F-16 ADF question

[nilsko]

While checking out the several F-16A/B variants (blocks etc.) I also came across the F-16 ADF / Block 15 variants which used to be in service by the AMI (leased from the USAF) and still in operational use by the ANG. One of the most distinctive features is the "bulge"on the tail which houses the hydraulic accumulators of the HF subsystem (more info (among other sources) here: http://www.f-16.net/f-16_versions_article14.html).

This is all nice and dandy, but I was wondering why this version is equipped with HF antenna's whereas usually only VHF/UHF radios are present. Can someone enlighten my in the actually application of this HF system and why it's used in this F-16 variant?

[Flyboy]

As the usage of uhf/vhf is limited to the visual horizon, one get dependant on relay stations for communication. Hf has a better range, so if an intercept moves you over water ( toward the southern part of the mediteranean...) you can stay in contact with command without the depenancy of an awacs or satalites. Bombers and long range patrol use it all the time..,

[Bennie]

As the usage of uhf/vhf is limited to the visual horizon, one get dependant on relay stations for communication. Hf has a better range, so if an intercept moves you over water ( toward the southern part of the mediteranean...) you can stay in contact with command without the depenancy of an awacs or satalites. Bombers and long range patrol use it all the time..,

The range of VHF radio is approximately 1.2 times the square root of the altitude in feet (result= Nautical Miles)... Don't know if there's a large difference with UHF, but you'd have to be low and far away from the Italian coast not to be covered by it....
The distance between Rome and Sardegna is roughly 165NM as the crow flies... and if you put a transmitter/receiver on both sides.....

[pjotrtje]

Of course the HF transmitter was not needed for Italy, but it was necessary for the role the F-16 ADF was envisaged to perform in the USA and Canada. There's large areas (in Northern Canada mainly) where UHF and VHF are at the limit of their capabilities.

And the reason the Italians operated them? They were reasonably available, quickly, at a limited cost, with the right armament.

[nilsko]

Thanx for the background info. I am particulary interested in why HF radios where used for the ADF version, but pjotr's explanation makes perfect sense..

[Richard from Rotterdam]

I don't think the ANG still uses the ADF anymore though. Haven't all the Air Defence units swapped their A's for C's?