# On the efficiency and gain of antennas

@inproceedings{Karlsson2006OnTE, title={On the efficiency and gain of antennas}, author={Anders Karlsson}, year={2006} }

The fundamental limits of the gain and efficiency of an antenna are explored. The antenna is confined in a sphere and all of the
currents are assumed to run in a material with a conductivity that is a function of the radial coordinate. The analysis is based on
the expansion of the electromagnetic fields in terms of vector spherical harmonics. Explicit expressions for the limits of gain and
efficiency are derived for different types of antennas.

## 15 Citations

Efficiency, gain and Q of antennas

- Business2007 International workshop on Antenna Technology: Small and Smart Antennas Metamaterials and Applications
- 2007

The fundamental limits of the gain, efficiency and Q-value of an antenna put severe restrictions on small antennas. In this paper it is discussed how one can avoid low efficiency and high Q-values in…

Resonance Tuning Cost in Radiation Efficiency of Electrically Small Antennas

- Physics2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting
- 2019

Numerical tools are used to predict the upper-bounds on radiation efficiency with and without a constraint on self-resonance. It is demonstrated that the assumption of lossless external tuning…

A Two-element Parasitic Antenna Approaching the Minimum Q-factor at a Given Directivity

- Business
- 2017

In this paper we investigate a super-directive antenna based on a parasitic structure with a circumscribing sphere of diameter 69 mm corresponding to 0.2$\lambda$@880 MHz. The antenna is modeled,…

Maximum Gain, Effective Area, and Directivity

- EngineeringIEEE Transactions on Antennas and Propagation
- 2019

The radiating modes of a given body are directly evaluated and analyzed here, making it possible to reduce the computational burden associated with the evaluation of electrically large structures and structures of high conductivity.

Super-directive parasitic element antenna for spatial filtering applications

- Physics2016 IEEE International Symposium on Antennas and Propagation (APSURSI)
- 2016

A super-directive parasitic element system, with a diameter of the minimum sphere circumscribing the antenna equal to 0.2λ0, is simulated and measured. A maximum directivity of 7.2 dBi is measured…

Tradeoff Between Antenna Efficiency and Q-Factor

- BusinessIEEE Transactions on Antennas and Propagation
- 2019

It is observed that small increases in Q-factor away from its lower bound allow for dramatic increases in efficiency toward its upper bound, and the tradeoff evaluation method is valid for studying arbitrary antenna geometries.

Harnessing superdirectivity in dielectric spherical multilayer antennas

- PhysicsPhysical Review B
- 2021

Small form-factor, narrowband, and highly directive antennas are of critical importance in a variety of applications spanning wireless communications, remote sensing, Raman spectroscopy, and single…

Superdirective dielectric spherical multilayer antennae

- Physics2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS)
- 2019

The stochastic optimization procedure is used to demonstrate superdirective designs of small all-dielectric antennas being spherical multilayer structure that possess the directivity that go beyond the conventional theoretical bounds for antennas smaller than the wavelength and outperform previously attained results.

Radiation Efficiency Cost of Resonance Tuning

- Computer ScienceIEEE Transactions on Antennas and Propagation
- 2018

It is demonstrated that the assumption of lossless, lumped, and external tuning skews the true nature of radiation efficiency bounds when practical material characteristics are used in the tuning network.

Correlation in MIMO Antennas

- Business
- 2020

Multiple-input multiple-output (MIMO) antennas are commonly evaluated by using the correlation coefficient. However, the correlation has several different definitions and calculation methods, and…

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