improving wearable slot antenna performance with ebg ... - Taconic

2008 Loughborough Antennas & Propagation Conference 17-18 March 2008, Loughborough, UK
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2.6 2.7 2.8 2.9 3 3.1 3.2
-5
Table 1: Measured Bandwidth and Max. Antenna
Efficiency
Return Loss (dB)
-10
-15
-20
-25
-30
-35
h 1 mm 2 mm 3 mm
Bandwidth 103 202 318
(MHz)
Max. Antenna
Efficiency
76% 73% 71%
-40
h= 1mm_S h=2mm_S h=3mm_S
h= 1mm_M h=2mm_M h=3mm_M
-45
Frequency (GHz)
Fig. 6 Measured and Simulated Return Loss at given h
The antenna efficiency is shown in Table 1. The efficiency decreases around 2-3% when h is increased
by 1 mm, this is within the quoted error (0.5dB) for the reverberation chamber. Nonetheless the
difference may be attributed to the EBG in-phase reflection feature. The slot antenna radiates a linear
polarized wave to the EBG surface, the phase difference of the reflection field from the EBG surface
to the incident E field is larger when h becomes larger, in that the antenna efficiency decreases from
76% down to 71%.
4. Conclusions
An EBG surface for improving the antenna efficiency in a wearable scenario has been proposed. We
have selected two different size EBGs to compare their performance as the target for compact
operation. By changing the proposed design h, we can discover how the centre resonant frequencies
shift and bandwidth increases. For our future work, we are improving our structure to obtain a higher
efficiency, wider bandwidth and compact design simultaneously.
Reference
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