wifi antenna ranging/aiming

[BillH]

I've spent a few hours now looking for the best laser to help aim my personal wifi antennas (flat) at each other. The distance is about .5 miles. I found a green laser at dragonlaser, but thought I'd ask here before finishing.

The green lasers at Green Laser Pointers : Dragon Lasers include a 'viper' at 35mw. Is it your opinion that this laser would show a dot at this distance - during the day? at night?

I'll only be using this periodically, to keep the antennas aligned. It's my first laser...

Also - should I get a pair of red goggles? If so, please give me an idea of a 'safe' pair - I saw $5 gogles at amazon and they looked incredibly cheap (read: unsafe).

Many thanks -

/Bill

 

[ElectricPlasma]

This is actually a pretty innovative. When you say, "(flat) at each other," did you mean perpendicular? If so then you'll have to find a way to put the laser at 90 degrees to the antenna. Once you've got that done you could use a beam expander to give your laser a better divergence, so that it will cover the 1/2 mile. Your best bet for a BE (beam expander) is probably Sanwu's 3X BE, mount that one any >100mW green laser and that'll be a good enough visibility. But if you're going to do this during the day you'll want a brighter laser. A good place to get reliable and approved goggles are survival laser, look for the Eagle Pair laser safety glasses.

 

[BillH]

I'm talking about 'flat' antennas. Yeah, I'll put together a wood frame that will snugly fit over the antenna, and use some plastic clips to temporarily mount the laser to the wood frame. I don't know what a 'beam expander' is except from the context of your statement - you make it sound like instead of expanding the laser, it will actually make it tighter - for the longer distance, I'm guessing?

I saw a few youtube videos showing lasers at 100mw burning and cutting. I don't want to burn or cut the remote wifi antenna, just be able to light it up :-D

Do I really need that powerful of a laser?

Thanks alot for replying!

/Bill

 

[ElectricPlasma]

I'm talking about 'flat' antennas. Yeah, I'll put together a wood frame that will snugly fit over the antenna, and use some plastic clips to temporarily mount the laser to the wood frame. I don't know what a 'beam expander' is except from the context of your statement - you make it sound like instead of expanding the laser, it will actually make it tighter - for the longer distance, I'm guessing?
...

Yep, you almost got it on the nose. The BE expands the beam but creates better divergence so while the diameter of the beam is larger, the divergence is more narrow. You might want to do some research here on LPF, maybe PM a couple of the guys who are good with optics, off the top of my head RedCowboy and Alaskan comes to mind. It's not cheap but still affordable, the BE from Sanwu is $60 IIRC. :yh:

I saw a few youtube videos showing lasers at 100mw burning and cutting. I don't want to burn or cut the remote wifi antenna, just be able to light it up :-D

Do I really need that powerful of a laser?

Thanks alot for replying!

/Bill

Even a 5W laser will not be able to burn at the distance you're aiming it at (arguable but in your case true). You don't need that powerful of a laser but it's my recommendation, others may say brighter and some might say not as bright. I feel like the sweet spot for things like this is right around 100mW, because at that power level you can get single mode diodes which as easier to work with (they don't diverge as much) but are a good brightness. Something like the green Nichia diodes might be an option, though that's got it's own price tag too. $60 for just the raw diode, and ~$100 for whole the module including the diode, driver and lens. Prices are from DTR's laser shop, check it out: https://sites.google.com/site/dtrlpf/home/diodes/100mw-nichia-ndg4216-515nm-laser-diode

 

[BillH]

Thanks again, @ElectricPlasma - I hadn't considered working with 'raw diodes' such as you linked at google. Would it not be easier for me, (MS in computer science but I'm purely a software kind of guy) to work with a 'handheld' version of this? At this point in my life I'm humble about my abilities, and very familiar with my weaknesses :-D

Would mentioning @RedCowboy and @Alaskan cause them to be notified of activity in this thread? I'll also poke around looking for private message capability that you are saying is here somewhere....

 

[steve001]

I've spent a few hours now looking for the best laser to help aim my personal wifi antennas (flat) at each other. The distance is about .5 miles. I found a green laser at dragonlaser, but thought I'd ask here before finishing.

The green lasers at Green Laser Pointers : Dragon Lasers include a 'viper' at 35mw. Is it your opinion that this laser would show a dot at this distance - during the day? at night?

I'll only be using this periodically, to keep the antennas aligned. It's my first laser...

Also - should I get a pair of red goggles? If so, please give me an idea of a 'safe' pair - I saw $5 gogles at amazon and they looked incredibly cheap (read: unsafe).

Many thanks -

/Bill

Certainly at night. As for broad daylight operation probably not. You didn't mention which way these antennas will be facing, east west, north south or somewhere in between? How much surface area the antennas have? You said flat. What does that actually mean? A solid flat surface, perforated? You probably won't be able to see a dot at that distance in broad daylight without a binocular or spotting scope. It would be better to do this task when lighting conditions are low. You won't need goggles for the task. at that .5 mile distance the laser will appear as a bright light.

 

[ElectricPlasma]

Thanks again, @ElectricPlasma - I hadn't considered working with 'raw diodes' such as you linked at google. Would it not be easier for me, (MS in computer science but I'm purely a software kind of guy) to work with a 'handheld' version of this? At this point in my life I'm humble about my abilities, and very familiar with my weaknesses :-D

Would mentioning @RedCowboy and @Alaskan cause them to be notified of activity in this thread? I'll also poke around looking for private message capability that you are saying is here somewhere....

I don't believe mentioning them would be notified of this thread, not entirely sure though. For your PMs, there is an access link at the top right corner of the website, right under where it would say, "Welcome, BillH". This will be where you can see if you have any new messages, or if you can't find it this link will take you to your private messages: http://laserpointerforums.com/private.php

As for the diodes, if you can find a laser already built that suits your needs then go for it, it would make things easier. I would rather build one so I'm familiar with it but at the end of the day it really comes down to personal preference. :yh:

Edit: Steve, I think he's trying to have one antenna transmit via the laser to be able to put a dot on the other antenna which will show that it's aligned.

 

[steve001]

Edit: Steve, I think he's trying to have one antenna transmit via the laser to be able to put a dot on the other antenna which will show that it's aligned.

Sounds like it.

 

[Benm]

I'm not really sure what kind of antenna you are using there, but a simple laser unit should be more than good enough to align antennas pointing at eachother.

Realistically even a $1 red laser module will have a divergence of at most a few mrad. Planar antenna's, yagi's and all those have much wider opening angles (several degrees at best), so if the laser is spot on the antenna definitely is within say 90% of what it could get.

The only 'problem' with low powered lasers is that you'd have to have someone on the receiving side to confirm seeing the laser brightly while adjusting the antenna on yours.

You may get to the point where the divergence of the laser is larger than that of the radio signal when using (big) dish antenna's, but i guess you will not be using those for a signal path of half a mile.

At half a mile you could even align things from the sending side looking for the laser reflection at half a mile using something like a 100-200 mW red laser, if you do it at night.