"I think it's being — I wouldn't say demanded — but I think it's almost expected," Sommerhof said.

Woodbine-based Mid Atlantic Contracting, the project's general contractor, has been a TESSCO customer since opening in 1995. Fred Chandler, Mid Atlantic's vice president, said the stadium upgrade was complex and he appreciated the way the company handled the logistics.

"When we took the project on, preseason and special events were already in the works," he said. "There was no extra space down there. So they needed to know how we were going to sequence the project and bring everything in at just the right time."

TESSCO started life as Towson Engineering Sales and Service Co., a manufacturers' representative founded by Barnhill's father in 1952. Barnhill bought it in 1975 and turned it into a "total source" distributor, a company where wireless-industry customers could get everything they needed. (At first, it was wireless as in two-way radio and citizens band radio.)

Barnhill said his experience as a manufacturers rep suggested that one-stop shopping would resonate with companies.

"I saw how costly it was for me as a rep, as well as for the customer, to have multiple credit applications, multiple purchase orders," he said.

TESSCO's early days as a distributor were tenuous, Barnhill said. He and his wife, Janet, accounted for two-fifths of the workforce. It wasn't long before they had to choose whether to sell their house to plow the money into the business or have Barnhill go get a job somewhere else.

"We made the decision to sell," he said.

That turned out to be a good move, even though it meant house-sitting for a year and a half — with a young child — until they had enough money to rent. In 1981, the company supplied cables and antennas for one of the country's first cellular test sites, located in the Baltimore-Washington area. More cell business followed.

TESSCO's manufacturers worried that cellphones were a fad, like CB radio. But Barnhill said he was a believer.

"I saw the opportunity of wireless communications," he said.

Companies have tried to acquire TESSCO since then, but so far Barnhill has resisted the call — to large investors' annoyance.

Discovery Group, a Chicago investment firm that was TESSCO's largest outside shareholder in 2010, went public with its frustrations that year after it said TESSCO didn't even respond to several suitors. Discovery later offered to buy the company itself for $15.50 a share — and got a chilly no-thanks.

"The Board of Directors concluded that the proposal is grossly inadequate," the company said in a 2010 securities filing.

Part of the company's appeal is that its business model isn't straight middle-man, even with the products it buys and resells. TESSCO says it can help customers design wireless systems, configure products such as antennas, put every part and tool required for the project in one box and ship it directly to the installation site.

Rein, walking through the company's bustling Hunt Valley distribution center, passes by a massive inventory that ranges from fuse kits to drills to tape measures.

It's one of two TESSCO distribution centers — the other is in Reno, Nev. — and it alone handles more than 4,000 orders each workday, with over 100,000 pieces of product and about 120,000 feet of cable between them. Work goes round the clock from Monday through Friday, with weekends reserved for catch-up if needed.

The company also handles early prototyping for Ventev in Hunt Valley — the actual manufacturing is done in Reno and through contractors based around the world. TESSCO says it looks for niches that don't directly compete with the products it sells that were made by other manufacturers, though that could range from unique technology to different packaging.

New Ventev products include a combination wall/car charger due out in October and a cellphone case that has a backup battery built in. Barnhill, stopping in at a recent presentation about the products at the company's headquarters, snagged one of the "Powercase" backups for his iPhone.

"I was starting to hyperventilate," he said. "I left my charger at home."