Folded planar inverted‐F antenna (PIFA) with two via holes for bandwidth enhancement

Abstract

signed RLC network will bring side effects, i.e., a worse S 22 around the cut-off frequency, as shown in Figure 6. A trade-off in design should be made between a wider bandwidth and a decent stability.To further demonstrate the amplifier bandwidth improvement from series RLC network, a common-emitter amplifier and a common-collector followed by a common-emitter amplifier are designed for a complete comparison. The measured S 21 parameters are plotted in Figure 7. For the sake of fair comparison, all amplifiers are biased at the same collector current. Input and output ports are terminated with 50 ⍀. From Figure 7, a much wider bandwidth is achieved in amplifier with the RLC network. CONCLUSIONSA bandwidth improvement network incorporated with a gain compensation technique is proposed for HBT amplifiers. The network consists of a small value of inductor at base of Q3, in series with a decoupling capacitance and a resistance to improve high frequency stability. The network cannot only be implemented in a common-collector following by a cascode amplifier, but also in a traveling wave matching (TWM) amplifier, a distributed amplifier (DA), and a matrix amplifier (MA) [5][6][7][8][9]. The network has been demonstrated to improve the bandwidths of various amplifiers.

Compact size planar folded pifa design for mobile handset

“…With such a design, enough coupling capacitances are formed to cancel the inductive reactance induced by the feed line, therefore enhancing the impedance bandwidth of the three excited operating frequencies [14]. Furthermore, rather than using the coupling technique to feed the radiating element [12,14], a more direct approach is used by using via hole to provide an electrical connection between the feed line and the folded radiating element [15]. Details of the proposed antenna design and both theoretical and experimental results are presented and discussed.…”