Navaid models: a few suggestions for improvements

[drPhibes]

Being a professional in the field (15 years in the r&d dept of a major navaid manufacturer), I have a few suggestions for improvements for the 3d models used in the various DCS maps. All maps use the same models, so I assume that they are part of a standard asset pack for the terrain developers. These are minor details that only the biggest nerds will notice, but I thought I'd let you know anyway.

 

Localizer antenna:

The localizer antenna used in DCS is clearly meant to be a log-periodic dipole antenna (LPDA), but the 180° phase shift between each radiating element in the antenna means that it can’t be constructed like the model in DCS, where the staggered up/down position of the radiating elements is symmetrical about the center line of the antenna. This website has a nice figure showing how a LPDA is constructed:

https://3g-aerial.biz/en/online-calculations/antenna-calculations/logperiodic-lpda-antenna-online-calculator

This is also how all the different localizer LPDAs used by the major ILS manufacturers are constructed. Other than the misplaced radiating elements on one side of the antenna, the general shape of the antenna is fine(-ish).

 

 

DVOR:

 

• The diameter of the counterpoise (the elevated platform that the antennas are mounted on) is a little small (~25m in DCS, while they are ~30m in real life).
• The 48 sideband antennas should be mounted equally spaced in a ring with a diameter of 13,5m, but in DCS it is ~9m.
• The sideband antennas are the wrong type. In DCS they are regular horizontal dipoles, but all DVORs use alford loop antennas. The shape of the radomes can vary, but they are usually cylindrical or square with a conical or pyramid top. Here are a few examples (with dimensions in the PDF):

        https://www.antennas.com/?s=dvor&post_type=product

        https://net-com.bytom.pl/anteny_lotnicze/AT-DVOR%20011%20en.pdf

 

• The DVOR carrier antenna is missing in DCS. It should be mounted in the center of the counterpoise, and it should also be an alford loop antenna.
• The DME, antenna which sits in the center of the counterpoise in DCS, can be mounted coaxially with the carrier antenna in some cases, but it is also common to place it at the edge of the counterpoise. The lattice mast should not be poking up through the counterpoise.

 

Edited May 28, 2024 by drPhibes

[drPhibes]

I found a DVOR (without DME) at Kutaisi, which has a much more accurate model. It's basically good enough to pass for both a DVOR with and without a co-located DME.