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
Model
FCC ID
VERA-P173-00A
XPYVERAP174
VERA-P174-00A
XPYVERAP174
VERA-P1 series antenna reference design
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
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 1 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.
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.
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 2: Summary of antenna interface requirements
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.
Table 4: Stack-up of VERA-P1-EVK with standard FR4 substrate (εr = 4.6)
VERA-P1 antenna reference design
UBX-18022092 Page 2 of 3
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