Why is brick architecture preferred for high-power phased arrays?

High-power T/R modules (5-20 W per element) generate significant heat that must be efficiently removed. Brick architecture provides a direct thermal path from each PA to a cold plate or heatsink located behind the module, keeping junction temperatures below 150°C even at high duty cycles. The perpendicular orientation also allows longer module housings that accommodate higher-voltage GaN devices and associated bias circuitry without being constrained by the half-wavelength element spacing.

What is Brick Architecture? | RF Module Integration

Q: What is the difference between brick and tile architecture?

In brick architecture, RF modules are oriented perpendicular to the antenna aperture plane, extending behind each radiating element like bricks standing on end. In tile architecture, the RF electronics are integrated into thin planar layers that stack parallel to the aperture, like floor tiles. Brick offers better thermal management because each module has direct access to a heatsink, and failed modules can be individually replaced. Tile offers a thinner overall profile and potentially lower cost at high volume, but thermal management is more challenging because heat must be conducted laterally to the array edges.

Q: Can brick modules be field-replaced?

Yes, field replaceability is one of the primary advantages of brick architecture. Each brick module is a self-contained unit with standardized RF, DC, and digital interfaces (typically blind-mate connectors) that can be inserted or removed without soldering. This reduces mean time to repair (MTTR) from hours to minutes and allows maintenance without taking the entire array offline. Military phased array radars like the AN/SPY-6 use brick architecture specifically for this operational availability advantage.

Definition & Concept

Brick architecture is a phased array module packaging strategy where transmit/receive (T/R) modules and associated RF electronics are oriented perpendicular to the antenna aperture, extending behind each radiating element like bricks standing on end. Each "brick" is a self-contained functional module housing a complete RF signal chain (PA, LNA, phase shifter, attenuator, and T/R switch) with standardized blind-mate connectors for RF, DC power, and digital control interfaces.

This architecture dominated early active electronically scanned arrays (AESAs) and remains the preferred approach for high-power military radars where thermal management and field replaceability take priority over array thickness. The perpendicular orientation provides each module with a direct thermal path to a cold plate or forced-air heatsink, enabling efficient heat removal from high-power GaN PA stages dissipating 5-20 watts per element. The modular construction allows individual brick replacement in the field without soldering or array disassembly, reducing mean time to repair from hours to minutes.

Key Design Parameters

Element Spacing Constraint:

d ≤ λ / 2 ≈ c / (2f)

At 10 GHz: d ≤ 15 mm, constraining brick cross-section to ~15 × 15 mm

Thermal Resistance (brick to cold plate):

θ_jc = ΔT / P_diss ≈ 5 – 15 °C/W per module

Array Depth: Brick depth typically 80-200 mm (vs 10-30 mm for tile)

Brick vs Tile Architecture Comparison

Parameter	Brick	Tile	Panel
Module Orientation	Perpendicular	Parallel (planar)	Hybrid
Array Depth	80-200 mm	10-30 mm	30-80 mm
Thermal Management	Excellent (direct)	Challenging (lateral)	Good
Power Handling	High (5-20 W/elem)	Low-Medium (1-5 W)	Medium (2-10 W)
Field Replaceable	Yes (blind-mate)	No (soldered)	Partial
Manufacturing Cost	High (per module)	Lower (batch PCB)	Medium
Weight	Heavy	Light	Medium
Typical Application	Military radar	5G base station	SATCOM

Practical Application

The AN/SPY-6(V) radar for the US Navy uses brick architecture with over 5,000 GaN-based T/R modules arranged in a 4.3-meter aperture. Each brick module delivers approximately 10 W of peak transmit power at S-band (3.1-3.5 GHz) and can be individually replaced by a shipboard technician in under 5 minutes using blind-mate RF and DC connectors. The perpendicular orientation allows each brick's GaN PA to dissipate heat directly into a liquid-cooled cold plate behind the array face, maintaining junction temperatures below 150°C at full power with the ship operating in tropical environments (45°C ambient).

Frequently Asked Questions

What is the difference between brick and tile architecture?

Brick modules extend perpendicular to the aperture (deeper but better thermal). Tile electronics stack parallel (thinner but thermal challenges). Brick enables field replacement via blind-mate connectors; tile requires soldering. Brick dominates military radar; tile dominates 5G base stations.

Why is brick preferred for high-power phased arrays?

Each brick has a direct thermal path to the heatsink, handling 5-20 W per element efficiently. The perpendicular orientation accommodates larger GaN devices and bias circuits without being constrained by half-wavelength element spacing.

Can brick modules be field-replaced?

Yes, blind-mate connectors allow individual module replacement in under 5 minutes without soldering. This is a key advantage for military systems where operational availability is critical, as in the AN/SPY-6 naval radar.

Brick Architecture