Phase matched couple-resonator 2.4 GHz WiFi antenna for laptop computers and mobile devices

Abstract

A lightweight 2.4 GHZ antenna designed to be clipped onto a laptop computer or mobile device to extend the range of operation. The device consists of a tubular plastic frame upon which wire loops and a reflector are mounted and aimed toward the intended source of Wi-Fi signal. Radio-Frequency energy is transferred bidirectionally from the antenna to embedded antennas in the laptop computer or mobile device so no hardwired connection is necessary. Operation requires no power. The device can be scaled to 5 GHz Wi-Fi and other frequency bands including cellular.

Claims

1. An apparatus for extending the range of 2.4 GHz Wi-Fi signals comprising: a resonant loop shaped to the aperture of embedded antennas in a laptop computer or mobile device that provides near-field critical coupling of radio frequency energy when clipped on the bezel of the display of the laptop computer or mobile device; an antenna that introduces no delay into the reception and transmission of Wi-Fi signals to the embedded antennas of the laptop computer or mobile device for the purpose of retaining stable additive properties of gain; and an integral hollow body structure for accurate visual sighting to a Wi-Fi hotspot.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) Three views are shown on one page.

(2) FIG. 1 is a side view that shows the square PVC tube PVC1 and the spacing of the antenna loops LI, L2, and L3.

(3) FIG. 2 is a front view that shows the relative size and shaping of the antenna loops LI, L2, and L3, and the taper of the pliant material PM1.

(4) FIG. 3 is a top view that shows another dimension of the reflector PCB1 and the pliant material PM1.

(5) PVC1 is a square tube of PVC forming the body of the antenna. The walls are 1/16 inch thick. The dimensions are: length 4.75 inches, width 0.75 inches.

(6) PM1 is a block of pliant material for holding the antenna to a laptop display bezel. Length 1 inch, width 1 inch, depth inch.

(7) PCB1 is a reflector made from copper-clad PCB. Width 2.5 inch, height 1.25 inch, thickness 0.062 inch.

(8) LI is the antenna driven element and pick-up loop 1. Width 1.7 inch, height 0.35 inch tapering to 0.55 inch in the middle.

(9) L2 is the antenna first director loop 2. Width 1.45 inch, height 0.93 inch.

(10) L2 is the antenna second director loop 3. Width 1.1 inch, height 1.1 inch.

DETAILED DESCRIPTION OF THE INVENTION

(11) The phase matched coupled-resonator antenna increases the gain of Wi-Fi signals by shaping the incoming and outgoing beams of Wi-Fi RF energy in the forward direction. As shown in FIG. 1 of the Drawing, the RF energy passes through two loop directors L3 and L2 and a driven loop element LI that progressively shape the RF into a rectangular form similar to that of the embedded antennas in the laptop computer or mobile device. The relative shapes of the antenna elements are shown best in FIG. 2, as the outermost loop L3 is closest to being circular so the gain is highest, and the innermost loop LI is shaped to interface efficiently with embedded antennas of the inverted-f or dipole style. The middle loop L2 is shaped to be dimensionally intermediate between LI and L3 and resonant at 2.45 GHz to facilitate the transfer of RF energy. The antenna elements are designed using Yagi antenna theory specially adapted for loop elements rather than dipoles, and modeled using the Numerical Electromagnetics Code.

(12) The RF is coupled bidirectionally across the plastic bezel between the driven antenna element and the embedded antenna of the computing device. These elements share two fundamental properties, that of resonance centered on 2.45 GHz, and a rectangular shape of approximately 0.4 in.1.70 in., as seen in the front view of LI in FIG. 2. With these parameters matched, and the gap between the elements of one tenth of an inch at this frequency band, the two antennas tend to resonate in tandem.

(13) The 2 wavelength spatial diversity, with a wavelength at 2.45 GHz being 4.81 inches, allows for approximately 10 inches spacing between the two embedded antennas in a laptop. For a display that is 12 inches wide, the embedded antennas can usually be found 1 inch in from the upper corners of the display bezel. In mobile devices a closer spacing of 0.5 wavelength is typically used. Regardless of the exact method of mobile device construction, the location of the embedded antennas can be found by experimentation or by referring to product literature.

(14) A block of closed-cell plastic foam material PM1 that is transparent to RF creates a slot to hold the antenna in place so the driven element is laying flat against the top of the laptop display. Closed-cell ethylene-vinyl acetate (EVA) or polyethylene foam are suitable materials for this part.

(15) In practice the invention works best when the target Wi-Fi hotspot is in a line of sight from your location, although it is not required. Locate the laptop or mobile device so it can be directed toward the target with a minimum of foliage and obstructions. Slip the Wi-Fi antenna over the bezel of your computing device where the embedded antenna is located on whichever side is most convenient. To cover long distances, sight through the hollow antenna body PVC1 to frame the target in view. If the target was initially beyond the capture range, it should be detected by the Wi-Fi tuner momentarily. If it was already detected but too weak to use, the tuner may take a minute to resolve the change in amplitude before updating. With the Wi-Fi antenna in place, the range of a Wi-Fi connection can increase by a factor of three under good conditions.

(16) The beam of the invention is perpendicular to the plane of the laptop display, so depending on which way the antenna is placed, the strongest Wi-Fi energy can be received from forward or rearward. The antenna frame PVC1 is composed of 0.75 inch square PVC tubing, but could also be constructed of injection-molded plastic to reinforce the mounting of the driven element on the underside. Square PVC tubing is preferred over round tubing due to the relative ease of drilling and cutting it accurately. At the back of the antenna the reflector PCB1 doubles the RF power in the forward direction, but may block weak signals coining from the rear.

(17) To construct the Wi-Fi phase matched coupled resonator antenna prototype, the antenna components, reflector PCB1, pliant material PM1, driven element LI and directors L2, L3 are mounted to the square PVC tube PVC1 as shown in the three Figures, side view, front view, and top view in the Drawing. First cut the tubing to a length of 4.75 inches to make PVC1. To mount the reflector PCB1, come back a quarter inch from one end and cut a inch long slot from one side to the other, perpendicular to the wall of the square tube. A standard hacksaw blade has the proper width to cut a slot for a standard thickness PCB, 0.062 inch. All the slots will be on the same side of the PVC tube PVC1. Cut a single or double-sided copper clad PCB to 2.5 by 1.25 inches to make PCB1. Test fit PCB1 in the slot and later it will be glued in place with cyanoacrylate after installing the pliant material PM1 around PVC1.

(18) Move forward on PVC1 1.2 inches from the first slot, and saw the next slot for the driven element LI in a similar manner, to a width of 0.08 inches for #12 copper wire, and a depth of 0.1 inch so the wire when mounted will be flush with the surface of PVC1. Use two hacksaw blades mounted together side by side to get the proper width. Make LI out of 4.14 inches of copper wire. Shape it with needle nose pliers so it measures 1.7 inches wide on the top section, 0.35 inches downward on both ends, and 0.87 inches bent together and soldered to be 0.55 inches tall in the middle, forming a modified rectangle as in LI of FIG. 2. Shape the corners as sharply as possible but not so sharply that it stresses the copper.

(19) Then move forward another 1.15 inches and saw another slot for the first director L2 to the same width, 0.08 inch, and a depth of a quarter inch. L2 is made from 4.76 inches of #12 copper wire. Shape the wire so its 1.45 inches on the top section, 0.93 inches downward on both ends, and 0.725 inches soldered together in the middle of the bottom side to form a complete rectangle.

(20) Next, move forward to a point 2.9 inches from the LI slot. It should be a quarter inch from the front edge of the tube PVC1. Saw another slot for the second director L3, also 0.08 inch wide and a quarter inch deep. Make L3 from 4.4 inches of #12 copper wire. Shape a square loop that's 1.1 inches on each side. Solder the ends together in the middle of the bottom side to form a symmetrical square.

(21) Lastly, slip the plastic foam pliant material PM1 around the PVC tubing behind the driven element LI. Install the reflector PCB1 in the open slot behind LI, center in position and tack in place with four points of cyanoacrylate against PVC1. Lay the Wi-Fi antenna upside-down in a flat area on a piece of cardboard, and install the loops LI, L2 and L3. Tack the loops sparingly with cyanoacrylate perpendicular to the body of PVC1 in their respective slots. Center the loops before the glue dries. Allow to dry completely before handling.

(22) Slide the plastic foam material rearward against the reflector and tack it in place with cyanoacrylate. A slot of a quarter inch width should be formed behind the driven antenna element to accommodate the laptop computer or mobile device. The Wi-Fi antenna could also be constructed by injection molding plastic to the required specifications to avoid the labor-intensive costs of assembly. Construction of the Wi-Fi phase-matched coupled resonator antenna is complete.