Build Your Own Long-range WiFi Antenna for Less than $100

Posted by Darrell Nicholson at 11:13AM - Comments: (10)

Holes drilled in the top and plugged with foam ear plugs
make disassembly easier.

As most sailors have found, trying to use a typical laptop WiFi card to connect to a marina or yacht club hotspot doesn’t cut it. A more acceptable compromise is an amplified WiFi card which can theoretically boost transmission power to about 1,000 milliwatts.

PVC plumbing protects the USB amplifier from the elements.

Practical Sailor has reviewed several solutions for boosting your WiFi connectivity on board, including the 5MileWiFi (January 2009), the Bitstorm, Wave WiFi, and The Wirie (April 2010). Reader Ed Mini of Mystic, Conn., recently wrote us about his DIY approach to ending his frustrations with lackluster Internet connections while aboard Margalo, his Columbia 8.7 (bought new in 1977). His setup includes some of the same components as systems we’ve tested, but his is more affordable than the off-the-shelf systems that PS has tested, and is easy to set up. Although PS has not yet tested this particular device, we have used some of the components. Mini said it has given him flawless performance for two seasons.

Mini’s setup uses the same amplifier as The Wirie but it costs less than $100, compared to The Wirie’s $250 pricetag. The installation takes about an hour and requires no electrical know-how. Instead of using a watertight box as The Wirie does, Mini uses PVC fittings from Home Depot, which he claims are completely watertight. Except for the PVC, he bought all of his materials online at Data Alliance. Data Alliance also sells the Ubiquiti Bullet2 wireless access point ($40) used in the two other WiFi systems we reviewed in the January 2009 article on marine WiFi systems.


Amplified WiFi Card: The card is an Alfa AWUS036H ($27.50); Mini’s is rated at 500 milliwatts, but the latest version is rated by the manufacturer at 1,000 milliwatts.

Antenna: The antenna is a 2.4 gHz, 24-inch, 8.5-decibel vertical antenna ($18) with an N-type female connector at the bottom. Although Mini did not buy the “marine” antenna listed on the Data Alliance website, the marine version is only a few dollars more.

Software: You will need to install the driver and interface for the chipset in the new Alfa card. This card’s chipset is a Realtek 8187L; the proper PC or Mac driver and the interface utility can be found on the Realtek website, if it’s not included with the card. [Owners of newer Macs should check Alfa website for software, see comment below.]

Housing: The PVC container assembly comprises a 3-inch diameter pipe that is 6 inches long, with a matching domed cap and a screw-on base. (About $10 total for the parts.)

Accessories: Mini used a 10-inch-long coaxial pigtail (RP-SMA male to N male) to connect the card to the antenna. To connect the Alfa Wi-Fi booster to his computer, he used a 2-foot-long USB male mini-B to male mini-A adapter cable to start the cable run. After that, he used an an active repeater USB cable to connect to the computer. The active USB cable contains a small booster that is needed to overcome any signal loss over the length of the wire run. The cable is only 12 feet long, but multiple active USB cables can be “daisy-chained” together for longer runs. Although most instructions for this sort of installation call for a coaxial cable, using it would quickly negate any signal gain from your new amplified antenna.

The PVC base cap screws on.


1. Install the driver and utility to the computer. (If you need help with this, find the nearest teenager and ask for help).

2. Using the USB cables, coaxial pigtail and required adapter, assemble the antenna components for testing. The sequence of components, working from your computer to the 8.5 dB antenna is as follows: computer, active USB cable (2 or more if needed), USB male mini-B to USB male mini-A adapter cable, Alfa WiFi adapter, pigtail adapter, 8.5 dB antenna. Be sure the booster in the active USB cable (a conspicuous bulge) is at the end farthest from the computer. When testing, remember that you will NOT be using the internal WiFi software; you will be using the Realtek utility that comes with the card. Click on its icon; the Realtek management screen will appear.

3. To build the PVC housing, first drill a hole in the domed PVC cap to take the base of the antenna. The base of the antenna is too short to leave enough threads for screwing on the retaining ring, but Mini was able to secure his by snugging up the coaxial pigtail to hold it all together.

4. Cut a hole in the screw-on base-cap to let the USB cable exit the bottom. This hole should not be in the center of the base-cap, as it might interfere with any threaded center-mounting arrangement.

5. To secure the card inside the PVC pipe, cut a 2-inch-long piece of scrap wood so that it fits snugly inside the pipe, then glue it in place. Mini glued the card to the wood insert, but one could easily use adhesive Velcro tape, which would allow you to more easily remove the WiFi adapter, if needed.

6. Cut a hole in the base to hold a mounting clamp if you intend to mount the antenna on deck. (Mini modified a standard antenna rail clamp.)

The homemade antenna uses the same Alfa WiFi amplifier as
The Wirie.

7. Drill a couple of quarter-inch holes in the cap to make it easy to disassemble using a long screwdriver for leverage. Fill the holes with earplugs to keep water out.

8. Put everything together. The antenna will stick out the top, the USB cable will come out of the bottom, and the antenna mounting clamp will be on the bottom-center—and all will be waterproof.

9. If you want to be able to hang the antenna in the rigging for greater range in some places, you can screw on a small ring-eye.

Comments (9)

Dove, i totally hear what you are saying. However I ran into a situation where connectivity was vital. Granted this was not wi-fi but wireless. In my case I has an engine failure. I had done extensive troubleshooting on the fuel supply system which I suspected to be the problem however I eventually ran out of ideas. At that point I glanced over and saw my iphone which had a signal. I thought why don't I google my problem and see if anyone had run into it in the past. Sure enough, three of four years ago some sailor with a 2GM20 had had the same problem and threw out a strategy I had not tried. Back to he engine I went and within 15 minutes I was running. It is this type of connectivity that is so helpful.

Having said all of the above I am astonished at the current state of affairs, you can't go to a restaurant anymore without a TV in your face and your fellow diners buried in their smartphones. I am pretty hard over about not doing any of that when I am sailing.

Posted by: Mike Cunningham | August 17, 2013 11:17 AM    Report this comment

Thanks but no thanks, I sail because I love the wind, waves, and my boat. To me sailing is therapy. In fact,I would much rather have a conversation with a dolfin than permit a useless twitter or facebook junkie aboard. Those who sail with me, sail to enjoy the peace plus experience time absent of an electronic screen advising latest world events. While I enjoy the importance of electronic communication and navigation, adding more electronic clutter makes little sense.

Posted by: Dove | November 23, 2012 8:12 AM    Report this comment

Increasing your transmit power does little to improve the connection since the received signal is not increased. On the contrary, with the proliferation of WIFI access points in many harbours (and there are only 3 channels that do not overlap), if everybody increases their power the narrow WIFI band just gets jammed. It would be better to use a directional antenna, as it increases both your transmitted and received signals, while reducing congestion (you are mostly radiating towards the access point, not towards the whole harbour). In fact using an directional antenna has allowed us to connect in many difficult situations, by eliminating the interference from strong unwanted signals. Of course the disadvantage is that if you swing at anchor you sometimes have to re-orient the antenna. The Ubiquity Nanostation2 (about $85) has the directional antenna built in, so installation is very easy. No need for coax cables. It connects with a network cable (also for the power, which can be AC or 12VDC), so you have to use your computer's wired network connection (as opposed to USB). Advantages: no driver required, compatible with all OS (Mac or PC), no limit to cable length, easy to share with several computers via a network switch. Disadvantages: harder to set-up the first time. Although not a marine unit it is a professional outdoor device, with no metal to corrode. The Ubiquity products are marketed to professionals, so the first time configuration is relatively complicated. By the way, it also has a connection for an external antenna (e.g. omni) if you feel the need for it. We did at first, but soon realized that the built-in directional was much better.

Posted by: LeoL | June 16, 2011 7:13 PM    Report this comment

Heads up fellow Mac users, Realtek apparently is not supporting Mac OS 10.6. After installing the software and the install failing I contacted Realtek asking for suggestions. I included a screen shot of the error message which said "System Extension cannot be used" and my OS version, they replied with: "sorry that 8187L don't have plan to support Mac 10.6"

Posted by: Aistear | May 25, 2011 10:31 PM    Report this comment

The text has been fixed to reflect the correct pigtail connector between the card and the antenna. It is a Male to Male. The part number at Data-alliance is P4, as David pointed out. Thanks again for the feedback, and I'm sorry about the mixup.

Posted by: DARRELL N | April 15, 2011 7:38 AM    Report this comment

Thanks David on the pigtail details. Author had confirmed another part #, sorry about the inconvenience.

Posted by: DARRELL N | April 11, 2011 5:17 AM    Report this comment

WARNING!!! In the article it states, "Accessories: Mini used a 6-inch-long coaxial pigtail RP-SMA female (at the Alpha end) to N female (8.5 dB antenna end) to connect the card to the antenna." The is exactly the OPPOSITE of what is needed. I will now have to return these parts and get the Male to Male adapter. For reference the part is listed as: Antenna cable: RP-SMA male to N male: 10-inch. For wireless / WiFi network. Part#: P4, SKU: P4

Posted by: David C | April 7, 2011 6:44 PM    Report this comment

Hi Patty. I'll see if we can get those photos brought in.

Posted by: DARRELL N | March 20, 2011 9:41 PM    Report this comment

It looks like there are pictures on the page of the setup but I see nothing there but the captions.

Posted by: PATTY H | March 19, 2011 3:17 AM    Report this comment

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