Business Segments - Product Category (Details) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 25, 2016	Dec. 27, 2015	Dec. 25, 2016	Dec. 27, 2015
Revenue and Gross Profit from External Customers
Revenues	$ 147,198,400	$ 139,510,700	$ 410,692,200	$ 416,528,000
Gross Profit	29,968,600	29,453,400	85,830,200	88,947,000
Base station infrastructure
Revenue and Gross Profit from External Customers
Revenues	52,193,000	51,571,000	157,090,000	161,669,000
Gross Profit	13,857,000	13,381,000	40,738,000	41,139,000
Network systems
Revenue and Gross Profit from External Customers
Revenues	25,242,000	22,922,000	65,133,000	66,541,000
Gross Profit	3,186,000	3,717,000	9,505,000	10,200,000
Installation, test and maintenance
Revenue and Gross Profit from External Customers
Revenues	9,633,000	9,851,000	25,269,000	27,481,000
Gross Profit	1,594,000	1,687,000	4,538,000	5,184,000
Mobile device accessories
Revenue and Gross Profit from External Customers
Revenues	60,130,000	55,167,000	163,200,000	160,837,000
Gross Profit	$ 11,332,000	$ 10,668,000	$ 31,049,000	$ 32,424,000