A rugged precision locking mechanism holds the antenna in place and forms a reliable RF connection to the handle. A ferrite sheathed cable, which does not distort the directional characteristics of the antenna even at low frequencies, provides the RF link from the handle to the IDA basic unit. This improves the achievable accuracy of direction finding. The transfer function of the handle including the cable with the preamplifier activated and deactivated is measured during production and stored in an EEPROM in the handle. The basic unit reads this data automatically via the control cable when the handle is connected to it and uses this for frequency response correction.
No additional batteries are needed to power the active antenna handle. The handle is powered directly from the basic unit via the control cable. The handle is therefore lighter, and no separate battery is needed that might need replacing during a long-term measurement. The Li-ion battery in the basic unit is hot swappable, i.e. it can be replaced while a measurement is in progress without the instrument switching off.
The IDA basic unit automatically detects the antenna type and polarization direction through the control cable and disables the frequency ranges not covered by the antenna to avoid unnecessary direction-finding errors.
The handle contains a precision position-compensated electronic compass, which transmits data to the basic unit through the control cable. The compass is adjusted in site during production, so it does not indicate a false bearing because of the handle. The user does not need to make any further adjustments. The local declination (angle between geographical and magnetic north) can be entered numerically on the IDA basic unit if required. The basic unit itself contains a second compass, which enables electronic maps to be easily oriented towards North in the IDA display. Any necessary correction value for the magnetic declination at the current measurement location can also be recorded.
The handle also contains position sensors that detect the elevation and polarization of the antenna. The elevation and polarization are important elements when determining the direction of the signal source by manual bearing. In contrast, the elevation and polarization need to be kept constant during rotation when generating a polar diagram using a horizontal scan. The audible level is a useful tool, which signals deviations with an audible tone, so you don't need to look at the instrument display.
Perhaps trivial, but extremely useful in practice: The ability to start, stop or correct the measurement with the press of a thumb on the antenna handle. You only have to press the Save button on the basic unit to store the direction-finding data when you are satisfied with the result.