“Field Day” is this weekend for ham radio operators. In the radio hobby, this is a set weekend every year where ham guys set up remote operations, usually in a public place such as a park, and operate from there. The idea is so that the public can see how they operate, ask questions, and even try it out without needing to buy gear or even get a radio license.
While anyone can participate, radio clubs usually do it as a group effort, where they pick a location, set up tents/generators/antennas/etc and have multiple radios going. In addition, clubs often designate “cooks” to grill up some food while they’re busy playing radio, and eating good is just as important as getting contacts.
If you see a group, and/or are curious about amateur radio, feel free to approach them and ask questions – thats the idea of this after all! Not only can you ask questions, but most hams/clubs will have a “Get On The Air (GOTA)” station set up for visitors to try out. Also note theres no age limits as well.
Fridays are usually the start of setup, with setup usually finalized by Saturday morning. The official “contest” (who can make the most field day contacts) starts at 2pm Saturday and goes for 24 hours until 2pm Sunday. By then things are usually winding down and the stations are being packed up, so your best bet is Saturday afternoon, or earlier if you can lend a hand setting up.
If you’re interested but not sure where to find a field day setup, use this locator page to find some near you: http://www.arrl.org/field-day-locator
Last but not least, this page offers a more detailed explanation of field day and what it entails: http://www.arrl.org/field-day
Have fun and 73!