I agree that most WiFi applications are based on omni-directional (convoluted) aerials/antennae, but Directional WiFi aerials are available as shown here-

http://www.wifi-shop24.com/en/WiFi-Antennas?gclid=CK...

There was a recent thread on this forum about getting WiFi to a garden shed, obstructed by a thick line of conifer trees, two of those directional aerials may have produced a solution.

I am aware of co=linear arrays of dipoles, in excess of 100, operating in the 10 GHz / 3 cm band, producing extremely narrow beams.

most likely water company infrastructure - sewage pumping etc.

Another possibility is that it is for a local Cable TV system; and that the cabinets may have been there for some years.

With the change-over to Digital Terrestial TV, a more directional but broad (TV) band aerial is required to cover the range from about 400 MHz to 800 Mhz, so has become obvious with a newish pole/standard; and a more sensitive (longer) aerial at the top.

I understand that there were/are quite a few in the Valleys area, in-filling "shadow" areas.

====================

A465 Head of the Valleys road, as originally built - rather like doing "circuits and bumps" in a small plane.

Take off from one roundabout, climb up to the summit, then dive down to land at the next roundabout, "taxi" through it to take off again ... .

In reply to a post by eckiedoo:

I agree that most WiFi applications are based on omni-directional (convoluted) aerials/antennae, but Directional WiFi aerials are available as shown here-

http://www.wifi-shop24.com/en/WiFi-Antennas?gclid=CK...

There was a recent thread on this forum about getting WiFi to a garden shed, obstructed by a thick line of conifer trees, two of those directional aerials may have produced a solution.

I am aware of co=linear arrays of dipoles, in excess of 100, operating in the 10 GHz / 3 cm band, producing extremely narrow beams.

Interesting, I stand corrected.

They would never use a Yagi aerial (wideband or not) for wi-fi though, would they?

Edited by deleted (Mon 18-Feb-13 01:52:47)

Agreed that a Yagi aerial would be unlikely for WiFi, difficult to produce the physical parts and assemble them etc.

There is a fair chance though that a slot aerial design might be considered, and the convoluted "bent piece of metal" found inside Modem/Routers etc may reflect this-

http://www.antenna-theory.com/antennas/aperture/slot...

With the Laptops & Netbooks I have seen opened up, the WiFi aerials seem to be built in to the hinges.

The 100+ dipole aerials I am aware of, were of extremely robust design, for various reasons.

Regarding WiFi and its Broadband aspects, you may find the involvement of Hedy Lamarr (Hollywood Film/Movie Star 1940s) of interest, as WiFi uses similar Frequency-Hopping techniques-

http://en.wikipedia.org/wiki/Hedy_Lamarr

They would never use a Yagi aerial (wideband or not) for wi-fi though, would they?

yes, ideal for a client end pointing at an omni base station. Sometimes they live in a plastic tube so don't look like a yagi.

But not on the scale we're talking about here, i.e. the photos. To be big enough to incorporate the reflector, that's a massive plastic tube which wouldn't fare too well once the wind got up a little bit. It would be so impractical to incorporate a Yagi aerial into a modern wi-fi receiver, unless we're talking about home-made solutions with whatever resources can be gathered.

I think the point is that this is clearly a water cabinet, and tens of thousands of water and electricity "stations" use a vertically aligned Yagi pointing at the nearest (usually mainly TV) transmitter. Relatively close to me, but a bit out in the country, there are at least two electricity poles with switchgear on them, which have the same Yagis - presumably to set an alarm off somewhere in the event of a failure, or if an engineer has unlocked the massive padlocked lever and thrown it.

None of this is anything to do with fibre, or related "wi-fi" as we principally know it, and that was my point. It has been interesting though, I assume the Yagis in tubes you're talking about are smaller than usual?

indeed the aerial pictured is not wifi frequency as its was too big and somewhere in the UHF area by the look of it.

Here's a wifi example

In reply to a post by gazzyk1ns:

In reply to a post by simon194:

In reply to a post by Ribble:

May not even be a telco's cabinet . Have seen water companies use similar

It's most likely a water company remote monitoring setup.

Yes, a vertically aligned Yagi aerial is almost always water or electricity monitoring. In this case, from the fact that it's a small street cabinet, it would be water. The Yagi aerials will usually point to the nearest TV transmitter or relay, because that's where the water/electricity companies have sensibly placed their receivers.

That's right. In fact the utility companies use a part of the UHF band just below TV, about 410 MHz I think, the yagis you see will therefore have slightly longer elements, than the ones that are designed for TV reception, as well as being mechanically more roust than domestic models..