Operating Segment - Product Category (Details) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 26, 2017	Dec. 25, 2016	Sep. 25, 2016	Jun. 26, 2016	Mar. 27, 2016	Dec. 27, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 26, 2017	Mar. 27, 2016	Mar. 29, 2015
Revenue and Gross Profit from External Customers
Revenues	$ 122,602,900	$ 147,198,400	$ 134,633,800	$ 128,860,000	$ 114,154,100	$ 139,510,700	$ 142,353,300	$ 134,664,000	$ 533,295,100	$ 530,682,100	$ 549,619,000
Gross Profit	$ 25,937,600	$ 29,968,600	$ 28,755,600	$ 27,106,000	$ 23,018,900	$ 29,453,400	$ 30,511,700	$ 28,981,900	111,767,800	111,965,900	117,638,500
Base station infrastructure
Revenue and Gross Profit from External Customers
Revenues									209,869,000	206,604,000	224,135,000
Gross Profit									54,280,000	51,610,000	55,732,000
Network systems
Revenue and Gross Profit from External Customers
Revenues									87,222,000	83,480,000	96,399,000
Gross Profit									11,897,000	12,893,000	13,549,000
Installation, test and maintenance
Revenue and Gross Profit from External Customers
Revenues									31,851,000	34,936,000	41,790,000
Gross Profit									5,921,000	6,607,000	8,351,000
Mobile device accessories
Revenue and Gross Profit from External Customers
Revenues									204,353,000	205,662,000	187,295,000
Gross Profit									$ 39,670,000	$ 40,856,000	$ 40,007,000