That little bit you mentioned about the antenna being "mounted to a military fighter craft" is obviously a fairly important consideration.  It is safe to assume that you really have no choice but to find a qualified military airborne product (otherwise the cost will be astronomical).

There are plenty of companies in this market.  I'm not sure if any of them have made a 2300 MHz antenna, but they could probably cut down an existing design with minimal NRE.  The price will still be significant, but there's usually not much option for making do with unqualified products.

Some leads...
 EDO Corp: www.nycedo.com
 Chelton
 Trivec Avant
 www.google.com/search?q=military+antennas

In general, their websites are useless and you'll need to make some phone calls.

Problem seems to be wanting to run the antenna length below
1/4 lambda.....
If you have a good matching circuit it is possible but you are going to have very poor efficiency.

Quarter wavelength at 2200 MHz (13cm band) is only about 1.3 inches.  Therefore, 2 inches is plenty of room.

You could try a Sensor Systems S65-5366-1S which is 1.04 inch high, full MIL rated but has a TN connector.  Otherwise look at any of the commercial telemetry antennas.

Suggestion: Visit
http://www.tsa-orlando.com/antennas/10332.html
for more info

This is a rather trivial design & I would recommend the following:

1)  If you have the the height (about 2 inches required), use a sleaved dipole design.  This will give you broader coverage, good bandwidth, and work well off of the ground plane of the vehicle.

2)  If you want a low-profile design (more robust for your application), design a simple PIFA.  This can also work off of the ground plane of the vehicle.  For 2.3 GHz, you will probably need a height of 4-8 mm (depending on bandwidth requirements).  If it turns out that your structure is too large, you can load the antenna w/ a plastic carrier (example PC, PC/ABS, etc) which will reduce the size by ~20%.

The above antennas assume that you want wide beam coverage w/ average gains of -1~-4 dBi.  If you need a narrow beam w/ high-gain, you'll need to look at other options.