Empty Vessels Make Waves!

Published Date
01 - Mar - 2006
| Last Updated
01 - Mar - 2006
 
Empty Vessels Make Waves!

There are a few people who won't let a technology or resource limitation cow them down. They try and tweak with vengeful perseverance until they find a way out. Meet Ravi Sharma, a final year B.Com. student in Bangalore who has set up a Wi-Fi network using low-cost TV cables and a simple yet brilliant directional antenna made from trashed utensils!

Making one's own antenna may not be unusual for Ham radio veterans, but a lossy cable and used utensils for a Super G Wi-Fi computer network? Yes, that's what this soft-spoken 20-year-old has done!

The Challenge
Like they say, necessity is the mother of all inventions: in Ravi's case, he wanted to network the computers in his father's drug distribution godown and the administration office, which are about a hundred metres apart.

A conventional wired LAN was out of the question, since the area is thickly populated-any kid with a blade or a pair of scissors in his itchy hands could bring the network down. The next thing to consider was to go the wireless way.

Cost immediately became a concern because of the distance between the buildings, and also because of the distance between the godown computer and the terrace from where line-of-sight could be achieved. Ravi could not afford commercial setups that cost upwards of Rs 50,000. He therefore started trying to figure how to build his own setup.

The Solution
To keep costs low, Ravi used an ordinary RJ58 TV cable, which costs about Rs 10 per metre-the typical low-loss cables cost about Rs 400. This in itself is some serious cost cutting! With such a cable, he was able to get just about enough signal strength to take data to an access point located 50 metres away on the terrace. From here, the access point had to talk to the WLAN card on the other machine 100 metres away. Ravi could not get this working immediately with the omni-directional antenna that came with the WLAN card. Rather than invest in a commercial high-gain directional antenna, he thought of making one himself.

He figured that all he needed was an old aluminium utensil. He placed the antenna in front of the inner curve of the utensil. Thus was formed a brilliant yet simple zero-cost directional antenna with an estimated 20 dB gain! Ravi similarly placed another scrapped aluminium vessel behind the 5 dB antenna of the access point. The range was increased by at least 50 per cent with the use of the vessels, which act as reflectors. He has also weather-proofed them by applying a coat of a anti-rust paste.

Getting his setup working was difficult-first, he could not find a connector to connect the RJ58 cable to the WLAN card's antenna port. At a point where many would have given up and opted for more expensive cables, Ravi again made one himself! Mind you, that's no easy task! With the cable connected at one end, it was only half the problem solved. To attain line-of-sight, he had to place the antenna high on his terrace, and doing this needed some serious wall climbing skills. In his own words, "The biggest challenge was to climb up on both terraces and check the transmission rate with my laptop... I had to stand at the edge of tall buildings, and could have fallen 40 metres with even the slightest of pushes. Planting that antenna was risky."

Thankfully, we were provided with a makeshift ladder when we went there to check it out!

The Prize
After a few bouts of trial and error, Ravi managed to align the antennas and ping each machine from the other. It was then time for jubilation: he finally saw his dad's EAI (Enterprise Application Integration) solution working from both machines. This meant someone sitting in the administrator's office could easily check and operate on inventory maintenance in the godown. PHARMA ASSIST, the EAI solution Ravi's father uses, comes with multi-user support across a network.

Ravi has managed to set up videoconferencing and has enabled sharing of inventory data between the two machines with a throughput of about 80 Mbps. This is commendable, considering that the theoretical maximum of 802.11 Super G is 108 Mbps. Ravi admits, however, with a sigh of relief, that he has been lucky not to have interference from other Wi-Fi networks-something Wi-Fi (especially Super G) system administrators are plagued by.

Entrepreneurship, Anybody?
What started off as a hobby to help his dad's business has blossomed into a prospective business plan. Ravi is currently working on a plan to make higher-gain antennas to increase the propagation distance of Wi-Fi.

The road ahead for this is not easy. Making a project for his own use is one thing; product placement and marketing is a different ballgame altogether. For this, Ravi has teamed up with XITECH Solutions, a company that provides networking solutions, to help him explore business opportunities. Work continues on the tech front in his own testing centre in a Bangalore suburb.

Ravi's ideas have many takers, including a Government of Karnataka project for which he made a presentation of his ideas. The project-called GramPatra-aims to give villagers land record information using Wi-Fi, as part of a larger e-governance plan.

There is a broad smile on Ravi's face when he says he is working on finding loopholes in the current system at GramPatra and developing high-gain directional and omni-directional antennas for the project.

Of late, he has been approached by network solution providers asking if he could work on some turnkey projects.

"My plans for the immediate future are to take Wi-Fi installations to apartments, societies, hotels, and the corporate world. This would be on the existing technology, and I would work on the R&D of my topology and come up with solutions offering longer ranges, especially for specific corporate needs," says Ravi.

The fascination with the building of one's own antenna seems universal. Network geeks in the US have come up with what they call a "cantenna" for Wi-Fi. The "C" simply stands for "can." A can of anything, but most popularly, an empty Pringles chips can! This, however, is another story for another time.

For Ravi, experimenting is a not a one-off thing. He had earlier designed a pollution-reducing add-on to two wheelers using calcium carbonate, which converts carbon monoxide to the less harmful carbon dioxide. That project had won him awards.

Jargon Buster 

Antenna Gain: The ratio of the signal, usually expressed in dB, received or transmitted by the antenna as compared to an isotropic antenna, when both are supplied the same power. An isotropic antenna is a theoretical antenna: if it existed, it would radiate a signal equally in all directions.

Directional Antenna: An antenna that radiates waves in only one direction, such that energy is not transmitted in unwanted directions.

Lossy Cable: A cable or wire in which a signal experiences considerable "loss" while being transmitted, meaning the signal strength is reduced at the end point of the cable.

Omni-Directional Antenna: An antenna that transmits signals equally in all directions.

RJ58: An inexpensive, coaxial TV cable suitable for cable TV transmission across short distances.

Super G Wi-Fi: An extension of the 802.11 g Wi-Fi standard, which transmits in the 2.4 GHz band and has a theoretical data transfer rate of 108 Mbps. 


Ravi comes across as an extremely unassuming person-it was only when his lecturer approached a news daily that he got the media attention his innovation deserved. Asked where he gets his ideas from, given his commerce background, he says "common sense," with no second thoughts and not so much as a blink of an eye. It's a pity this breed of sense isn't more pervasive!

The Costs 
Two WLAN cards                    Rs 4,000
One access point                   Rs 9,500
Connecting wire for 30 m       Rs 300
 
Utensils used as                    FREE!
reflectors 

Total: (Less than)                  Rs 15,000 

We wish Ravi all the best, and hope to see a lot more of the DIY spirit!


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