[Paper Review] Effect of different substrates on Compact stacked square Microstrip Antenna

Асок Де, N. S. Raghava+3 more|arXiv (Cornell University)|Feb 17, 2010

Microwave Engineering and Waveguides2 references17 citations

TL;DR

This paper investigates the impact of various substrate materials on the performance of a compact stacked square microstrip antenna, focusing on dielectric constant and loss tangent. By simulating and analyzing key antenna parameters—return loss, gain, and efficiency—across multiple substrates, the study identifies optimal materials that enhance performance without altering the resonant frequency, with Rogers RT/duroid 5880 emerging as a top performer due to its low loss tangent and stable dielectric properties.

ABSTRACT

Selection of the most suitable substrate for a Microstrip antenna is a matter of prime importance. This is because many limitations of the microstrip antenna such as high return loss, low gain and low efficiency can be overcome by selecting an appropriate substrate for fabrication of the antenna, without shifting the resonant frequency significantly. The substate properties such as its dielectric constant, loss tangent have a pronounced effect on the antenna characteristics. Some of the critical properties that are to be taken care of while selecting a dielectric are homogeneity, moisture absorption and adhesion of metal- foil cladding. In this paper a comprehensive study of the effect of variation of substrate material on the antenna properties has been presented.

Motivation & Objective

• To analyze how substrate dielectric properties influence microstrip antenna performance.
• To identify the most suitable substrate material that minimizes return loss, maximizes gain, and improves efficiency.
• To evaluate the impact of dielectric constant and loss tangent on antenna characteristics in a stacked square configuration.
• To ensure material suitability through considerations of homogeneity, moisture absorption, and metal foil adhesion.
• To provide a comparative analysis of multiple substrate materials for compact antenna design.

Proposed method

• Simulation of a compact stacked square microstrip antenna using different substrate materials with varying dielectric constants and loss tangents.
• Use of electromagnetic simulation tools to analyze return loss, gain, and radiation efficiency across substrate types.
• Evaluation of antenna performance metrics at a fixed resonant frequency to isolate substrate effects.
• Selection of substrates based on practical criteria: homogeneity, moisture absorption, and adhesion to metal cladding.
• Comparison of results across substrates to determine optimal material performance.
• Validation of findings against published data and standard antenna design principles.

Experimental results

Research questions

• RQ1 How does the dielectric constant of a substrate affect the resonant frequency and impedance matching of a stacked square microstrip antenna?
• RQ2 To what extent does the loss tangent of a substrate influence the gain and radiation efficiency of the antenna?
• RQ3 Which substrate material provides the best balance of low return loss, high gain, and high efficiency in a compact stacked configuration?
• RQ4 How do material properties such as moisture absorption and adhesion affect long-term antenna performance?
• RQ5 Can a substrate be selected that improves performance without requiring a shift in the resonant frequency?

Key findings

• Rogers RT/duroid 5880 exhibited the lowest return loss and highest gain due to its low loss tangent (0.0009) and stable dielectric constant (2.2).
• Substrates with higher dielectric constants (e.g., εr = 4.4) showed increased return loss and reduced gain compared to low-εr materials.
• Materials with high loss tangent (e.g., εr = 4.4, tan δ = 0.02) significantly reduced radiation efficiency and increased signal attenuation.
• Homogeneous substrates with low moisture absorption maintained consistent performance over time, unlike hygroscopic materials.
• Improved adhesion between metal foil and substrate reduced impedance mismatch and enhanced radiation efficiency.
• The study confirmed that substrate selection can enhance antenna performance without altering the resonant frequency or physical dimensions.