Note 1 - Summary of Operations and Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares
Research and Development Expense, Gross \| $	$ 7,316	$ 8,025
Customer Funded Research and Development Expense Included in Cost of Goods Sold \| $	$ 1,369	$ 1,220
Weighted Average Number Diluted Shares Outstanding Adjustment, Total (in shares)	193,568	396,536
Number of Operating Segments	2
Share-based Payment Arrangement, Option [Member]
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total (in shares)	526,244	899,041
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	690,919	642,751
Restricted Stock [Member]
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total (in shares)	26,665	31,666
Customer Concentration Risk [Member] \| Revenue Benchmark [Member]
Number of Major Customers	2
Customer Concentration Risk [Member] \| Revenue Benchmark [Member] \| Large Defense Primary Contractor, 1 [Member]
Concentration Risk, Percentage	17.00%	12.00%
Customer Concentration Risk [Member] \| Revenue Benchmark [Member] \| Large Defense Primary Contractor, 2 [Member]
Concentration Risk, Percentage	6.00%	14.00%
Customer Concentration Risk [Member] \| Revenue, Segment Benchmark [Member]
Number of Major Customers	2	2
Customer Concentration Risk [Member] \| Revenue, Segment Benchmark [Member] \| Two Customers [Member] \| Battery & Energy Products Segment [Member]
Concentration Risk, Percentage	20.00%	15.00%
Customer Concentration Risk [Member] \| Revenue, Segment Benchmark [Member] \| Two Customers [Member] \| Communications Systems Segment [Member]
Concentration Risk, Percentage	38.00%	64.00%

Represents the amount of R&D included in cost of goods sold that is customer funded.

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The gross costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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