wifi using passive radiators (microflect)

To a degree. The 5.8 Gig feed horn radiators are cut for 5.3, 5.4,

5.7, and 5.8 Gig...so depending how close the "6 GHz" radiator is cut to 5.8 Gig WiFi will determine if the array will work.

On the other hand, if you are referring to the dish reflector and using your own feed horn radiator...then yes, it will work.

I should have provided a link to the Microflect website.

I've noticed these used in the boonies, though I found one on Volmer Peak in Berkeley (ca). My guess is the size of the panel is relevant to the efficiency in refecting the energy. So the 802.11a might be close enough for government work.

You find these buggers on hills where there is power, i.e. a more conventional point to point relay could be done. My guess is the telcos rather not have to ride an articat to reach the sites in the dead of winter.

snipped-for-privacy@sushi.com hath wroth:

Here's an excerpt from my comments to someone that wanted to install a passive reflector 600ft away:

Do you have any idea how large the passive reflector will need to be at 600ft in order to make this useable? At 2.4GHz, the highest gain antenna is about 24dBi with a 7 degree beamwidth. At 600ft, that beam is 74ft wide. With a 45 degree tilt angle, that's a 103 x 103 ft diameter reflector. Anything less will result in corresponding loss of signal. Half the size = 1/4th the area = -12dB loss.

Basically, the problem is that your antenna has to "illuminate" the reflector efficiently. If the radiation angle is too wide, most of the RF will not hit the reflector and is lost.

I don't have a clue what you're trying to accomplish, but if it's to avoid installing a directional antenna and coax on a tower, it's called a periscope antenna.

Periscope antenna: |

Wade calls them "flyswatter" reflectors. Most people call them eyesores. | Ah, found the catalog: | 7MBytes and 118 pages. Lots of nice pictures.

Here's an Excel spreadsheet that claims to do passive repeaters (back to back antennas) and passive reflectors.

Anyway, both passive repeaters and reflectors are rather lossy unless you have extremely narrow beamwidth antennas at both ends. If you have RF gain to burn or waste, then give it a try. If not, I don't think it will do much for you. Perhaps if you explained what you're planning to do and perhaps supply some numbers?

My bad...I missed the "passive" part in your OP, so disregard everything I said about feed horns and radiators. Read the Valmont PDF on passives.

I know what a periscope antenna is:

well as the fly swatter. [No longer used by telcos.]

This is mostly a curiosity to me if these existing structures could be exploited.

Now the issue of illumination is interesting. I've found a few of these passive radiators in the FCC database. They illuminate the reflector from about 20 miles away. So either the antenna is a freakin' telescope or they just blast the signal.

one of these paths. You need to use the "network" link in Google Earth. This is the one with the double passive reflectors I put in the other post.

snipped-for-privacy@sushi.com hath wroth:

Wrong. Those are 4ea horn antennas. The waveguide feed is at the bottom. The horn expands to match the waveguide to the impedance of free space. The end of the horn has a 45 degree reflector at the mouth of the horn. Because the reflector is PART OF THE ANTENNA, it's automatically in the near field, and does not have any of the overspray loss found in reflectors located some distance away.

What's cool it to shove a microphone into the waveguide at the base of the horn. Amazing what you can hear.

Yeah, the horns are rather broadband. Just change the waveguide size for different frequencies. It would have roughly the same gain as a dish antenna of the same diameter as the mouth of the horn.

Or, they accept the loss. Give me some numbers and I'll grind them (time permitting).

Exploited how? Using an existing reflector? Tying into it?

Exploited? I assume you mean would they be of any use to try to experiment with them and see if you bounce your own signal around.

No, not really. Unless if you find it useful to place your own equipment in the exact line of their equipment..AND use similar power levels as they do.

Just bouncing a signal off of their gear for yucks. That kind of exploit. Nothing sinister.

"Bill Kearney" hath wroth:

If you look carefully at the photograph, the 4 horns do NOT have any waveguide connected to the bottom of the horns. Install a waveguide to coax transition, run a few feet of LMR-400, plug in your laptop, and go for a new DX record.

On the webpage where I put those photos, I declared this to be a very low power system.

They haven't done a wifi shootout at defcon in a few years as far as I can tell. I think after doing 125 miles with huge dishes, they figured that was the limit. I was going to suggest a wifi shootout with reflectors. Less distance, but more planning involved.

There are a few of these no longer used telco horns around central Nevada. One presumes there is no aligning needed if you can find a pair of unused horns.

I guess there is no cost to maintaining them. Usually the need to strobe a facility encourages the owner to take it down.

Getting back to 802.11b, I've detected beams of wifi in the middle of nowhere with kismet. It turns out there are wireless internet services in these remote areas. If we could see RF, we would need shades.

snipped-for-privacy@sushi.com hath wroth:

It was apparently an inter-carrier exchange site. It's still listed on:

What I found amusing was the gain for the big dish, and the tx power used, probably exceeded FCC limits. For example, the 2005 version at:

shows a 300mw xmitter, and a 12ft diameter dish. They're official line is that it was using amateur radio power limits.

Ma Bell is still depreciating some of its older assets. I know of at least one CO that has racks of crossbar switches waiting to be fully depreciated. I suspect there may also be some step-by-step switches, but I don't know of any offhand.

Use sunblock to prevent RF burns.

I'm not sure you can depreciate an asset that you clearly aren't using. Now if they ebay those old horns, well, they would look mighty ham sexy on my roof. ;-)

Careful, you might find them green skinned and purple hooter alien gurls attractive.

snipped-for-privacy@sushi.com hath wroth:

I don't recall any requirement to actually use what I purchase and depreciate. I'm still depreciating some of the junk test equipment and computer goodies that I've purchased for company use, and rarely if ever, use those.

Also, some of the telco hardware probably costs more to dispose (hazardous waste) than it does to just leave in place.

For those that are not into ham radio (or hams that are still living in the stone age) see:

Some of my friend and their cars appear on various pages as examples of dress code violations and vehicular hazards.

If I installed one of those horn antennas on my roof, my neighbors would immediately blame me for everything from TVI to automobile engine failures.