value; and c) a carrier for holding the first waveguide in contact with the second waveguide. The electronic circuit assembly further comprises: iv) a wave washer disposed in the via on a support surface of the carrier; and v) a third waveguide having a third dielectric value, wherein the second dielectric value is greater than the third dielectric value, and wherein the third waveguide is disposed in the via between an end of the second waveguide and the upper surface of the housing.
In one embodiment, the carrier is metallic.
In another embodiment, the wave washer acts to press apart the third waveguide and the waveguide assembly such that the contact end of the first waveguide is pressed into contact with the circuit surface of the circuit card assembly.
In still another embodiment, a first surface of the carrier comprises a recess in which the second waveguide is positioned and wherein a portion of the carrier forms a hole that extends from the recess to a second surface of the carrier, wherein the first waveguide is inserted into the hole in order to make contact with the second waveguide positioned in the recess.
In yet another embodiment, the first waveguide and the second waveguide are bonded to the carrier.
Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.
For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:
The present disclosure is directed to a self-adjusting waveguide that is a dielectrically loaded multistep waveguide that incorporates a lower free sliding assembly and an upper fixed dielectric. A wave washer is placed between the fixed dielectric and the lower assembly to allow the lower assembly to adjust to variations in the contact height arising from out-of-flatness conditions in a circuit card assembly (CCA) in which the waveguide is implemented.
Waveguide assembly 105 comprises low dielectric loaded waveguide 120, middle dielectric loaded waveguide 130, and high dielectric loaded waveguide 140. By way of example, low dielectric loaded waveguide 120 may be made of plastic or polymer and middle dielectric loaded waveguide 130 and high dielectric loaded waveguide 140 may be made of ceramic. Waveguide assembly 105 provides impedance matching between free space and CCA 110 to avoid reflections of the propagated wave.
Using a high dielectric load waveguide with several steps in the transition to free space reduces size. However, although the waveguide size is miniaturized, the waveguide becomes highly sensitive to physical gaps in the dielectric stack due to the impedance transition from the CCA to the waveguide. The improved waveguide disclosed herein overcomes the problems in the prior art by creating a dielectric assembly that is free to slide in the housing. The high and middle dielectric pieces are bonded to a metallic carrier, which is cured under compression to minimize the thickness of the glue joint between the dielectrics.
In the prior art, the electrical boundary is defined by the housing. Since the passage though the housing needed to be enlarged to allow the free sliding motion of the dielectric assembly, there was an air gap and diameter change introduced by the waveguide. To overcome this, the high and middle dielectric pieces were metalized. This metal layer defines a consistent electrical boundary despite any motion or gaps between the housing and the dielectric assembly.
In
Thus, in the completed multistep waveguide assembly 200, metallic carrier 220 forms a collar around middle dielectric loaded waveguide 210 and high dielectric loaded waveguide 230. Upper surface 221 of metallic carrier 220 may then be used to support a wave washer as described below in
Once each one of dielectric assembly 200A, dielectric assembly 200B, and dielectric assembly 200C is bonded (as shown in
Housing 305 is placed on top of flat plane 310 during assembly and each dielectric assembly 200 and wave washer 320 are captivated by pressing in one of low dielectric loaded waveguide 330A, 330B, or 330C. The low dielectric loaded waveguides 330 are slightly larger than the vias 306, such that a tight friction grip holds the low dielectric loaded waveguides 330 rigidly in place in housing 305. This creates zero gap 350 and zero gap 351 on both ends of each dielectric assembly 200 in the fully depressed state. Excess portions of low dielectric loaded waveguide 330 (indicated by dotted line 360) above the upper surface of housing 305 are removed. Vias 306A, 306B, and 306C are sized so that gap 399 provides a built-in clearance at the bottom of metallic carrier 220 that prevents metallic carrier 220 from bottoming (resting) on the inner horizontal surface of via 306.
Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.
