Spider Antenna & Gen. Antenna Q's

Any one ever tried this spider antenna?

I was curious if any of you RF junkies could tell me if using a full wave length on that antenna would be beneficial (and if the ground reflectors would need to be a different length or how to calculate that)?

I'm looking for an antenna for my van and dock that is:
1)cheap
2)good performance
3)interesting
4)DIY

I love building stuff like this, and the curious looks I get when using it.

TIA!

 

If you look at the date of that article (2002), that should give you some idea of how much antenna technology has advanced since then. That particular antenna was tuned for 802.11b only. If you really want a stubby style, try Googling for an short NMO style antenna. They are only about 3/4" in diameter and about 2-3 inches tall costing about $25-30. They also come in several frequencies so you can use the same style for many different radios/scanners. They even make them that are multiple frequency.

 

Two such examples are: 2.4 GHz Mini-Mobile Wireless LAN Antenna and DUAL BAND MOBLE OMNIDIRECTIONAL WIRELESS LAN ANTENNA.

 

The spider is just what I found that looked good. I like the idea of DIY antennas for thier interesting nature, and look (usually). I did a grey-hoverman for my digital tv antenna and it's the best I've used.

I'm just looking for a good 6+dbi gain omni antenna for my van.... any other suggestions? I don't mind it being a bit longer. I found some from hong kong for $12 or so, but don't want to wait 30 days to get'm.

Thanks!

 

One, be careful of the antennas from Hong Kong as they are not always as advertised and two, there are so many antenna outlets here in the states you should have no trouble finding exactly what you want. You just need to surf the net a bit and you won't spend much more on one that really works rather than the ones from SEA. I have done quite a bit of research on antennas for cb/scanner/cell and there are a ton of them out there in any length you want.

 

For not much more work you could make a stacked collinear antenna that would have far more gain thin this little omni.

Grab a copy of the ARRL Antenna Manual and have a go at it. I have built these inside of PVC tubing for durability and weather resistance.

 

I had looked at the collinear antenna at the gumph site, and found a few more links. The way I figure, if I use rg8/lmr400, as per the specs, the antenna would be about 13.5 inches long. would I see better gain if I doubled it (16 segments instead of 8)?

Also, I found a local shop that I'll check out tomorrow. I have always just got stuff online, as it's almost always more cheap than walking out of a store (convenience fee I suppose).

Thanks guys, i'll report back on what I get.

 

Patience is a virtue.
And after waiting some odd months, my local radio shack is moving, and has a wicked random stuff clearance section. How bout a 3dbi wifi antenna with base & rubber boot, 9' lead, and tnc (that screws, btw, right onto my car dock), for

$1​

 

And that will do what? I would think if you hooked that up to your CF-29 that your performance would go down. It is VERY hard to beat the stock wifi antenna system unless you are going for long-range performance... (IE Cantenna system) In which case... That would be the wrong antenna...

 

Yes! I agree;
right up till you put the toughbook in a big metal van... I think.

I get really sketchy connections in my van, so for $1, I figured WTH, why not?
I usually get a "poor" signal and need to lift my 29 up will above the dash (close to shoulder height) just to get a low end "good' signal from a hotspot like chickfila or MCD's. If it sucks, for $1, I'll use it on my tv dish biquad.

bet that would look funny mounted to my a-team astro (i'm still amazed at how $20 in spray paint can can tickle my inner child)(in a totally not pedophilic way)



It's a work van. don't judge me...

 

Uh... Okay...... Do youo still have the stock wifi card or have you moved up to the Engenous card? The Engenous 600mW will (in most cases) double your signal....

 

Yeah, i could use it, but not yet. I've been concentrating more on wwan. I I have a 775 now, and added the panny wwan antenna. I'm moving up to an 860 and then focusing on my bubkis touch screen. I have my wrt54g running at 250 mw and get a great signal at home (I can pick it up bout 1000' away)(my house sits up cause I live in a bad flood zone). I'm all over the place...

 

The problems you have at these frequencies, 2.4 GHz, 3.6 GHz and 4.9/5.0 GHz, is line loss. The cheap coax and multiple connectors that folks will use, specially in the pigtail will quickly lose your gains if you are not careful. I have a stacked collinear antenna on a mag mount that I use. I stick it on my roof. The coax is good stuff that is almost 1/2" thick. A bear to route, but worthwhile.

I see a huge gain in performance, with this setup over the lid mounted, particularly as this gets and keeps the antennas above the cars "beltline" and in the green house.

If I go to a car mount I will replumb the Wi-Fi connection through the pass-through.

The other option that avoids the line loss problem nicely is to use a USB Wi-Fi device and put it in a radome of some kind on the roof.

I have seen several of these for sale from companies like Flytech.com. They are high power, 600mW to 1Watt and have a place to mount a high power antenna.

This will do the trick.

 

Do something like this:


Then add a 9dbi Magnetic roof mount ant...

 

yeah, NO. the antenna I bought for $1 had no performance gain so far. I'll try a couple more times, just to make sure.

On a side note, I did get a Dish Network Super Dish, BNIB, for $5. Biquad here I come!

Is that cantenna diy? nice!

 

Nopers, actually bought that one.
I got a biquad on my desk and a dish under, doubt i'll ever mount it.
I bought a rubbermaid container just large enough to cover the biquad, painted the inside black with vinyl paint and put some foam in to protect the quad.

 

I've made a very useable vehicle-mount WiFi by mounting a Thumb-drive form-factor WiFi adapter inside a piece of 1 1/4" PVC like many HAMs will do to make a mobile Dipole or Monopole antenna. On mine, I used a 5m USB extension and a 10ft piece of PVC to get maximum elevation. By attaching it to the back door hinges with heavy duty Zip Ties and allowing the cable to exit the tube at the top edge of the back door, I had just shy of 3m of cable inside my van to reach the workbench inside. I dunno if that would reach for you. Of course, you CAN always make your PVC Pipe shorter to get more cable; in theory, you ONLY need to be above the ground plane of the roof to get adequate signal.

My setup cost me $8 for the PVC pipe & cap & 5m USB cable; I had the WiFi adapter, silicone sealant, and PVC cement on hand.

You CAN go longer than 5m by using an Active Repeater USB cable; but then you lose the economy factor.

If you're feeling froggy and don't mind ugly, you could take the same WiFi stick and "silicone it to death" to a USB extension cable; then once it dries, zip tie the whole mess to your FM Radio antenna. As long as you keep the top 1/2 of the WiFi stick above the tip of the antenna, it shouldn't provide any interference to the USB stick; though I don't know whether the WiFi stick would mess with your radio. The difference in frequency bands says they should decouple pretty well; but there's digital circuitry inside the WiFi adapter that COULD still play h3ll with your radio. I'd do some Empirical Engineering (try it & see if it works) before I get crazy with the silly-cone on that one.

mnem
Food for thought, thought from food.

 

I think the engenius card will probably do it for me.... I have other things to get straight on my 29 before I worry bout it.

OH, here is a good price on a repeater cable, btw.

I love that site, they have all kinds of good random crap

 

The real trick here is to just get the antenna outside the vehicle.
Any antenna at any frequency throughout time works better in the air than inside a metal cage.

The other thing is that this is some of the oldest technology around.
Antenna design fundamentals are straight forward and have not changed mush through the years.
This is also an area where experimenting is popular because it is so inexpensive to create new designs.

I second the idea to get your hands on the ARRL Antenna Book.

But the most important thing is to get the metal in the air.

Ed