Operating Segment - Product Category (Details) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 24, 2017	Dec. 25, 2016	Dec. 24, 2017	Dec. 25, 2016
Revenue and Gross Profit from External Customers
Revenues	$ 146,260,300	$ 147,198,400	$ 431,354,600	$ 410,692,200
Gross Profit	29,599,800	29,968,600	88,689,700	85,830,200
Base station infrastructure
Revenue and Gross Profit from External Customers
Revenues	57,282,000	52,193,000	175,800,000	157,090,000
Gross Profit	13,280,000	13,857,000	41,423,000	40,738,000
Network systems
Revenue and Gross Profit from External Customers
Revenues	24,024,000	25,242,000	77,041,000	65,133,000
Gross Profit	3,420,000	3,186,000	11,170,000	9,505,000
Installation, test and maintenance
Revenue and Gross Profit from External Customers
Revenues	9,255,000	9,633,000	23,927,000	25,269,000
Gross Profit	1,759,000	1,594,000	4,611,000	4,538,000
Mobile device accessories
Revenue and Gross Profit from External Customers
Revenues	55,699,000	60,130,000	154,587,000	163,200,000
Gross Profit	$ 11,141,000	$ 11,332,000	$ 31,486,000	$ 31,049,000