MENLO PARK — Dozens of ham radio operators invaded Bedwell Bayfront Park Saturday with a fleet of mobile broadcasting stations and towering portable antennas for national Amateur Radio Field Day.

At 11 a.m. sharp, members of the Palo Alto Amateur Radio Association settled down in four different field stations and began to contact thousands of other stations across North America. It is a combination test of readiness to assist in disasters and a competition to see who could make the most contacts.

"This is the biggest ham radio event of the year," said Doug Teter, an association member who coordinates the local event. It is sponsored nationally by the Amateur Radio Relay League, a 160,000-member ham radio association.

Teter said the exercise "is principally about getting us practice in deploying our equipment in the field in unusual and less than optimal settings. It makes it a little more challenging. There are no fixed facilities, no power, no water. The whole thing runs on portable generators."

Last year, the Palo Alto association scored first in its class across the nation with more than 5,000 contacts, third overall in California and ninth overall in the U.S. The group hoped to repeat that victory this year, "or improve on it," Teter said.

Four different antennas were scattered inside a 1,000-foot perimeter, according to the rules of the competition. Two transmitters were for voice communication, and two for Morse Code. A small computer-controlled antenna on a mobile satellite tracking station also scanned the skies for a polar-orbiting satellite to make contact with other ground stations.

All the gear, the ham operators, their friends and the occasional curious jogger were gathered on top of the highest hill in the park. The site is between two salt flats, which help boost the signals. "It's almost like we have an amplifier," Teter said.

Field Day also helps promote the organization, said Jim Thielemann of Menlo Park. "People come by and ask questions," he said.

Professor Bob Iannucci from Carnegie Mellon Silicon Valley at NASA Ames Research Park in Mountain View was on hand with some of his master's and Ph.D. students, along with an acquaintance through church, Chongho Lee, who was recently licensed as a ham operator.

"Ham radio is a great thing," Iannucci said. "It's a great learning experience, and it serves the public."

While Field Day tests the emergency preparedness of ham clubs across the continent, the competition is key for the Palo Alto area chapter, according to its members.

"We're a bit into the contest side of things," said chapter president Kristen McIntyre, an Apple (AAPL) engineer who lives in Fremont. "We hope to talk to as many stations as we can across North America."

McIntyre, an expert in Morse Code, will spend all night Saturday tapping out messages from one of the mobile stations.

"I get on 40 meters (a radio band) and just plow through the night," she said. "Just feed me coffee."

The 24-hour exercise ends Sunday at 11 a.m.

"One of the best aspects of amateur radio is the people," McIntyre said. "I love the technology -- I'm an engineer, so it's my thing, but the people are fantastic."

The local radio association has about 180 members, she said, and 60 to 80 of them turn out for regular meetings in Palo Alto.

It meets on the first Friday of every month at the Cubberley Community Center in Palo Alto. Its website is http://paara.org.

Contact Pete Carey at 408-920-5419. Follow him on Twitter.com/petecarey