DRDO-LRDE’s Airborne Radar Architectures: Plank vs Tile

India’s radar development has reached a point where it can be meaningfully categorized into two clear technological paths. On one side, we have the plank TRM architecture, which has been the workhorse of LRDE’s Uttam AESA radar for the Tejas program. On the other, we see the emergence of the tile TRM architecture, which is shaping the future radars meant for the Su-30MKI upgrade and the AMCA.

From a distance, these may look like two different hardware designs. But in reality, they represent two different philosophies of how to scale radar performance, manage bandwidth, and prepare for future challenges in electronic warfare.

The Plank Approach: Reliable, Familiar, and Incremental

Plank-based radars, like the Uttam AESA, are essentially built around long, strip-like TRM assemblies. This design lends itself well to dipole antenna elements, which are simpler, easier to integrate, and already proven in many fighter radars worldwide.

The numbers tell a clear story:

• The Tejas Mk1A carries 912 GaAs-based TRMs.

• The early Tejas Mk2 prototypes stayed at 912 but with a refined layout.

• The newer Mk2 design bumps this up to 968 TRMs, and possibly moves to GaN modules.

On paper, this looks like a modest improvement. But the real difference is in material choice. GaN technology allows higher power output, better efficiency, and improved thermal handling. So, even a small increase in TRM count could translate into noticeable performance gains in detection range and resilience against jamming.

For Tejas, the plank solution is more than enough. It gives India an indigenous radar that is relatively compact, reliable, and good for light fighters that don’t need extremely large apertures.

The Tile Approach: Modular, Scalable, and Forward-Looking

The tile TRM architecture is a more recent direction, and it reflects LRDE’s ambition to move into radars that can keep pace with global trends. Tiles are compact, replaceable blocks populated with TRMs, and importantly, they can host Vivaldi antennas. These antennas are inherently wideband, giving much greater flexibility in waveform design, electronic attack, and low-probability-of-intercept modes.

Here, the contrast is much sharper:

• For the Su-30MKI, the Virupaksha AESA packs 2400 GaN-based TRMs. That is more than double the density of the LCA radars, and it’s necessary for a large fighter that is expected to track and engage multiple targets at long range. Interestingly, a prototype is also being tested with the older plank design, which suggests LRDE is keeping options open while scaling production.

• For the AMCA, the tile-based array houses 1528 GaN TRMs. The circular layout fits better with a stealth nose cone, and the focus here is on efficiency, bandwidth, and compactness rather than sheer TRM count.

The key point about tiles is that they are modular. Fault isolation is easier—if one tile fails, it can be swapped without disturbing the entire radar. This makes long-term fleet management much simpler.

Why This Matters

The shift from plank to tile is not just about engineering choices—it reflects India’s radar doctrine.

• Plank radars are good for lightweight fighters where size, weight, and cost are more constrained. They are also easier to certify and integrate quickly, which explains their adoption in Tejas Mk1A and Mk2.

• Tile radars, with their wideband capability and scalability, are clearly aimed at platforms that need more—whether it’s the heavy Su-30s, which form the backbone of the IAF, or the future AMCA, where radar stealth and electronic warfare are central to survivability.

The other key thread is the transition from GaAs to GaN. It is fair to say that India has taken a cautious, staged path here. GaAs modules were a necessary first step, but GaN is where real competitiveness lies. The fact that both the Su-30 and AMCA radars are designed around GaN shows confidence that India can manufacture and sustain this more advanced semiconductor technology.

Next Steps

The way LRDE is structuring these radar families suggests a tiered approach:

• Plank (Uttam family) → for Tejas Mk1A and Mk2, providing reliable, indigenous AESA capability for lightweight fighters.

• Tile (Virupaksha / AMCA family) → for the Su-30 upgrade and AMCA, where bandwidth, range, and electronic resilience are higher priorities.

In practice, this gives India a balanced ecosystem: a radar architecture for each class of fighter, and a clear pathway to scale TRM numbers and antenna types depending on the role.