u blox VERAP174 Host-based V2X transceiver module User Manual Antenna trace layout

u-blox AG Host-based V2X transceiver module Antenna trace layout

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Antenna trace layout

VERA-P1 antenna reference design UBX-18022092 Page 1 of 3 VERA-P1 series antenna reference design Topic : VERA-P1 antenna reference design Doc.No: UBX-18022092 Revision R01 Date: Name Signature Created 09-Nov-2017 Stefan May smay Checked Released 04-Jun-2018 Daniel Dietterle ddie We reserve all rights in this document and in the information contained therein. Reproduction, use or disclosure to third parties without express authority is strictly forbidden. © 2018 u-blox AG 1 Scope This document defines the essential specifications necessary to implement the VERA-P173 / VERA-P174 antenna reference designs. The information contained herein and its references should be sufficient to guide a skilled person in an attempt to implement the design on a host carrier. It will provide the designer with PCB layout details and expected performance specifications. The document supports a connector-based designs for the use of external antennas (one for each antenna pin of the module). 2 FCC ID reference Model FCC ID VERA-P173-00A XPYVERAP174 VERA-P174-00A XPYVERAP174 Table 1: FCC IDs for different models of VERA-P1 series modules 3 General description and requirements The antenna reference design provides two RF interfaces for connecting the external antennas. Antenna ports ANT1 and ANT2 have a nominal characteristic impedance of 50  and must be connected to the related antenna through a 50  transmission line to allow proper impedance matching along the RF path; a bad termination of the pin may result in poor performance or even damage to the RF section of the module. For optimal antenna performance in multi-radio mode, the isolation between the antennas must be maximized; the designer must follow the requirements specified in Table 2 and Table 3 to ensure good performance.
VERA-P1 antenna reference design UBX-18022092 Page 2 of 3 Item Requirements Remarks Impedance 50  nominal characteristic impedance The impedance of the antenna RF connection must match the 50  impedance of the ANTx pin. Frequency Range 5850 - 5925 MHz For 802.11p. Return Loss S11 < -13 dB (VSWR < 1.5:1) Abs. Max. The return loss or the S11, as the VSWR, refers to the amount of reflected power, measuring how well the primary antenna RF connection matches the 50  characteristic impedance of the ANTx pin. The impedance of the antenna termination must match as much as possible the 50  nominal impedance of the ANTx pin over the operating frequency range thus, maximizing the amount of the power transferred to the antenna. Efficiency > -1.5 dB ( > 70% ) recommended > -3.0 dB ( > 50% ) acceptable The radiation efficiency is the ratio of the radiated power to the power delivered to the antenna input. The efficiency is a measure of how well an antenna receives or transmits. Table 2: Summary of antenna interface requirements Item Requirements Remarks Isolation (in-band) |S21| > 50 dB recommended |S21| > 43 dB minimum The antenna to antenna isolation is the loss between the primary and the secondary antenna; high isolation results from low coupled antennas. Isolation (out-of-band) |S21| > 35 dB recommended |S21| > 30 dB acceptable Out-of-band isolation is evaluated in the band of the aggressor to ensure that the transmitting signal from the other radio is sufficiently attenuated by the receiving antenna to avoid saturation and intermodulation effects at the receiver’s port. Table 3: Summary of antenna isolation requirements 4 Reference design of RF path The reference design of the 50 Ω path to connect the modules antenna pins with a SMA connector is displayed in Figure 1 and the dimensions concerning the board stack-up (Table 4) are specified in Table 5. An SMA connector is used to mount the antenna from Table 6. PCB Layer Material Thickness Solder mask top General LPI solder mask 20 µm Top Copper Foil 35 µm Dielectric Pre-preg 600 µm L2 Copper Foil 35 µm Dielectric Core 240 µm L3 Copper Foil 35 µm Dielectric Pre-preg 600 µm Bottom Copper Foil 35 µm Solder mask bottom Generic LPI Soldermask 20 µm Table 4: Stack-up of VERA-P1-EVK with standard FR4 substrate (εr = 4.6)
VERA-P1 antenna reference design UBX-18022092 Page 3 of 3 Figure 1: Coplanar waveguide with ground dimension specification Item Value S 400 µm W 900 µm T 35 µm H 600 µm Spacing between ANT1 and ANT2 waveguides 16 mm Table 5: Coplanar waveguide with ground specification 5 Antenna The module has been approved for use with any dipole antenna with less or equal to 6 dBi peak gain. An example of an approved antenna is listed in Table 6. Model name Manufacturer and description Gain [dBi] (peak) TD.10.5113 Taoglas, Dipole Terminal Antenna SMA Connector 5.88 dBi Table 6: Approved antenna example

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