| 摘要 |
The present antenna mast is constructed to telescope in response to pneumatic pressure. For this purpose a bottom tubular section has a pressure inlet and each further tubular section has a lower end fitting as a piston into the next lower section. Each piston has a passage for a gas under pressure into the next higher section. The upper end of the uppermost section is closed. The antenna is retracted by venting the bottom tubular section.
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