A Frequency-Selecting Technique for Mobile Handset Antennas Based on Capacitance Switching

Abstract

Abstract-This paper introduces a mobile switchable antenna for long term evolution (LTE) of the 4th generation (4G), applicable to all mobile service bands. The validity of this antenna is assessed by design, realization, and measurement. A new frequency-selecting method is used in the proposed antenna, based on capacitance switching among four states. Due to the limited antenna space in existing terminals, it is quite difficult to cover the entire low band with a single antenna. To overcome this difficulty, three singlepole double-throw (SPDT) switches, one 74HC04, and four capacitors are used. The resulting antenna covers the LTE (698-798 MHz) and GSM (824-960 MHz) bands in the low-band characteristic by realizing four capacitance states and at the same time covers the DCS (1710-1880 MHz)/PCS (1850-1990 MHz)/WCDMA (1920( -2170 bands in the high-band characteristic. The antenna provides a gain of −1.04-6.00 dBi, a radiation efficiency of 32.73-74.99%, and omnidirectional characteristics in the H-plane. Because of this outstanding performance, it is expected that the new frequencyselecting technique will be applied in 4G mobile communication terminals.

Review of recent development of minature and multi-band antennas for mobile handsets

“…To increase PIFAs' bandwidth, three techniques are proposed in recent years: (1) etching slots on the system ground plane besides [2] or underneath [3] the antenna, (2) removing part of metal out of ground at the area underneath the antenna [4,5] (The modified ground is called as notched ground and the notched region is called as no-ground region), (3) notching no-ground region on the ground and establishing impedance matching circuit at the no-ground region or at the feeding region [6][7][8][9][10].…”

“…The antenna bandwidth is improved significantly with the above techniques. Antennas covering LTE700 [5-7, 9, 10], GSM850 [2][3][4][5][6][7][8][9][10], GSM900 [2][3][4][5][6][7][8][9][10], GSM1800 [2][3][4][5][6][7][8][9][10], GSM1900 [2][3][4][5][6][7][8][9][10], UMTS [3][4][5][6][7][8][9][10], WLAN 2.4GHz [5,10], LTE2300 (2305-2400 MHz) [5,10], LTE2500 (2500-2690 MHz) [5,10] have been proposed in recent years. The shortage of these methods is that metallic electronic...…”

Multiband Handset Antenna Analysis Including Lte Band Mimo Service

“…It is well-known that achieving high isolation and low Enveloped Correlation Coefficient (ECC) between closely spaced antennas is important in portable MIMO-embedded devices where antennas must be designed within a small volume [4]. However, modern handset antennas should still be miniaturized with good performance, and isolation improvement is also important to realize the MIMO antennas for the LTE 700 bands in the limited space of recent mobile handsets [5][6][7]. Since most MIMO antenna elements of recent mobile handsets are collocated on the same printed circuit board (PCB), the surface current distribution on the PCB induces mutual coupling between antenna elements and common ground plane.…”

Carrier Aggregation Compatible Mimo Antenna for Lte Handset

“…One solution to this issue is to use smaller antennas with tunable matching circuits [4][5][6]. With frequency tuning, antenna size can be reduced as the entire frequency band of a given radio system is not covered instantaneously.…”