Low profile double resonance frequency tunable antenna using RF MEMS variable capacitor for digital terrestrial broadcasting reception

Abstract

It is difficult to realize the built-in antenna for wideband systems, because a frequency bandwidth of the low profile antenna is narrow. A frequency tunable antenna is a technique for wideband characteristics. In this paper a low profile double resonance frequency tunable antenna using MEMS variable capacitors is presented. It has high efficiency over a wide frequency band. Through both resonant portions from 465 to 665 MHz, the efficiency of more than -4 dB and the VSWR of less than 3 are observed in the measurement using the variable capacitor of 0.4-0.9 pF.

Antenna Miniaturization with MEMS Tunable Capacitors: Techniques and Trade-Offs

“…In the case of antennas based on wideband coupling elements, the tuner is typically placed at the feed to match the antenna to different operating frequencies simultaneously [6,[19][20][21] or instantaneously [22][23][24][25]. Frequency reconfigurability can also be achieved by loading the antenna structure itself [26][27][28] or by placing the tuner between the antenna element and the ground plane [29][30][31][32][33][34][35]. The latter is the most common use of tunable MEMS capacitors; therefore, this placement will be used for the following investigation.…”

Tuning Range Optimization of a Planar Inverted F Antenna for the LTE Low Frequency Bands

“…When the value of the capacitor becomes larger, the operation frequency becomes lower and the efficiency degrades, because the power consumption in the parasitic resistance of the capacitor has become larger due to the increase of the current in the capacitor [14].…”

Thermal loss becomes an issue for narrow‐band tunable antennas in fourth generation handsets

“…Frequency reconfigurability can be achieved with the integration of switches, variable capacitors, phase shifters or tunable substrates in the antenna structure. Most commonly, FRAs use PIN diodes [3, 4], varactor diodes [5, 6], micro‐electro‐mechanical systems (MEMS) switches [7, 8] or MEMS tunable capacitors [9–11]. As detailed in [12], switched capacitors – for example, field effect transistors – lead to an intrinsically low breakdown voltage and power handling, thus limiting its application for 4G handsets [13].…”

“…Frequency-reconfigurability can be achieved with the integration of switches, variable capacitors, phase shifters or tunable substrates in the antenna structure. Most commonly, FRA's use PIN diodes [3,4], varactor diodes [5,6], Micro-Electro-Mechanical Systems (MEMS) switches [7,8], or MEMS tunable capacitors [9][10][11]. As detailed in [12], switched capacitors -e.g.…”