The Ship Model Forum

Hi All - I see that there are a number of antennas on this ship. There are longwire antennas
between masts running along the deck and there are smaller antennas on a mast on the island,
including a small crossed-loop forward of the bridge. Is there a reference that points out what
the various antennas are for? I know that the ship had LW, MW, and SW (HF) transmitters and
receivers but I cannot reference detailing the antennas. (I am interested in the ship during the
Battle of Coral Sea before it was fitted with radar.)

Thanks,

Sam

The round loops in front of and on top of the bridge are RDF (radio direction finding) loops, used to track radio signal transmissions. The small tripod with a whip antenna atop the bridge is a Type 90 wireless telephone antenna (there are at least two of them up there.) Outboard of the bridge on the starboard side, strung between latticework tripod supports attached horizontally to the bridge, and running up to the top of the main mast (not seen below, except for the insulators hanging above the deck between the RDF loop and the bridge front) are more radio wireless antennas, similar to those strung between the four lattice masts further aft along the edges of the flight deck.

HTH.

Hi Dan - Thanks. Do you have any further information on the RDF loops or longer antennas?

Sam

What kind of information are you seeking?

Hi Dan - Sure, I am seeking details on exactly which antennas would go to which radio to get a better understanding of how the ship operated.
One can find pictures of American carriers in which each antenna is pointed out with what each did. I am looking for something similar with this
ship.

For instance, those loops on the deck. There are multiple loops. Given the time frame and size, those loops look like they are for medium and
low frequency. Could they rotate?

With regards to the long antennas in the back, what exactly is each for? I believe they were moved down during flight operations, but could
they still be used?

Best,

Sam

Hi, Sam -

So, there's not a ton of information available that I know of, at least in English.

A description of how the RDF loop/detection system worked can be found in one of the postwar US NavTech reports. See: https://www.fischer-tropsch.org/primary ... 20E-05.pdf

Some more information on IJN radio antennas is here: https://www.fischer-tropsch.org/primary ... 20E-17.pdf

AFAIK, the long antennas were used for communication with Japan/land and ship based HQs. Reception (and transmission) were more effective when these masts were raised, which was the typical state excepting flight operations. Perhaps more helpful is a recent discussion on the j-aircraft.com shipboard, which discussed IJN shipboard communications. See: https://www.j-aircraft.org/smf/index.php?topic=19012.0

Hey Dan - Thanks for all that it was real good. The discussion in j-aircraft was most useful. I have been trying to join that site without success for quite some time now.
I cannot see the images but it was interesting that at the end they seemed to be talking about a antenna on a reel that trailed out of the back of the ship
with the end being a float. I am not sure if that is a detail on models or not.

I am trying to determine with antenna(s) the ship used to transmit on 215 and 500 kHz. According to JM-118 page 45, they used both frequencies.

Which leads me back to those long masts on the ship. It would be interesting to know their length. Whether they are individual wires or whether
they are connected in a "tee." This might give you a better idea of what I am looking for: https://musickpointradio.org/amateur-ra ... z-antenna/

Similar to the above website, I would think that the Japanese would have some sort of tuning box for these antennas. I am not sure if that is modeled or
not.

Sam

I don't have time to review that discussion, but I'm quite sure no such cable was trailed behind a ship, much less be shown on a model.



The illustration below is of the masts aboard Ibuki. Measurements of other vessels is, AFAIK, pretty non-existent, but the assumption has been that most masts were close to this size and distance from each other. There may have been some variations, particularly among the earlier carriers, but solid numbers are hard to come by. The rigging schematic might be simplified.

Hi Dan - Thanks, this was brilliant and very useful.

Sam