Comparative Analysis: Radar System Design - Balancing Performance, Platform, and Mission Requirements
Key Notes
AN/APG-73: Offers high versatility with integrated Synthetic Aperture Radar (SAR) and Moving Target Indication (MTI), enabling effective all-weather, multi-mission use.
Notional AAM Radar: Optimized for air-to-air engagements, emphasizing compactness, lower cost, and high tracking accuracy within a limited mission scope. [Picture not available due to that Notional means theoretical, conceptual, or hypothetical. It's an idea, not necessarily a real, existing design.]
AN/TPS-43: A ground-based, long-range radar designed for wide-area surveillance and early warning, prioritizing detection range and reliability over mobility.
Executive Summary
This paper provides a structured comparison of radar system designs across different operational contexts, focusing on how performance trade-offs are influenced by platform constraints and mission requirements. By contrasting multi-role, single-role, and ground-based systems, the analysis highlights the strategic implications of design choices for military planners and engineers. It evaluates the capabilities and design philosophies of three radar systems—AN/APG-73, Notional Air-to-Air Missile (AAM) radar, and AN/TPS-43—by examining their frequency, power, beam width, aperture, and functional attributes such as Moving Target Indication (MTI), Synthetic Aperture Radar (SAR), and Track While Scan (TWS). The AN/APG-73, an airborne multimode radar, demonstrates superior versatility with integrated SAR and MTI capabilities, making it suitable for complex, all-weather, multi-mission operations. In contrast, the Notional AAM radar is optimized for single-purpose air-to-air engagements, prioritizing compactness and cost-effectiveness. The AN/TPS-43, a ground-based system, leads in long-range detection and power output due to its large aperture, but at the cost of mobility and modern versatility. The analysis emphasizes that radar system design should be driven by mission priorities rather than optimal technical parameters, highlighting the trade-offs between sophistication, cost, platform limitations, and operational effectiveness.
Fig.1 AN/APG-73 Radar System
Fig.2 AN/TPS-43
System Specifications:
Specification Analysis
Probability of Detection (Pd) vs. Range
● Frequency: From the above table, Notional AAM and AN/APG-73 have the highest frequency. Increased atmospheric attenuation at higher frequencies may reduce Pd, especially at longer ranges or in adverse conditions.
● Power: AN/TPS-43 has the highest power. High peak and average power levels increase the radar's overall energy output, resulting in higher detection range, sensitivity, and operational performance. However, while low power consumption may be advantageous for energy efficiency and operational sustainability, it compromises the radar's ability to transmit signals over long distances and penetrate through noise and clutter.
● Pulse Repetition Frequency (PRF): Notional AAM has the highest PRF. High PRF allows for more frequent updates and tracking of fast-moving targets, enhancing the radar's ability to detect and track dynamic threats. However, high PRF can lead to range ambiguities and clutter in certain environments, potentially affecting the radar's performance in cluttered, congested scenarios or anywhere else.
● Aperture: There is no sufficient information on the aperture size of AN/TPS-43. However, according to the system description, “For ease of air shipment …two pallet loads each of less than 3400 kg…The entire equipment can be packed into two M35 trucks… light alloys are used …and micro-miniaturization techniques.” (2) An educated assumption is that the aperture of AN/TPS-43 is larger than 0.7m, which makes it the largest. Large apertures for radar systems provide improved resolution, sensitivity, and range performance but at the expense of increased size, weight, and reduced maneuverability and coverage flexibility.
● Moving Target Indication (MTI): The description of AN/APG-73 indicates a motion sensing subsystem, which is most likely to be an MTI system. Also, the 2007 report indicated it incorporated a Doppler (MTI) system. (1) A digital coherent moving target indicator system may also suggest an MTI for the AN/TPS-43. (2)
Pd vs. Range: The probability of detection is defined as the radar's ability to detect targets within its coverage area. As target distance increases, Pd may decrease due to reduced signal strength, increased clutter, and other environmental factors. To improve the Pd performance, antennas with higher gain concentrate the radar energy in the desired direction, improving sensitivity and extending the detection range. AN/TPS-43 has the largest aperture size, which can improve gain, increase power density, and reduce beam width to achieve better performance. AN/TPS-43’s narrow beam width can also provide better angular resolution and reduce the radar's susceptibility to clutter, increasing the probability of detecting small or weak targets.
Implementing clutter rejection techniques, such as moving target indication (MTI) on both AN/APG-73 and AN/TPS-43, helps filter out stationary clutter and focus on moving targets. Pd vs. Field of View (FOV)
Widening the FOV reduces the radar's ability to focus on specific areas or targets within its coverage area, potentially overlooking smaller or weaker targets. Conversely, narrowing the FOV improves Pd by concentrating the radar's resources on specific regions of interest, which may ignore the other targets. The trade-off can be avoided by implementing TWS.
● Track While Scan (TWS): The system description from the 2007 report suggests that the updated AN/APG-73 has the TWS system. (1) Based on the image of the Notional AAM, which shows a phased array radar, it's reasonable to infer the possibility of TWS capability, although specific details are not provided. The inherent attribute of phased array radars—rapid electronic beam steering—makes them highly compatible with TWS operations. Thus, it's a well-informed assumption that the Notional AAM likely includes TWS (Track-While-Scan) functionality, given that it probably utilizes a phased array antenna. However, it’s important to consider the purpose of the AAM and whether TWS is necessary in its operational context. While the AN/TPS-43 radar is an older parabola structure and lacks TWS capabilities, the AAM would need to evaluate the benefit of scanning for additional targets while routing to its primary target. In many scenarios, scanning for other targets might not be advantageous, as it could divert processing power and attention from the primary mission—hitting its designated target with precision. Therefore, while TWS functionality could be technically feasible, its actual utility would depend on the missile's operational priorities and engagement strategy. Therefore, the AN/APG-73 has the best performance.
Resolution vs. Range
Increasing resolution improves the radar's ability to distinguish between closely spaced targets.
● Beam width: Narrowing the beam width concentrates radar energy into a tighter beam, enhancing angular resolution and target discrimination. AN/TPS-43 has the lowest beam width and may lead to high resolution.
● Frequency: Higher radar frequencies offer shorter wavelengths, enabling finer resolution and improved target discrimination. AN/APG-73 and Notional AAM both have much higher frequencies than AN/TPS-43. While the frequency stays relatively the same (AN/APG-73 and Notional AAM), the bigger the aperture (AN/APG-73) leads to lower beam width, which can increase the resolution.
● Synthetic Aperture Radar (SAR): The AN/APG-73 radar contains a Synthetic Aperture Radar (SAR) system capable of producing high-resolution radar ground maps. However, its SAR functionality is likely limited in range due to its relatively small antenna size. Given its primary function in land-based operations, SAR does not apply to the AN/TPS 43. There is insufficient information to conclude whether the Notional AAM has SAR capabilities, but it is highly unlikely. SAR is a complex and specialized feature, and considering the missile's primary role—destroying an airborne target—it isn't easy to justify why it would need the ability to create ground maps while in pursuit of an aircraft. Thus, it is a reasonable assumption that the AAM would not have SAR functionality.
Overall Comparative Analysis
The AN/APG-73 and Notional AAM radar systems share similar characteristics, including the highest frequency, higher PRF, smaller aperture, lower power, and higher beam width. These similarities stem from their reliance on comparable and relatively compact platforms compared to the AN/TPS-43. The mobility requirements of airborne platforms necessitate intricate and precise designs. AN/APG-73 distinguishes itself by incorporating a Moving Target Indication system to mitigate clutter issues, thereby offering a higher Pd (R) compared to the Notional AAM. Additionally, the AN/APG-73 boasts a higher power range than the Notional AAM, further enhancing its detection capabilities. With the inclusion of TWS functionality, the AN/APG-73 can circumvent traditional Pd and FOV tradeoffs, showcasing its superior sophistication. Moreover, the AN/APG-73 integrates both SAR and MTI, enabling detailed static mapping and dynamic target tracking. This makes AN/APG-73 able to achieve both air-to-air and air-to-surface missions, while Notional AAM can only serve air-to-air. The combination of TWS capabilities and advanced tracking and recording features positions the AN/APG-73 as the most mission-capable system. Furthermore, it offers better resolution than the Notional AAM.
Conversely, the AN/TPS-43 emphasizes range capability, as demonstrated by its high power output and larger aperture. Being a land-based system, it supports a larger aperture size, which facilitates higher resolution.
IOC & Cost
The AN/APG-73 stands out as the newest design among all three, undergoing significant updates in 2007, while the AN/TPS-43 represents the oldest iteration. No information is available on the cost of the AN/TPS-43, and the AN/APG-73 is reported to cost 9.28 times more than the Notional AAM when adjusted for inflation. (1) The AN/APG-73 emerged in a more technologically advanced era than the AN/TPS-43. The complexity of the Requirement of Design (ROD) for the AN/APG-73, particularly in the context of air operations, exceeds that of the AN/TPS-43 designed for land-based use. The later design incorporating a lot more technology(sophistication) pushes the cost curve to the right. It is reasonable to assume that the AN/APG-73 incurred higher costs than the AN/TPS-43, such as the investment in design engineering for the new technologies.
The question arises as to whether the cost of the AN/APG-73 is justified by its design. It is hard to answer this question without having a combat model analysis. With limited assessment modeling here, considering its operational platform, sophistication, and mission priorities, a multi-million-dollar cost may indeed be deemed fair. Moreover, if it was the pioneering design incorporating all the desired virtues, its initial investment could pave the way for future modifications, potentially yielding exponential benefits despite the associated costs. In contrast, the Notional AAM, designed within a more constrained budget, fulfills its purpose with a simpler, single-mission approach.
Design Pattern
The AN/APG-73 radar system represents the pinnacle of sophistication, tailored for multi purpose missions with a strong emphasis on the probability of detection, resolution, and comprehensive coverage across both static and dynamic environments (SAR and MTI). There are always pros and cons of implementing certain capabilities, such as SAR requiring a predictable flight pattern to capture the static map. This can put the operator and equipment at high risk of exposure. Its high cost poses challenges for mass production despite attempts to simplify maintenance processes. Furthermore, the system's complexity necessitates a highly trained and experienced team (including operators, engineers, mechanics, and others), along with specialized manufacturing processes such as heavy machining and 3D modeling. Nevertheless, the acceptance of its cost is likely due to its critical demand from the national defense situation and pioneering status in the industry, providing significant advantages in air missions. The system's integration into aircraft further complicates industrial engineering efforts, given the stringent manufacturing requirements. Overall, as an assessment of this system, its array of capabilities outweighs this limitation. Although the range limitation could theoretically be addressed by enlarging the aperture, practical constraints related to system size (antenna), weight, and capacity make this solution unfeasible unless specifically required by mission priorities.
In contrast, the Notional AAM system shares a platform similar to the AN/APG-73 but inferior to either of the other two radars on Pd(R) and resolution. With a simpler design and lower power range, it may not be able to accommodate multi-functional capabilities and future modifications. Additionally, lacking features such as MTI suggests a single-mission orientation. However, its significant advantage lies in its potential for mass production and ease of disposal, with fewer unique manufacturing standards required.
Same as AN/APG-73, the limitation of space makes expanding the aperture not applicable. The small size of the missile severely limits the diameter of the antenna, much more so than an aircraft-based system like the APG-73, which is itself constrained by the aircraft's fuselage. Compared to larger, land-based systems such as the AN/TPS-43, the AAM's antenna is significantly smaller. This limitation typically results in a Pd(R) and poorer angular resolution due to the smaller aperture.
However, radar designers can manipulate various aspects of radar design to mitigate these limitations, though each solution often introduces its own set of trade-offs. One such adaptation is the use of a very high PRF. Increasing the PRF helps to compensate for the loss in Pd(R) caused by the small antenna, but it comes at the expense of ambiguous range resolution. For an AAM, the compromise on range resolution is less critical. The primary function of the missile's radar is not to maintain precise distance measurements but to guide the missile toward the target effectively. The need for exact range knowledge is minimal since the missile will continue its course until it engages the target, supported by a proximity detonation mechanism rather than requiring exact impact. This operational context allows the radar designer to prioritize other performance factors over range resolution, adapting the system to its specific application in air-to-air combat scenarios.
The AN/TPS-43 radar system stands apart from the other two systems primarily due to its operating platform. While still emphasizing lightweight design, it possesses the potential for further expansion through a larger aperture. This advantage allows it to excel in long-range missions with the highest Pd(R) and deliver significantly higher power output. Furthermore, expanding the aperture could enhance resolution, but it also presents challenges such as increased carrier space requirements and heightened vulnerability to enemy detection. Despite lacking the same comprehensive mapping capabilities as the AN/APG-73, this tradeoff is deemed acceptable given its distinct operational environment and slower scanning behavior. Addressing these shortcomings could involve increasing the PRF, albeit at the expense of reducing the range advantage. The optimal course of action depends on the mission's priorities and the careful consideration of the associated pros and cons.
Design Philosophy
By gathering all the aspects from the previous analysis, there are clear distinctions between the design purposes of the systems. Both AN/APG-73 and Notional AAM are suitable for close range surveillance. They may struggle in scenarios requiring long-range detection and have lower target detection. When applying the characteristics of the systems, it makes sense to implement this design for air missile purposes. Indeed, there are modifications that have been mentioned previously to improve the overall performance; there is no reason to spend extra labor and time to achieve the optimal design. For any tradeoffs, the curve can be shifted to the right by devoting more dollars. The real question is whether it serves the fundamental purpose of the mission priorities or to have a “perfect” engineering product. The answer is obviously to serve the missions at the most optimal design.
When zooming into more details, there are significant differences between AN/APG-73 and Notional AAM. The answer can be found in the cost difference and also in the add-ons. AN/APG-73 is designed as an all-weather, coherent, multimode, multi waveform, air-to-air, and air-to-surface system, while Notional AAM serves only air-to-air missions. The difference in functionalities indicates that they have different mission requirements.
Although the AN/APG-73 offers a broader range of mission capabilities compared to the AAM, the significantly lower cost of the AAM may offset this advantage. Determining the "cost effectiveness" metrics for radars necessitates a broader set of parameters and a more thorough analysis, as radars are only one component of the overall operating system. The AN/TPS-43 can be classified differently due to its fundamentally distinct carrying platform. Its capability to maintain good resolution while achieving long-range performance makes it well suited for land infrastructure and surface-to-air operations. With the highest output power among the systems discussed, it requires a significant input of energy. However, this may result in longer deployment times and mobility challenges due to the larger infrastructure. Increasing frequency is one option to enhance the resolution. It will lead to radar waves becoming more susceptible to absorption and scattering by atmospheric conditions, such as rain, fog, and atmospheric gases. This results in decreased signal propagation and range, limiting the radar's effectiveness in a long range, which defeats the initial purpose. As the tradeoff of range, it has a higher Pd than the other two systems. Expanding the aperture is another viable option to increase the antenna gains, which leads to higher Pd while others maintain the same. However, several factors must be considered: the increase in size may necessitate stronger materials or a larger support base to maintain the mechanical trust balance, and transportation challenges may arise with larger structures. Overall, the AN/TPS-43 has the most potential for mechanical design improvements. Again, any modification or reinvention needs to be performed, and an optimal design analysis needs to be performed before taking action.
Conclusion
This comparative analysis of the AN/APG-73, Notional AAM, and AN/TPS-43 radar systems highlights the complex trade-offs inherent in radar design, where performance metrics must be balanced against platform constraints, mission requirements, and cost. The AN/APG-73 emerges as the most versatile and technologically sophisticated system, capable of both air-to-air and air-to-surface missions with integrated MTI, SAR, and TWS capabilities. Its advanced features and multi-role adaptability, however, come at a higher cost and complexity. The Notional AAM, while limited in scope and functionality, fulfills its single-mission air-to-air engagement role efficiently and affordably, prioritizing simplicity and mass-produce capability. In contrast, the AN/TPS-43, a legacy land-based radar, stands out for its long-range detection and power output, benefiting from fewer platform limitations but facing challenges in mobility and modern multi-role adaptability. Ultimately, this study underscores that the “optimal” radar system is not defined by technical superiority alone but by how effectively it serves its intended mission within real-world constraints of cost, size, and operational environment.
References
Forecast International. AN/APG-73 Radar System. Accessed June 26, 2025. https://www.forecastinternational.com/archive/disp_pdf.cfm?DACH_RECNO=328.
Wolff, Christian. "AN/TPS-43." Radartutorial.eu. Accessed June 26, 2025. https://www.radartutorial.eu/19.kartei/11.ancient/karte020.en.html.
