R&S®FK855C3 HF Antenna Tuning Unit
For matching R&S®Series 2000 HF radio family to antennas used in stationary and shipboard applications
Silent tuning over the entire frequency range from 1.5 MHz to 30 MHz
Before the ATU can be used, it must be connected to an antenna to "learn" its characteristic. Learning takes place in a user-defined frequency range in the HF band (1.5 MHz to 30 MHz).
The ATU "learns" the antenna characteristic by receiving tuning data for a maximum of 1500 predefined frequencies. Once the tuning data for these frequencies is known and stored, the typical ATU setting time is less than 5 ms.
The advantage for the user is low probability of intercept (LPI), since ATU frequency setting is performed very quickly and without any emission of RF power.
Repeated tuning
A change in environmental conditions may slightly alter the actual antenna tuning data as compared to the stored data.
The quality of antenna matching is therefore checked during operation by means of an integrated VSWR measuring device. If the required VSWR (<1.5:1) is not attained, the ATU can be retuned in less than typ. 100 ms.
