Defense and Military RF Military RF Systems Informational

What is the difference between a search radar and a tracking radar in terms of RF design?

A search radar and a tracking radar differ fundamentally in their RF design because they serve different functions in the detection-to-engagement chain. A search radar scans a large volume of airspace to detect and locate targets, requiring a wide-area antenna beam (typically a fan beam with 1-3 degrees azimuth and 10-40 degrees elevation), moderate resolution, and high average power to achieve detection at long range against small radar cross-section targets. A tracking radar follows individual targets with high accuracy, using a narrow pencil beam (typically 1-2 degrees in both planes) and specialized angle-measurement techniques such as monopulse or conical scan to determine target position with arc-minute precision. The RF design differences extend to every subsystem: search radars typically use long pulse waveforms with pulse compression to achieve range resolution while maintaining high average power, while tracking radars use shorter pulses or CW waveforms with higher PRF for more frequent position updates. Modern multifunction phased array radars combine both search and track functions in a single aperture by time-sharing the beam between search scan patterns and dedicated track dwells on individual targets.

Category: Defense and Military RF

Updated: April 2026

Product Tie-In: Military Components, GaN Devices, Antennas

RF Design Differences Between Search and Tracking Radars

Understanding the RF design trade-offs between search and track functions is essential for radar system engineers, whether designing dedicated single-function radars or multifunction arrays that must perform both roles efficiently.

Antenna Design Differences

Search radars use fan beams that are narrow in azimuth (1-3 degrees for angular resolution and gain) but broad in elevation (10-40 degrees to cover the search volume without excessive scan time). This beam shape is created using a planar array with many columns but relatively few rows, or a parabolic reflector with a shaped feed. Tracking radars use symmetric pencil beams (1-2 degrees) with carefully controlled sidelobes below -30 dB to prevent tracking errors from nearby clutter or jammers. The tracking antenna must support monopulse operation, requiring separate sum and difference channel outputs from the antenna feed or array.

Waveform Design

Search radar: Long pulses (10-100 microseconds) with linear FM or phase-coded pulse compression to achieve range resolution of 15-150 meters while maintaining high average power. PRF is low-to-medium (100-5,000 Hz) to avoid range ambiguities over the search volume
Tracking radar: Short to medium pulses (0.1-10 microseconds) with high PRF (5,000-100,000 Hz) for frequent target position updates. Range resolution is less important than range rate (Doppler) accuracy for fire control

Signal Processing

Search radar processing emphasizes detection sensitivity (maximizing probability of detection against thermal noise and clutter) using CFAR (constant false alarm rate) detection, moving target indication (MTI), and Doppler filtering. Tracking radar processing emphasizes angle accuracy using monopulse ratio computation, range/Doppler tracking gates, and Kalman filtering for target state estimation.

Search vs Track Radar Parameters

Search radar range equation: R_max = [P_avg x G^2 x lambda^2 x sigma x T_dwell / ((4pi)^3 x k x T_s x S_min)]^(1/4)
Track accuracy (monopulse): sigma_theta ~ theta_3dB / (k_m x sqrt(2 x SNR))
where k_m = monopulse slope constant (typically 1.5-1.8)

Common Questions

Frequently Asked Questions

Can a single radar perform both search and track?

Yes. Modern multifunction phased array radars (like AN/SPY-1 Aegis or AN/SPY-6) rapidly switch their beam between search scan patterns and dedicated track dwells. The electronically steered beam can revisit each tracked target multiple times per second while continuing to scan the search volume.

Why do tracking radars use monopulse rather than sequential lobing?

Monopulse measures target angle on a single pulse by comparing simultaneous signals from two or four feed elements, making it immune to target amplitude fluctuations (scintillation). Sequential lobing techniques (conical scan) measure angle by comparing signals received at different times, making them vulnerable to amplitude modulation by the target or intentional jamming.

What is the typical angular accuracy of a tracking radar?

A well-designed monopulse tracking radar achieves angular accuracy of 0.1 to 1 milliradian (0.006 to 0.06 degrees) depending on SNR, beam width, and target characteristics. This corresponds to position accuracy of 0.1 to 1 meter at 1 km range.

Keep Reading