Operating Segment - Product Category (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 24, 2017	Sep. 25, 2016	Sep. 24, 2017	Sep. 25, 2016
Revenue and Gross Profit from External Customers
Revenues	$ 145,083,500	$ 134,633,800	$ 285,094,300	$ 263,493,800
Gross Profit	29,923,100	28,755,600	59,089,900	55,861,600
Base station infrastructure
Revenue and Gross Profit from External Customers
Revenues	59,448,000	52,502,000	118,518,000	104,897,000
Gross Profit	14,086,000	13,453,000	28,143,000	26,881,000
Network systems
Revenue and Gross Profit from External Customers
Revenues	29,180,000	21,461,000	53,017,000	39,891,000
Gross Profit	3,921,000	3,421,000	7,750,000	6,319,000
Installation, test and maintenance
Revenue and Gross Profit from External Customers
Revenues	7,679,000	6,881,000	14,671,000	15,636,000
Gross Profit	1,433,000	1,376,000	2,852,000	2,944,000
Mobile device accessories
Revenue and Gross Profit from External Customers
Revenues	48,777,000	53,790,000	98,888,000	103,070,000
Gross Profit	$ 10,483,000	$ 10,506,000	$ 20,345,000	$ 19,718,000