Manufacturer Specs
This section contains the manufacturer specifications plus some commentary from yours truly to hopefully make it more sensical
Purchase Link: Singularity 1280 V2
TrueRC: Singularity 1280 V2
GetFPV: Singularity 1280
Polarization: LHCP or RHCP
Option to be chosen at purchase time.
Some nice visuals for circular vs linear
Antenna Theory Circular Polarization
“Circular polarization is a desirable characteristic for many antennas. Two antennas that are both circularly polarized do not suffer signal loss due to polarization mismatch. Another advantage of circular polarization is that a RHCP wave will reflect off a surface and be LHCP. This is advantageous because an antenna designed to receive RHCP waves will have some immunity to the signal-fading effects of reflected waves interfering with the desired wave. These are some of the reasons GPS signals from satellites are RHCP.”
Gain: 1.9dBic 0r 1.6 Bic
1.9Bic is from TrueRC listing, 1.6 Bic is from GetFPV listing
ic = isotropic circular
Antenna Theory Radiation Pattern
“A pattern is "isotropic" if the radiation pattern is the same in all directions. Antennas with isotropic radiation patterns don't exist in practice, but are sometimes discussed as a means of comparison with real antennas.”
This low dBic value means this antenna is nearly omnidirectional.
Cross-Polar Rejection: -15 to -30dB, (2.2%)
Axial Ratio: 1.0
“A circularly polarized field is made up of two orthogonal E-field components of equal amplitude (and 90 degrees out of phase). Because the components are equal magnitude, the axial ratio is 1 (or 0 dB).”
Bandwidth: 1250MHz-1290MHz
Radiation Efficiency: 99%
SWR: <=1.5:1
Weight: 15g
Dimensions(head): 40.5mm dia. X 22.5mm height.
The antenna cannot be a cloverleaf antenna
this is because it is too small
40.5mm diameter
~1270 MHz
Length: xxmm
Cable: RG402/RG316 coax.
Connector: True-SMA .
This is a normal SMA connector, they just want to be fancy
Patent: US. Pat. 10,804,618 ‘
https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/10804618
This gives information about what type of antenna this really is!
Mounting Requirements:
Do not paint antenna
Do not mount close to conductors
Feed line can mechanically be ignored (no electrical requirements for the feed line)
Try to maximize time the airside antenna has line of sight to the groundside antenna for common aircraft attitudes
SWR can be measured with a VNA after mounting
Project Pegasus Use
Project Pegasus uses this component as documented in 2024 System Architecture for our 1.3 ghz video transmission system. This antenna will go on the airside connected to a transmitter either Foxeer 5 W VTX or Mateksys 800mW VTX . On the groundside this antenna could be connected to the RMRC VRX + Tuner as a part of the video tower system, however, in my engineering opinion the TrueRC X-AIR 1.3 is the preferable antenna here with the only drawback being size. The SWR of the TrueRC X-AIR 1.3 is not published however I [Daniel] measured it to be below 1.3:1 in the bandwidth of 1250MHz-1290MHz in our prototype tracking antenna setup with a NANOVNAH4 in Sept 2023.
Internal Testing
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External Resources:
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