Radiofrequency (RF) engineers, anyone interested in high field RF coils.A radiative antenna has been proposed to address more uniform B1+ and B1- patterns than currently available loop array coils at Ultra High Field (UHF) [1]. When applied for imaging the whole brain, however, a limited z-directional coverage of the original Monopole Antenna Array (MA) coil caused degradation in the transmit and receive performance in the inferior areas of the brain [2]. Fig. 1. Picture of SEMAS coil. The upper corners of the ground plate were cut to prevent a direct contact of the MRI bore. In this work, we explored a new design of the transceiver monopole antenna coil. We modified monopole antenna array coil to a spiral type [3]. This coil, which we refer to as an Spiral Extended Monopole antenna Array with individual Shield (SEMAS) coil, has an increased length of monopole antennas with shields. To demonstrate the advantage of this newly designed coil, the performance was compared to the MA coil as well as the Spiral Monopole antenna Array (SMA) coil [3,4].The photos of new coils are shown in Fig. 1. Each coil has eight equally spaced monopole antennas, and each antenna is connected to a coaxial cable via a ground plate at one end. The copper ground on acrylic plate (size of plate: 36 x 36 cm2) was divided into 21 pieces (size of each piece: 5 x 12 cm2) to reduce eddy current. The divided ground plates were connected to ceramic capacitors (330 pF). In the original MA coil, the length of an monopole antenna was adjusted to 20 cm (SMA: 14.1 cm, SEMAS: 20 cm through the z-direction) In the SEMAS coil, copper shields (size of shield: 2 x 28.3 cm2) were placed on both sides of the monopole antenna. The shields were spaced 1 cm away from the monopole antenna. The distance between the feeding point of the monopole antenna and the shield was 2 cm. Fig. 2. (a) Measured flip angle maps (in degrees) and (b) receive sensitivity maps (in arbitrary units) in the sagittal, coronal and axial planes. The images are from mid-sagittal, mid-coronal and a lower axial planes. The number represents a quantitative measure at an ROI (3 x 3 cm2) All imaging experiments were performed on a 7T MRI scanner (Siemens Medical Solutions, Erlangen, Germany). A custom-designed interface box with an eight-channel power divider was utilized to distribute the transmit signal to each coil equally. To compare the flip angle distribution among the three coils, actual flip angle imaging (AFI) pulse sequence (TR1 / TR2 = 20/100 ms and TE = 3.1 ms, bandwidth = 330 Hz/pixel) was acquired. To investigate the SNR of each coil, proton density-weighted images (TR = 1000 ms, TE = 2.5 ms,) were obtained for the sagittal, coronal and axial planes. The reference voltage of MA, SMA and SEMAS for imaging was 240 V. Fig. 2 shows the measured flip angle maps (Fig. 2a) and the receive sensitivity maps (Fig. 2b) of the MA, SMA and SEMAS acquired by experiment in sagittal, coronal and axial view, respectively. All of quantification of specific ROI’s in the sagittal view is marked in Fig. 2. The receive sensitivity (Fig. 2b) in the three coils are no significant differences through the z-direction. The maximum standard deviation difference of the same ROIs among the three coils was shown at the occipital lobe. However the measured flip angle of the SEMAS coil are substantially higher compared to the MA and the SMA coils. The SEMAS coil shows larger mean flip angles values than the other two coils (SEMAS: 16˚, MA: 8˚, SMA: 11˚). And the standard deviation of the measured flip angle was significantly different among three coils (SEMAS: 9, MA: 25, SMA: 19). A similar observation can be seen in the coronal and axial plane at measured flip angle maps where the SEMAS coil shows larger flip angles than the other coils.In this study, we have demonstrated that the newly designed monopole antenna coil, SEMAS, improves B1+ field uniformity in the whole brain and it efficiently penetrates into the deep brain when compared with the MA and SMA coils. The improvement was particularly significant in the inferior part of the brain where the brainstem and the cerebellum are located. Hence, the new coil may potentially be used for clinical and scientific applications at UHF (≥ 7T) that require a wide spatial coverage including the brainstem and cerebellum areas.