Product Line, Customer and Geographic Information - Result of Product Line Revenues and Gross Profits (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Results of operations by segments
REVENUES	$ 20,590	$ 21,731
GROSS PROFIT	8,658	7,864
Operating Segments [Member] \| Antenna Products [Member]
Results of operations by segments
REVENUES	15,088	17,764
GROSS PROFIT	4,861	5,198
Operating Segments [Member] \| Test & Measurement [Member]
Results of operations by segments
REVENUES	5,535	3,999
GROSS PROFIT	3,785	2,670
Corporate, Non-Segment [Member]
Results of operations by segments
REVENUES	(33)	(32)
GROSS PROFIT	$ 12	$ (4)

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration