Abstract
Tunable left-handed (LH) wire antennas over a ground plane are presented in this paper. These antennas are small and have a wide tuning bandwidth and are matched to 50 Omega within the operation range. Two kinds of antennas have been developed: the monopole antenna and the half-loop antenna over ground plane. In both cases, the antennas are designed, manufactured and measured at fixed frequencies as a first step. After that, a study to replace some LH components with variable capacitors has been carried out for each antenna. Tunability over a wide bandwidth has been achieved. Finally, some prototypes of both antennas have been manufactured and measured. The tunable LH monopole antenna has been measured showing a monopolar radiation pattern with a 28% tuning bandwidth (695-924 MHz). Its radiation efficiency takes values between 50% and 70% within all the tuning bandwidth and the maximum dimension varies only between 0.11 lambda(0) at 695 MHz and 0.15 lambda(0) at 924 MHz. The tunable LH half-loop antenna over a ground plane has a radiation pattern with maximum radiation orthogonal to the ground plane. It has a 1.64:1 measured tuning bandwidth properly matched to 50 Omega (considering vertical bar s(11)vertical bar <-10 dB). Its measured radiation efficiency is always above 54% within the working bandwidth.
Original language | English |
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Pages (from-to) | 1460-1471 |
Number of pages | 12 |
Journal | IEEE Transactions on Antennas and Propagation |
Volume | 59 |
Issue number | 5 |
DOIs | |
Publication status | Published - 1 May 2011 |
Keywords
- reconfigurable antennas
- monopole antenna
- loop antenna
- tunable antennas
- Left-handed materials