Product Request: A cheaper 5.x point to point parabolic dish

[NewBWiFiGuy]

Quick background: I'm currently building out a 802.11g based multipoint backbone for my Wisp. Since there are only 3 channels available for 2.4ghz WiFi. I want to start expanding my backbone using 802.11a.

Right now I can get a 2.4Ghz 24db gain 36" dish grid antenna from electro-comm.com for $65. Believe it or not, with maximum legal boost it is possible to reach 40-50mile links. This is pretty reasonable cost wise.

However here is the problem, there is NO reasonably priced 5.xGhz point to point antenna on the market. I don't know how people are supposed to build backbones/bridges using 802.11a when it costs a rediculous $400 for a decent 802.11a dish? It's $1000 for a high end one. Someone needs to release a low cost (around $100-$150) point to point long range 802.11a antenna for use in building reliable point to point links.

It's the old "chicken and the egg" problem. Every antenna vendor I talk to says, "oh well they can't price these 802.11a dishes low like the 2.4Ghz models because we don't sell enough of them". Well I'd think that if they took the leap of faith, put together a standard cheap antenna that performed well and priced it around $100 it would start selling quickly for WISPs and WiFi hobbyist...? Then with luck that antenna manufacturer would be producing enough quanity that they wouldn't be taking a profit hit?

I write this post in the hopes that I can garner some interest in getting the 802.11a bridging market going. As well as to help vendors understand that people are interested and want affordable products. If no one releases hardware that small business WISPs can afford, only few are going to buy the hardware. Another problem is that all the APs I find don't run in the 802.11a upperband range which I believe was meant for these higher power longer range links. I'm told that later this year some vendors will release some higher power upperband radios.

If I go ahead with my WiFi business, I could see myself building out a backbone grid of over (20) 802.11a radios. If a vendor builds a 4 channel bridge I could have over 150mbit feeding all my 802.11g hubs, but as is, it is completely impossible to do so. I am forced to use 802.11g links which don't have some of the Fresnel clearance Zone benefits (http://www.ydi.com/calculation/fresnel-zone.php) as 802.11a. As far as I understand it, while higher frequencies of 802.11a get obstructed more easily, they require less space between the top of your two antenna points before "hitting the ground" and reducing signal.

See this thread (http://forums.80211-planet.com/showthread.php?s=&threadid=1048) regarding my request for more bridging 802.11a systems.

[ccrum]

It really wouldn't be too hard to make your own if you are that interested. The nice thing about antennas is that they are not technology specific. What most antenna mfgs don't want you to know is that the materials required to make these antennas cost only a few bucks. It's the know how they are charging for, but once you know how, there is nothing stopping you from making your own. Dish antennas are about the simplest type of antenna to make because they are relatively frequency independant. Basically, they get their gain based on the size of the dish behind the feeder. It's essentially a surface area problem. It's the feeder that is different between different frequencies. I'd be willing to bet there is a supplier of 5 Gig feed horns out there that will sell in bulk. I'll dig around and see what I can find out. Maybe we can strike up a deal.

[NewBWiFiGuy]

Thanks for the reply. My only concern with the home grown solution is that I'd screw something up or not have a reliable setup. However if someone started building a home grown cheap 5.x Ghz high gain point to point antenna that was tested and proven I'd likely have no problem with it. It would have to be sold to more people than just me of course. I can picture myself spending a day trying to aim an antenna that is defective wondering what I am doing wrong :)

[ccrum]

Well it wouldn't necessarily be home grown. You would just purchase the dishes sperate from the feeder and assemble them yourself.

Ther eare some cheaper dishes out hter though. Try this link:

http://maxrad.terra-wave.com/Detail.bok?searchpath=d18e4017f12d25858462&category=MAXRAD&start=1&total=58&no=66

Price on it is 312.50

[sbwoodside]

You might want to check out the wireless-longhaul@openict.net mailing list:
http://openict.net/projects/wireless-longhaul/

From what you say I'd recommend that you try out 802.11g and use the 2.4 antennas ... what they say about volume is correct, and 802.11a isn't so popular really, esp. now that g is out.

simon

[ccrum]

The low popularity thing is what makes it great for backhaul....lots of people out there on 2.4 and not just WiFi. It's all interference though. FOund another link for some 5 gig dishes that may be a good price. They are running a 24.00 special on the 2.4 dishes right now, but htey don't ahve aprice listed on the 5 gig.

http://www.dbiplus.com/products.htm

[sbwoodside]

Hmm... I didn't realize that interference was an issue if there's a directional at both ends.

simon

[ccrum]

Interferenc is always an issue. If someone is near your sit with a 2.4 gig corless phone, any energy that reaches your dish gets picked up. Obviously the directivity of the antenna helps to provide a spatial filter, but it will still pick up any rouge signals that make it there. Also if you are on a tower and someone else sticks up a site near yours at the same elevation and chooses the same channels, you will most likely be off air rather quickly.

[NewBWiFiGuy]

sbwoodside, that mail list looks excellent. I just subscibed to it. Thank you.

As for interfearance with point to point with 2.4ghz getting used more and more. Say someone had a radio near your bridge running on the same channel - well I'd suspect that could cause your bridge to slow down as they danced around each other.

If it was cheap to use 802.11a you really have a cleaner space because the frequencies used for the long range 802.11a stuff are not near the same frequencies/power levels. The lower 802.11a (as far as I understand it) are supposed to be used for the "around the house" or campus network.

Your recommendation of me using 802.11g for my bridges is wise. Since, as my posts complain, there is no lower cost bridge solutions with 802.11a *yet*, I'm using Linksys WAP54G 802.11g radios in bridge mode. I just bought 6 units to build out a starter system. I'd still like to back those bridges up with 802.11a bridges if it became affordable.

CCRUM, I checked out the terrawave 5.8ghz dish. That's a better price than I've seen. Still it makes it difficult at that price. I need $100 vs $300. Something I may never get, but I am hoping.

I just visited the dbiplus.com site. I see the 5ghz antenna but their webmaster as the product brochure pointed to his D:\ drive. And they list no price. This doesn't instill confidence.

As for the home grown solution, I am not opposed - I might just have to do a little testing when I can afford the time and effort. Perhaps one of these 2.4ghz 36" dishes I have with a 5.xghz feeder could be built. I'd rather have a fully tested reliable OEM solution of course.

[Mikey]

Don't want to sound like a commercial. But thought it worth the reply to this thread. There are some low cost grids coming out for the 5GHz band. Nothing that's in stock yet. But check out Equinox RF (http://www.rfeq.com). They do grids for all sorts of frequency ranges. This is the company that owns the original Pacific Monolithics patent and has been making grids for several years. Only up till now all their antennas have been sold under different brand names, all OEM stuff. Electro-comm is the Equinox master distributor for North America. I know there are no 5.2GHz grids listed on the web site. As soon as I heard about them making grids for the 5Ghz band I asked about the mid UNII band 5.25-5.35. They weren't aware of any demand there, I made it clear that there sure is. "No Problem" they said. So look for them soon.

Mike Brownson, electro-comm

[NewBWiFiGuy]

Mikey, thanks for your reply. I'd rather have your info than worrying it being an advertisement.

So if I am reading you right you are saying is that these 5.xghz point to point antennas will soon be available and orderable via your company? And since the point of my post was price - they'll hopefully be comparable to the 2.4ghz parabolic dishes?

See my new note in this thread 802.11a high band radios and EIRP (http://forums.80211-planet.com/showthread.php?s=&postid=3413#post3413).

While your talking to them, some comparibly priced sector, panel, and omni 5.xGhz antennas would also be useful. So far I don't see many good 802.11a external antennas for the overall market. If we are supposed to start building mid range 802.11a hotspots and POPs that reach further than our property line we're going to need some better antennas that compare in price to the 2.4ghz ones.

[NewBWiFiGuy]

Another idea just hit me. This is not new and I think there are a few antennas out there that do this already.

It would be handy to have dual band 2.4ghz and 5.8x point to point antenna so for instance; say WISP operator Joe needs to build a 130mbit bridge. He could plug in two 802.11g radios and 2 or 3 802.11a upperband APs at each end and then plug those into a medium range SOHO switch to "bridge the bridges". All over a single pair of antennas.

Of course if by supporting multiple bands, it would lower the antenna's performance I'd rather use two separate units. Multiple APs can still be stacked on each antenna. I plan this for many of my 802.11a bridges far down the road.

Dual 2.4ghz/5.xghz antennas would also be useful for dual band APs.

[Mikey]

While I heven't seen any pricing yet, yes they should be comparable to the low cost grids for 2.4. Probably a little more because they need more wires in the grid so the 5Ghz signal doesn't pass through them.
And we were just talking about dual polarized and dual band antennas too. Don't know about those though, it's too early to say. I hope to know more about availability soon.
Mike B

[ccrum]

It all depends on how a dual band antenna was constructed. If you tried to use the same feed elements for the same band, you would definitely degrade the performance as you would have to have some kind of filter/splitter/combiner going on to get everything into/out of one feeder. If you used seperate feed lines and feed elements though, there shouldn't be a problem with using the same dish. Performance may suffer a slight bit due to neither of the feeders being at the exact focal point of the dish, but it would still be better than trying to use one element for both frequencies. I doubt that any mfg will consider it though as they want to sell as many dishes and feeders as they can.

[NewBWiFiGuy]

Mikey, I understand. Since your 2.4ghz parabolics are $60 for 5 (which I consider a fair price), if the 5.xghz solutions were within $20-$30 or so of that price I could deal with it. That would enable me to build a 2-way bridge for allot cheaper than the $600 ($300ea) that I've been seeing 5.xghz dishes go for.

I'm guessing the manufacturer is going to have to release a lower band 5.15-5.35Ghz antenna and an upperband 5.725-5.825 antenna if it's really going to be effective? I'd hope this would just be a feeder swap and the dish could be a standard part...? Now if we can just talk the FCC into upping the transmit power levels for upperband 802.11a 5.725-5.825ghz we can start using it for those really long links.! ;-)

ccrum, your probably right, it might be more performance/aiming trouble than it costs in performance. I'd rather pay a little more if the antenna performance was greater going with a separate antenna solution. If an antenna oem can do it thats great, if not then I can still make things work. Of course, if a tower provider charges a bunch more per antenna mount, it might swing the argument back in the other direction. That might make tip the scales for the WISP operator to use multichannel 802.11 upperband alone.

Thanks

[NewBWiFiGuy]

Just saw this news announcement (http://www.shorecliffcommunications.com/magazine/news.asp?news=2005) today:

http://www.shorecliffcommunications.com/magazine/news.asp?news=2005

New 5Ghz antennas. Wonder what prices we'll see.

[sidgrea]

For your review.

http://www.wwc.edu/~frohro/Airport/Primestar/Primestar.html


Hope it helps.


Ron

[NewBWiFiGuy]

Good news! Looks like Electro-comm and Equinox came through on some affordable 5.xGhz parabolics. Here are the specs listed in their catalog.

5.2-5.85Ghz 24dBi 14" dish $62
5.2-5.85Ghz 26dBi 18" dish $71
5.2-5.85Ghz 29dBi 24" dish $84
5.2-5.85Ghz 32dBi 32" dish $109
5.2-5.85Ghz 36dBi 39" dish $199

No mention yet of beam width or front to back ratio. I'd guess somewhere around 8-15deg beam width and 18-25dB FB ratio..

Now that these are out I think I've decided on my hub and spoke model for hilltop rural sites. I'm going to use dot11net's Lan Master 5.8Ghz Antennas (http://dot11net.com/antennas.asp) on the towers, and these new equinox 5.2-5.8ghz models at the customers premises. I'll vary the size of the parabolic based on distance and line of site at the customers location.

Looks like 5Ghz networking is becoming an affordable option as I hoped.

- Aaron Smith
PowerGuide@cableone.net
http://aaronsmith.net/PowerGuide/

[NewBWiFiGuy]

FYI I talked to Electrocomm today.

The new parabolics are for sale in catalog but not shipping just yet. They are trying to get the feeders just right since they cover from 5.2ghz to 5.8ghz.. which excites me cuz they are ready for the new 5.470-5.725 middle band :)