Wireless/GPS Antennas & Antenna Wire

Hello all,
As some of you might know from my 'handle' here on the forum, I am a HAM radio operator - Extra Class. This gives me some unique perspectives when it comes to electronics and antennas. This is true for WWAN, WiFi, GPS, and Bluetooth. I have a lot of experience with creating and modifying antennas from 1.8MHz to above 300GHz, BUT, I have an antenna modeling program and handheld analyzer to make sure I won't blow anything up.

I just read, in another post, a gentleman that was thinking of hooking up his laptop's WiFi card to a modified sat dish. While this is something that HAMs have been doing for years now, both with routers and computer cards-internal and external (I get about 3 miles from my home router as it has an small amplifier and focused signal - with no mod to my laptops), this is something that can cause a LOT of damage to a WiFi card from many different, easily made mistakes or miscalculations. First and foremost, some (maybe most???) factory cards are WAY underpowered for such a set-up and can blow the final stage in the built-in amplifier on the card - ESPECIALLY of you mis-match impedance on the coax cable (50ohm, 75ohm, 100ohm, etc). If you are careful, utilize low-loss cables & connectors, match the impedance (Usually 50ohm), use only the length of line needed, and use a commercial antenna, you should be OK, but be warned, I have replaced many cards on laptops for people who wanted to 'make a better WiFi antenna'.

Each year for the local fair, I set-up and configure the WiFi and Internet access for the entire fair grounds. I use several directional and non-directional antennas for the location. All of these hook up to simple WRT54G Linksys routers, utilizing the DD-WRT firmware, with sma-to-N style connectors, low loss ( LMR-400 cable), and strategically placed WiFi antennas ( four 28dbi Yagi, eight 20dbi Panel, and four 15dbi Omni-Directional). All of these access points are wirelessly linked using DD-WRT's Bridge abilities, and provides a HUGE area with 5 solid bars of service. This gives everyone whom is allowed, internet access (We use WPA2 for wireless security, as well as encryption on sensitive computers. (In the next two years we will make a full upgrade to b/g/n routers ( Linksys/Cisco WRT160NL) utilizing the same antenna system. I estimate that this will quadruple throughput for the individual user; mostly due to the increased bandwidth for the bridging of the routers.

The only other point I wanted to bring up is to take a look at some of the 'HAM Radio' stores and supply outlets. While some of you have been doing these modifications for years, HAMs have been doing it for decades. HAM operators have differing bands that they are allowed to use based on FCC licensing, but basically we are currently allowed to use frequencies from ULF (currently running ULF experiments) to Microwaves and work these bands from earth and into space and back (Sat communication, meteor scatter communication, and EME Communication (Earth-Moon-Earth, bouncing signals off of the moon and back to earth) just to name some).

If you are interested in turning a sat dish into a WiFI antenna, I suggest getting a look at: http://www.engadget.com/2005/11/15/how-to-build-a-wifi-biquad-dish-antenna/ . They were able to get WiFi to go over 10 miles with thier set-up!!!! That page also has a great set-by-step on turning a dish into a well engineered directional WiFi dish (With a decent front to back ratio to boot!)

There is some great information on building and using your own antenna(s) here: http://www.dxzone.com/catalog/Antennas/WiFi/ . An important thing to remember is that we can cook food with radio waves, so don't become dinner by accident!! If anyone would like any help/advice, PLEASE don't hesitate to contact me by PM or on this thread. I would love the opportunity to give back to this forum in anyway possible. :wink:

Have fun & be safe!!

Beau
K1SFD
**Wonders what kind of cover I should put on the books I keep writing for posts...hmmmm hard cover or paperback....I wanna be a 'paperback writer'....'paperback writer' (Name that music group)

 

You know what,

that actually was a great post. It's amazing what you can accomplish by looking at things from another perspective.

And, thanks for offering to help. Compared to the number of humans who naturally can think of 18 ways something wont' work, but not one that will, it's refreshing to see someone who isn't a dreamkiller...

-Shawn

 

Awww, ma-a-an-n-n... yew mean ahh cain't plug muh layptahp inter muh 10m linear and gazillion-tuple the reach? All ahh need izz a little bit of beer can and sum NASCAR Tape... it'll be FINE...

mnem
Speakin' uh which... time to empty a few beer cans for "raw material"...

 

mnem, You kill me!! :laugh:
The scary part is the number of people who have tried such things!!! :laugh: The really funny part is how they try to explain it to you, thinking that if they explain it right, you'll be able to get it covered under a warranty!!

Beau

 

Dewed, you need to talk with Marconi... he's an old-timer, serious HAM.

You see his sig? That's him tracking Apollo 13 with homebrew gear. I was too as a little kid, I spent a lot of time in Skipland down on the 80m & 160m bands skeeting on my grand-dad's ticket. When he died I kindof drifted away from it, tho I do wish I still had my old FT-101EX...

mnem
- - . - / . - . / . - . . / . . - - . .

 

This is what I was thinking about during your warning. It can be done if you mod it to work. Of course everything can work with a mod!

Both my parents were Hams... My Dad was K4JDG as well as W4GFB and my Mom was WA4MCD. That is where I got my "McGyver" gene I guess. I started at a young age under the hood with my Dad.


<This is Hawaii, circa 1964>

I used to go out an help him set up for Field Day every year... That was a blast. I used to go to all the Hamfests with him and also either hid or hunted with him during the "Rabbit Hunts".... There were a lot of fun times. I really miss the drone of the ham shack in the back ground. If I had a penny for every time I heard CQ, CQ, CQ....

Ahhh... Memories....

 

Ya, Field Day is one of my favorite days of the year.:GEEK: I got interested in Communicatios when I was young, around 8 or so... My father was an electrical engineer, and encouraged me to experiment with anything and everything.. You know how most kids like to take everything apart, well I was one of the few who liked to put it back together and make sure it still worked.... Or make it better Anyway, I was also into computers from that age and sold one of my first programs to Activision when I was 10... They intergrated it into a few of thier second generation games for the C64... and then the C128.. I wish it paid as good then as it does now!! My first computer was a TRS80 CoCo... I LOVED that thing... Anyway, It always amazed me that you can talk to someone on the other side of the world, so I was drawn in. I used to fabricate and make a lot of my own 'homebrew' gear(within the leagal bounds of the FCC ), but for one reason or another never got around to getting my FCC license until after I became a Comm Officer. By that thime I was an expert in Public Service radio systems for Police/Fire/EMS and knew waaay too much about voice and data communication. I just loved everything about it and soaked up all of the knowledge that I could (Four Associate Degrees!). When I moved to Stratham in the mid-90s, the FD and EOC noticed my skills and immeditaely handed everything to me *read dropped in my lap* it wasn't a terrible mess, but needed some help... Not to brag, but since then Communications has had ZERO deficencies on our state oversight drills. Needless to say, I take a lot of pride in my *work*, even though it's volunteer.

So... Having the chance to blend my computer skills and communications skills is serendipity for me! I have the *my* toughbooks to thank for that, as well as all of the contributing members of this forum who have been brave enough to pave the way for the rest! Too all of you who contribute, Thank you -seriously- for your ingenutiy, and in some cases bravery, in pushing the envelope!

So, TB... when are you going to HAM up??? No Code requirement anymore!!! Just the individual elements for the license class (Tech, Genreal, and Extra). I was one of the final Code Takers! BTW, If you get your license, there is a provision to take over one of your parent's call signs, whether they are Silent Key or have just gave up thier license... I have some Audio files for the classes if you are interested... Just PM me and let me know! They are a little big, so if they can't fit in your inbox, or an FTP site, I would be willing to mail you the discs. I can't remember the size off the top of my head, they are on my Development desktop: (sorry, I have to brag here!!!!)
Samsung T260HD 26" Widescreen LCD Monitor - 1080p, 1920x1200, WUXGA, 1000:1, 5ms, HDMI
Intel Core i7 920 Quad Core 2.66Ghz
8Gb DDR3-1066
250GB SATAII Primary Drive, 2x500GB SATAII Data & Storage Drives
NVIDA G210 Video Card 512MB DDR2 VRAM (DVI & HDMI), PCI Express x1 TV Tuner
Blu-ray Player & DVD±RW/RAM Dual Layer Lightscribe
Ultra X3 1000W Power Supply
Windows Vista Ultimate 64-Bit - Free Upgrade to WIN 7 Ultimate 64-Bit
Plus a 3TB NAS I just got and have to get up and running to relieve some congestion on the PC

I built it up myself off of a base Gateway PC ( Gateway FX6800-01E)
With my reseller discounts, I got one *&$#(* of a deal!!!


For TB's Posterity.... CQ... CQ... CQ... This is K1SFD, Kilo One Sierra Fox Delta... Calling CQ Dx.....


Beau

 

I wasn't sure whether to add this post to this thread or start a new one. Since it basically adds to the topic, I felt that this was the best sopt for it. SO...I wanted to add a little more about antennas, specifically Ground Planes.

As many of you have read, the ground plane added to an antenna can make a significant difference in the abilities of the antenna, especially with the active antennas that we use for GPS. But why, you ask??

Like with most things, for every action there is an equal an oposite reaction. Antennas function the best in a Dipole configuration. While this is significantly more difficult for HAM operators on the 160M Band (1.8 - 2.0 Mhz) where the anntenna would have to be 250 feet, split into 125 foot sections, in the 2.4Ghz band a dipole is 2 11/32 inches, or 1 3/16 inches per side.

The ground plane that is added to the antennas compensates or completes the missing half of the dipole. Taken from Wikipedia: A ground plane may consist of a natural surface, such as the Earth (or ocean) (or salt marsh) or an artificial surface of opportunity (such as the roof of a motor vehicle). A ground plane can also be a specially designed artificial surface (such as the radial elements of a quarter-wave ground plane antenna). Artificial (or substitute) grounds (e.g., ground planes) concerns the grounding structure for the antenna and includes the conductive structure used in place of the earth and which grounding structure is distinct from the earth.

By us adding that little strip of copper tape under the GPS antenna, we are creating an effective ground plane that is replacing that missing 1/2 of the dipole. While this works for ALL antennas, we see the biggest benifit in transmitting, followed closely by the active antennas we use for GPS. For the most effect, the distance that the copper tape extends from the center of the GPS should equal out to a specific wavelength (1/4, 1/2, full). While this isn't as important for 2.4Ghz as it is for 1.8Mhz, it will still add a degree of stable result that can easily be recreated.

If you are interested in learning more about antennas, here is a good introduction.

There is also an excellent set of antenna (and other) tutorials here at the electronics-tutorials web site.

Hope that this helps add to your knowledge base!

HAFE FUN, Otherwise you might as well call it WORK!

Beau

 

Hmmmm.. The Sarantel antennas don't require a ground plane and I don't think the active patch antennas that I use do... Though I do install them. I measure them to fit the Toughbook though... Not the antenna. I'll have to test different sizes to see what happens.

 

If I'm not mistaken, the design of both the radial helix antenna used on the Sarantel and that of most of the popular patch antennas in use today DO include an integral ground plane; this is why they are SO effective in such a small package.

mnem
Pizza is not a good ground plane... however, with the addition of rocket motors, it CAN BE a tasty AERO-PLANE...

 

Thank you for the great write up. I wish you were my neighbor, I'd be picking your brain all the time.

I have a couple of questions for ya.....

1. I have a D-Link DIR-655 at my home. We have just recently finished the pool in our amenity area which accross the street from my house. I can sit down there and pick up my signal with about 3 bars, some places I can't. I have my Dlink in the front office, with one of there antenna extensions. I then ran the antenna to where it sits between the window and screen. In other words, I have that antenna as far out as I can!

How may I improve the signal strength in the situation? I am sitting up higher than what the pool is, if that helps a little.

2. At the Bureau they are starting to install 1 antenna on the vehicle. How can they do that, and still allow ud to reach everybody? Are they like multi Hz antennas?

 

Toyo... Are you still using the stock antenna? I replaced my stock 5dB antenna with a 9dB antenna and picked up enough to cover my whole property and then some... And my router is buried in the middle of my office behind the desktop LCD.

Of course you must know the secret password...

 

One of the first questions that I have is: are you utilizing the N standard and/or the MIMO technology on this router?

The DIR-655 uses a technology called MIMO (Multiple-in, Multiple-out). What this does is use polarity differences in the signal (Vertical polarity & Horizontal Polarity) to share the available bandwidth (20Mhz bandwidth in the 2.4Ghz range). :GEEK: For a complete explination of the bands and how 802.11b/g/n and 802.11a/n does this, there is a great explanation here. While me writing out the b/g/n and a/n might have confused some, please know that the N (or N-Draft technically) versions of WiFi has much more to do with HOW & HOW MANY signals are used and processed and has almost ZIP to do with the actual frequencies (b/g/n used 2.4Ghz and a/n uses 5.8Ghz).

The antennas that come on the D-link are called point to multi-point antennas. These are made for a single antenna to be able to handle connections from multiple different points in a 360° area. While this is perfect for most applications, for you, it a draw back when you are trying to get distance instead of coverage.

SO, here comes the issue that you have to decide how to handle. To utilize the MIMO features of your router, you need to have three equal and exact antennas on the DIR-655. These antennas need to be matched for the software algorithm to accurately determine direction, range, and polarity. By altering the antenna on the DIR-655 you have possibly invalidated the ability for the router to handle multiple channel communication.

My next question is, do you spend a lot of time pool side?? If you do, I would consider adding an b/g access point via cat5e cable, directly to the 655 router and then hook a directional panel antenna up to the access point aimed at the pool area (giving you about 180° coverage). If you have a b/g router lying around that you are not using, this can be set-up for AP use. When setting up the AP, all you need to do is match everything exactly as you have it with the 655. Wireless name, channel, security, WPA codes… EVERYTHING has to be exact. What this will allow for is the un-interrupted hand-off of your computer from one wireless device to another without you even knowing it. The computer will automatically choose the strongest signal and connect there.

Since Panel antennas can be expensive, a very viable, but more focused, alternative is a Yagi antenna. We used these very successfully for the first couple years of WiFi coverage of the local faitgrounds, and still use them for narrow point coverage areas such as wireless bridging. The best part is that most really good Yagi antennas are usually under $50. MFJ makes quite a few inexpensive WiFi Yagis that you can find here.
The other option you have is, if there is currently decent enough coverage for the area or you are only in the area occasionally, is to leave the set-up as is and see how well it works out.

Yes, these antennas are multi-Mhz antennas that use a tuning stub to match the frequency. In some cases there is an antenna tuner when there is a large spread of non-matching (harmonic) frequencies that have to be covered. As an example, I have a 160ft dipole (80ft per side) that hangs from North to South in my yard. This antenna has been specifically cut and tuned to match the 80M band for HAM radio. With the antenna tuner that is in my Kenwood TS-2000 radio, I can tune that antenna all the way to a 6M antenna (3.6Mhz to 51Mhz). As you can see, this is quite the range for an antenna to cover and would be impossible without an active antenna tuner. I have never tried it, since I have a great VHF antenna, but supposedly the external antenna tuner that I have will do this as well as tune up into the VHF/UHF range.

If you have any questions, please don’t hesitate to drop me a PM!! However, if it's something that you think the forum could benifit from, please post here!! Enjoy it!!

Beau