What is a dielectric resonator antenna?
A dielectric resonator antenna (DRA) is a block of low-loss, moderate-to-high permittivity ceramic, typically cylindrical, rectangular or hemispherical, mounted on a ground plane and excited so that its resonant modes radiate. First investigated systematically by Long, McAllister and Shen in 1983,[1] DRAs have no conductor loss in the radiator, scale as roughly λ0/√εr, and can offer wider bandwidth than a patch of similar size at a given permittivity.[2]
How is a DRA excited?
By a coaxial probe adjacent to or inside the resonator, an aperture slot in the ground plane fed by microstrip, a microstrip line directly, or coplanar waveguide. The feed position and type select the mode: the HEM11δ mode of a cylinder radiates like a horizontal magnetic dipole, while TM01δ radiates like a monopole.[2]
What permittivity is used?
Permittivities from about 10 to 100 are typical. Higher εr shrinks the antenna but increases Q and narrows bandwidth; lower εr widens bandwidth. The aspect ratio offers a further degree of freedom that patches lack.[2]
Where are DRAs used?
Millimeter-wave antennas where conductor losses dominate, arrays, compact multiband devices and research systems. Air gaps between the resonator and ground plane shift resonance and must be controlled in manufacturing.[2]
Frequently asked questions
Is a ceramic patch a DRA?
No; a ceramic GNSS patch radiates from a metal patch on ceramic, not from dielectric modes.
Are DRAs efficient?
Low-loss ceramics give high radiation efficiency, notably at mmWave.
Why do air gaps matter?
They lower the effective permittivity and shift the resonant frequency.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “The Resonant Cylindrical Dielectric Cavity Antenna”. S. A. Long, M. W. McAllister and L. C. Shen, IEEE Transactions on Antennas and Propagation, vol. 31, no. 3, pp. 406-412. May 1983.
- “Dielectric Resonator Antenna Handbook”. A. Petosa, Artech House. 2007.