Mystery antenna is in the left wing?

[Learjetter]

Gang,

1977 G model

Pulling some new wingtip lighting wiring behind leading edge of left wing and ran across some old RG58 coax connected to some kind of antenna box mounted to leading edge of left wing, just inboard of wing tie-down. Box mounted to leading edge which appears to be fiberglass or some kind of laminate for about 8 inches square. Very professional job, I never even noticed the very slight ridges in the paint until close inspection. Forgot to take pic…will try to remember to add a photo tomorrow.

Aluminum Box itself is maybe 6”w x 2”d x 5”h, mounted with 8 very rusty cap screws and six Phillips screws. Haven’t yet removed it since it’s very securely mounted. No writing or label of any kind is visible.

The other end of the coax went down the leading edge to the fuselage and a connector. Inside the cabin the coax went forward under the panel and was not connected to anything, just tied up and marked with old blue masking tape (nothing written on tape).

Aircraft was owned by a sheriff dept for awhile, but no form 337 is in the records…no logbook entry that I could find. Service manual and parts manual searches were fruitless.

Current theories include:
- some kind of radar antenna that can tx/rx thru fiberglass or laminate?
- something used by early Cessna RNAV equipment?
- some kind of flat VHF antenna for ILS/GS or comms?
- something law enforcement uses that connected to a handheld or floor mounted device?
- early form of lightning detector?

Have any of you run across such a thing? Any ideas what it is?

-LJ

[Skymaster337B]

Probably an ADF wire antenna connection.

[Learjetter]

The aircraft had ADF provisions in right wing, with wire antenna to right vertical fin.

[hharney]

Is there any kind of "Bump Out" on the leading edge of the wing where this antenna is? Can you see it from the outside?

[Kim Geyer]

It’s a glide slope antenna
That’s what the parts catalog says

[Learjetter]

Kim solved the mystery!. It’s a factory glideslope antenna. Figure 5, item 29e in the ‘73-‘80 parts catalog. Missed it during my original search of the manuals. Thank you!