This application claims priority to Taiwanese Application No. 104201223, filed on Jan. 26, 2015, the contents of which are hereby incorporated by reference.
The disclosure relates to a converter for radio frequency (RF) signals, and more particularly to a balun device for ultra high frequency (UHF) signals.
A balun is used to match between a single-ended (or unbalanced) signal and a pair of differential (or balanced) signals.
Typically, a conventional RF balun is in the form of a magnetic core wound with windings. Such RF balun has a wide working frequency band of up to a GHz-level. Referring to
Referring to
Therefore, an object of the disclosure is to provide a balun device for UHF signals that can overcome the aforesaid drawbacks of the prior art.
According to the disclosure, a balun device includes a dielectric base plate, two conductive connection pads, a printed conductive track and a conductive ground pattern.
The conductive connection pads are formed on the dielectric base plate and are connectable respectively with a pair of first signal lines for a pair of differential signals. One of the conductive connection pads is further connectable with a second signal line for a single-ended signal. The printed conductive track is formed on the dielectric base plate and interconnects electrically the conductive connection pads.
The conductive ground pattern is formed on the dielectric base plate, and is surrounded by and spaced apart from the printed conductive track and the conductive connection pads.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment with reference to the accompanying drawings, of which:
Before the disclosure is described in greater detail, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure.
Referring to
In this embodiment, the dielectric base plate 11 is in the form of a rectangular printed circuit board, and is made of, for example, Bakelite or fiberglass.
The conductive connection pads 12 are formed on a base surface 111, for example, a top surface, of the dielectric base plate 11. The conductive connection pads 12 are connectable respectively with a pair of first signal lines (not shown) for the differential signals. One of the conductive connection pads 12 is further connectable with a second signal line (not shown) for the single-end signal. In this embodiment, the conductive connection pads 12 are symmetrical to each other about a central line (L) of the dielectric base plate 11 in a lengthwise direction (A) of the dielectric base plate 11.
The printed conductive track 13 is formed on the base surface 111 and interconnects electrically the conductive connection pads 12. The printed conductive track 13 has a width that may range from 0.5 mm to 2 mm. In this embodiment, the printed conductive track 13 is arranged so as to form, for example, two serpentine paths that are connected to each other and that are symmetrical to each other about the central line (L).
The conductive ground pattern 14 is formed on the base surface 111 of the dielectric base plate 11, and is surrounded by and spaced apart from the printed conductive track 13 and the conductive connection pads 12. The conductive ground pattern 14 includes a main pattern portion 141, and a plurality of extension pattern portions 142 that extend outwardly from the main pattern portion 141.
In this embodiment, the main pattern portion 141 is rectangular. The size of the main pattern portion 141 may be configured in a manner that a ratio of its length (i.e., the size in the lengthwise direction (A)) to its width (i.e., the size in a widthwise direction (B) of the dielectric base plate 11) ranges from 1 to 1.6 and that its area is less than 500 mm2.
The extension pattern portions 142 are divided into two groups. The groups of the extension pattern portions 142 are disposed, in a symmetrical manner, respectively on sides of the main pattern portion 141 that are opposite to each other in the lengthwise direction (A). The number of the extension pattern portions 142 of each group is not greater than five. The extension pattern portions 142 extend in the lengthwise direction (A) and have substantially similar lengths. In this embodiment, the extension pattern portions 142 are bar-shaped and have the same length and width. The extension pattern portions 142 of each group are approximately equidistantly spaced. It is noted that a ratio of the length of the extension pattern portions 142 to the width of the same is less than 100. In addition, the length of the extension pattern portions 142 ranges from 5 mm to 30 mm, and the width of the extension pattern portions 142 ranges from 0.5 mm to 3 mm.
Further, due to the configuration of the conductive ground pattern 14, the printed conductive track 13 is arranged along an outer contour of the conductive ground pattern 14, and is spaced apart from the conductive ground pattern 14 by a predetermined spacing. In this embodiment, the predetermined spacing ranges from 0.3 mm to 2 mm.
For well performance of the balun device, as shown in
Referring to
The following are some of the advantages attributed to the balun device of this disclosure:
1. The conductive connection pads 12, the printed conductive track 13 and the conductive ground pattern 14 are directly formed on the dielectric base plate 11. Therefore, the balun device of this disclosure has a relatively low fabrication cost.
2. The impedance ratio of the balun device of this disclosure can be easily designed by adjusting number and length of the extension pattern portions 142 of the conductive ground pattern 14 to satisfy a desired application.
3. From the curve 93 of
While the disclosure has been described in connection with what is considered the exemplary embodiment, it is understood that this disclosure is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Number | Date | Country | Kind |
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104201223 U | Jan 2015 | TW | national |
Number | Name | Date | Kind |
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5061910 | Bouny | Oct 1991 | A |
7302249 | Fudem | Nov 2007 | B1 |
20140022027 | Cammarata | Jan 2014 | A1 |
Number | Date | Country | |
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20160218409 A1 | Jul 2016 | US |