V-band (57-66 GHz ) Planar Antennas for WPAN Applications D. Zelenchuk, V. Fusco, G. Goussetis # ECIT Institute, Queen's University of Belfast Northern Ireland Science Park, Queen's Road, Queen's Island, Belfast, BT3 9DT, United Kingdom 1 {d.zelenchuk, v.fusco, g.goussetis}@ecit.qub.ac.uk Abstract—In this paper we present two planar V-band antennas for wireless personal area networks applications. Both of them are implemented on conventional single layer substrates that can serve as packaging for integrated transceivers. Antennas on low- and high-permittivity substrate are investigated and their performances are discussed. The antenna on low- permittivity substrate is shown to have gain higher than 10 dBi and return loss better than 10 dB in 57-66GHz frequency band. The other antenna is demonstrated to have similar characteristics only in two sub-bands of the frequency range due to poor manufacturing quality and higher order mode excitation. I. INTRODUCTION Millimeter-wave applications have recently become very attractive for consumer market. Particular attention is given to V-band unlicensed spectrum reserved for wireless personal area networks (WPAN) [1]. Up to 9 GHz is allocated between 57 GHz and 66 GHz depending on the region [2]. The bandwidth available is enough to provide more than 1 Gb/sec data rate for a short range communication, which, for example, makes possible real-time transmission of uncompressed high- definition content, mobile distributed computing, fast transfer of large files, etc. An estimation carried out elsewhere [3] states that at least 10 dBi antenna gain would be necessary to operate at 10 m distance with 20 dBm output power. Antenna technology remains crucial part of a system as it affects radio propagation channels, transceiver designs and reliability of a 60-GHz link [2]. It also has to be easily incorporated to an integrated front-end. Therefore, significant effort has been put into exploration of possible antenna solutions. Both antenna-on-chip and antenna-in-package approaches have been extensively investigated in many studies. An on-chip GaAs dipole antenna was presented in [4] and inverted-F as well as quasi-Yagi Si antennas were proposed in [5]. Both papers report that despite good return loss achieved in the frequency band of interest the gain of antenna remains low. This is a result of the low efficiency occurring from substrate loss [2] and low directivity caused by the small area of the antennas. These problems can be more effectively addressed with antenna-in-package approach as there are less constrains imposed by manufacturing process. A micro-machined air- filled horn antenna has been proposed in [6] as a part of a 60- GHz front-end, with maximum gain of 11.5 dBi and return loss better than 10 dB from 57 GHz to 63 GHz. Another micro-machined antenna integrated with a front-end receiver was reported in [7]. This was an alumina dielectric rod antenna with similar gain and well-matched from 57 GHz to 65 GHz. However, more attractive approach is to use planar configurations, which are more suitable for high-volume manufacturing. A multilayer superstrate patch antenna was investigated in [8] and a gain of 7 dBi was achieved as well as good return loss from 57 GHz to 64 GHz. A single layer LTCC grid array antenna has been developed in [9]. The antenna is well-matched from 51 GHz to 64 GHz with maximum gain of 15 dBi and minimum of 12 dBi from 57 GHz to 64 GHz. However, despite its good performance the antenna has to be vertically fed through the ground plane which implies that at least one more substrate layer is necessary for integration of active components to build a front-end unit. Brief review given above indicates that a single layer planar antenna with in-plane feed and good performance from 57 GHz to 66 GHz will provide a cost-effective and market- oriented solution for V-band WPAN front-end transceivers. In the paper we report two planar antennas which designed to ensure 10 dBi gain and return loss better than 10 dB for the specified frequency range. The antennas are manufactured using different PCB substrates that, if required, can serve as a packaging for integrated transceivers. II. ANTENNAS DESIGN The antennas presented in the paper were designed on low- permittivity (2.1) low-loss Taconic TaclamPlus substrate and high-permittivity (10.2) Rogers RO3010 substrate. The first substrate was 0.2mm thick and the second 0.254mm thick. Low profile substrates are attractive for integration of active circuitry yet significantly reduce the range of types of planar antennas from which the designer can choose in order to cover the specified frequency band. Two topologies presented in the paper simultaneously satisfy the gain and bandwidth requirement. A. Low-permittivity substrate antenna The first antenna has been designed following the wire-grid array paradigm [10]. In such arrangement thin wavelength- long microstrip lines connect half-wavelength long radiating patches. As radiating patches placed one wavelength apart they are fed in phase at the resonance. Therefore the shunt radiating resistances of the patches are combined at the