Product Line and Geographic Information - Result of Product Line Revenues and Gross Profits (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Results of operations by segments
Revenues	$ 21,681	$ 19,842	$ 39,388	$ 37,348
Gross Profit	$ 9,942	$ 9,521	$ 18,280	$ 17,736
Gross Profit %	45.90%	48.00%	46.40%	47.50%
Operating Segments [Member] | Antennas & Industrial IoT Devices [Member]
Results of operations by segments
Revenues	$ 15,562	$ 13,910	$ 27,285	$ 25,370
Gross Profit	$ 5,175	$ 4,973	$ 8,922	$ 8,892
Gross Profit %	33.30%	35.80%	32.70%	35.00%
Operating Segments [Member] | Test & Measurement Products [Member]
Results of operations by segments
Revenues	$ 6,414	$ 6,118	$ 12,619	$ 12,201
Gross Profit	$ 4,834	$ 4,609	$ 9,422	$ 8,905
Gross Profit %	75.40%	75.30%	74.70%	73.00%
Corporate, Non-Segment [Member]
Results of operations by segments
Revenues	$ (295)	$ (186)	$ (516)	$ (223)
Gross Profit	$ (67)	$ (61)	$ (64)	$ (61)