SPRADJ6 November   2026 AWR1243 , AWR1443 , AWR1642 , AWR1843 , AWR2188 , AWR2243 , AWR2544 , AWR2944 , AWR2944P , AWR6443 , AWR6843 , AWRL1432 , AWRL6432 , AWRL6844 , AWRL6888 , IWR1443 , IWR1642 , IWR1843 , IWR2188 , IWR2243 , IWR2944 , IWR6243 , IWR6443 , IWR6843 , IWRL1432 , IWRL6432 , IWRL6432W , IWRL6843 , IWRL6844

 

  1.   1
  2.   Abstract
  3. 1Introduction
    1. 1.1 What is a mmWave Radar Antenna?
    2. 1.2 Features of mmWave Radar Antennas
      1. 1.2.1 Fundamental Antenna Parameters
      2. 1.2.2 Fundamental Antenna Array Parameters
    3. 1.3 Antenna Type Selection
    4. 1.4 Critical Sections of Antenna
      1. 1.4.1 Source
      2. 1.4.2 Feeding Network
      3. 1.4.3 Radiating Element
    5. 1.5 Antenna Array and Pattern Selection
      1. 1.5.1 Virtual Antenna Array
    6. 1.6 PCB Material Impact on Antenna Performance
  4. 2Antenna Design Flow
    1. 2.1 End Application Evaluation
    2. 2.2 Form Factor and Stack-up Decision
    3. 2.3 Link Budget and Antenna Feature Definition
    4. 2.4 Single Antenna Element Design
    5. 2.5 Antenna Array Design
    6. 2.6 Layout Creation and Simulation
    7. 2.7 Fabrication and Design Validation
  5. 3Summary
  6. 4References

2.3 Link Budget and Antenna Feature Definition

This step converts the application requirements into numbers: the link budget shows how much antenna gain the radar needs, and the antenna features are then defined to deliver it within the form factor from Step 2.

Link Budget

The radar equation gives the received power from a target:

Equation 5. P r = P t · G t · G r · λ 2 · σ ( 4 π ) 3 · R 4 · L

Pt: transmit power at the IC output

Gt, Gr: TX and RX antenna gains

λ: freespace wavelength

σ: target radar cross-section (RCS), set by the target (person, vehicle, hand gesture, and so on.)

R: maximum detection range

L: system losses (feed lines, IC-to-antenna transition, radome, mismatch)

The detection SNR also depends on the receiver and the signal processing:

Equation 6. S N R = P r k · T · B I F · N F × p r o c e s s i n g   g a i n

Noise: thermal noise (k·T·BIF), the receiver noise figure (NF), and the IF bandwidth

Processing gain: coherent integration over range FFT samples, chirps, and virtual channels

The required SNR for a given detection probability and false-alarm rate is chosen first, and the budget is then worked backward to the antenna gain needed at the maximum range.

Antenna Feature Definition

The link budget results are combined with the Step 1 priorities to set the antenna specification:

  • Gain: Minimum gain from the link budget.
  • FOV: Azimuth and elevation coverage needed
  • Operating band and bandwidth: Must cover the full chirp sweep, with margin for fabrication and temperature shifts.
  • Impedance match: Return loss target (e.g., better than −10 dB across the band).
  • TX–RX virtual geometry: The virtual array geometry that gives the required angular resolution and unambiguous angle range.
  • TX–RX isolation: Target leakage level that does not saturate or desensitize the receiver.
  • Element and array type: Single patch for wide FOV and moderate gain, series-fed or corporate-fed arrays for higher gain and narrow FOV.
  • Polarization: Polarization is the orientation of the electric field vector of an electromagnetic wave as it propogates, observed over time at a fixed point. Types are linear, circular and elliptical. Typical patch antenna designs have linear polarization.

If the required gain and FOV cannot be met within the area and cost limits, the loop returns to Step 1 or Step 2 to relax requirements, change the form factor, or upgrade the stack-up.

A closed link budget and a complete antenna specification becomes the targets for the antenna design.

Design Example

The AWRL1422 reference board antenna design feature list based on the Step 1 evaluation and link budget calculations are given in Table 2-2

Table 2-2 Antenna Feature Requirements
Parameter Required Value
Gain > 3dB
FOV 120° × 90° at -2.5dB
Bandwidth > 3GHz
S11 <-10dB
TX-RX Virtual Geometry
TX-RX Coupling <-30dB
Element and Array Type Single Patch
Polarization Linear