A new planar spiral antenna with integrated impedance transformer is presented which needs no external balun and can be fed by a coplanar waveguide. The proposed structure has a return loss of <À10 dB over a broad bandwidth of 0.5-5 GHz that is suitable for cognitive radio applications. The effects of different spiral and transformer parameters are investigated through various simulations. A case of the proposed antenna is fabricated, and measurement results are presented including return loss, gain, and radiation patterns.ABSTRACT: A novel printed microstrip reconfigurable antenna with three switchable frequencies is proposed. The proposed microstrip-fed Figure 6 Current distribution of the proposed antenna at (a) 0.7 GHz and (b) 2 GHz. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com]

No abstract

No abstract

Interest for Radio Frequency energy harvesting systems is increasing since they allow to remotely powered devices involving low power consumption, located in unreachable area or needing expensive maintenance costs. Miniaturization is also of great interest when such device needs to be embedded into mobile systems. In this paper, a compact PIFA rectenna (rectifier + antenna) was designed and evaluated for the Radio Frequency energy harvesting systems at 2.45GHz. By using a full-wave time domain technique (TLM), a global simulation is presented for designing a complete rectenna based on a RF-to-DC converter coupled to a miniature PIFA antenna. The RF-to-DC conversion efficiency of 60% is achievable over the input power range of 5-30mW. Also, a 1.9V output DC voltage could be reached when the RF power density is 1.6mW/cm 2 .

No abstract