Isolation of high-Q antennas for mobile handsets

High-Q antennas with built-in coils: For mobile devices

“…The antennas with discrete coils [4], shown in Figure 1, exhibits an isolation of better than -22 dB at 700 MHz. From the measured efficiency plot of the mock-up, depicted in Figure 2, it is seen that the peak efficiencies of the Tx and Rx antennas are -4.7 dB and -5.1 dB, respectively.…”

“…Since the integrated coils have air core, their Quality factor (Q) are expected to be much better compared to the discrete ones. Only three turns are used on each side of the Printed Circuit Board (PCB) to keep the 3.5 mm antenna height and similar antenna Q as in [4]. Therefore, it becomes necessary to position the antenna arms at both sides of the PCB (see Figure 3b) in order to force the antenna to the desired resonance frequency (Tx: 689-716 MHz, Rx: 728-746 MHz).…”

Mutual coupling investigation between loop and two inverted‐L antennas operating below 1 GHz

“…Mutual coupling between the antennas is not directly related to the correlation, but it has a large role in determining it [4, 5]. Narrow‐band antennas have the advantage of being able to provide low coupling between the Tx and Rx antennas, even below 1 GHz [6]. However, for operation in MIMO mode a second Rx antenna is also needed, making it quite challenging to achieve low coupling between all three antennas.…”

Isolation between three antennas at 700 MHz: for handheld terminals

“…High antenna coupling often leads to high correlation in the branches of the multiple-input multiple-output (MIMO) receiver. Owing to the frequency offset and narrow-band characteristic, good isolation is achievable between the Tx and Rx antennas at 700 MHz [5]. However, a diversity Rx (Dx) antenna is needed for MIMO performance.…”