Part I: VNA test of antennas
We tried running VNA tests with a 8ft RG142 SMA to SMA extention cable. This gave us very, very strange results: all of our antennas looked like perfect dummy loads across astounding frequencies. We hypothesize that the cable was too lossy, and that it was attenuating the signal strength down to levels the VNA didn't see.
First calibration: 2.20 GHz to 2.45GHz (NOT SAVED)
Wifi CPA
Cable: PSU's short SMA to SMA, SMA barrel
- Design Frequency: 2.4120 GHz
- Resonant Frequency: 2.333 GHz
- Low band cutoff: 2.263 GHz
- High band cutoff: 2.385 GHz
- == Bandwidth: 122 MHz
- SWR @ Design Frequency: 1:2.70
- SWR @ Resonant Frequency: 1:1.13
SCRN00.JPG: Wifi CPA: SWR, Marker at design frequency
SCRN01.JPG: Wifi CPA: SWR, Marker at resonant frequency
SCRN02.JPG: Wifi CPA: Smith Chart, Marker at design frequency
Wifi Monopole
Cable: PSU's short SMA to SMA, SMA barrel, PSU's SMA to N
- Design Frequency: 2.4120 GHz
- Resonant Frequency: 2.275 GHz
- Low band cutoff: 2.073 GHz (OUT OF CAL)
- High band cutoff: 2.522 GHz (OUT OF CAL)
- == Bandwidth: 449 MHz
- SWR @ Design Frequency: 1:1.65
- SWR @ Resonant Frequency: 1:1.17
SCRN03.JPG: Wifi Monopole: SWR, Marker at design frequency
SCRN04.JPG: Wifi Monopole: Smith Chart, Marker at design frequency
Wifi 12-turn helix
Cable: PSU's short SMA to SMA, SMA barrel, PSU's SMA to N
- Design Frequency: 2.4120 GHz
- Resonant Frequency: Forgot to record
- Low band cutoff: Already past 1:2
- High band cutoff: Already past 1:2
- == Bandwidth: Forgot to record
- SWR @ Design Frequency: 1:2.61
- SWR @ Resonant Frequency: 1:1.82
SCRN05.JPG: Wifi 12-turn helix: SWR, Marker at design frequency
SCRN06.JPG: Wifi 12-turn helix: SWR, Marker at resonant frequency
SCRN07.JPG: Wifi 12-turn helix: Smith chart, Marker at design frequency
Wifi 10-turn helix
Cable: PSU's short SMA to SMA, SMA barrel, PSU's SMA to N
- Design Frequency: 2.4120 GHz
- Resonant Frequency: 2.374 GHz (dip closest to design frequency)
- Low band cutoff: 2.339 GHz
- High band cutoff: 2.401 GHz
- == Bandwidth: MHz
- SWR @ Design Frequency: 1:2.09
- SWR @ Resonant Frequency: 1:1.69
?SCRN00A.JPG: Wifi 10-turn helix: SWR, Marker at design frequency
?SCRN01A.JPG: Wifi 10-turn helix: SWR, Marker at resonant frequency
?SCRN02A.JPG: Wifi 10-turn helix: Smith chart, Marker at resonant frequency
SECOND calibration: 1.23 GHz to 1.27GHz (NOT SAVED)
ATV 6-turn helix
Cable: PSU's short SMA to SMA, SMA barrel, PSU's SMA to N
- Design Frequency: 1.25325 GHz
- Resonant Frequency: Too flat to measure
- Low band cutoff: Too flat to measure
- High band cutoff: Too flat to measure
- == Bandwidth: Forgot to record
- SWR @ Design Frequency: 1:1.24
- SWR @ Resonant Frequency: Too flat to measure
?SCRN03A.JPG: ATV 6-turn helix: SWR, Marker at design frequency
?SCRN04A.JPG: ATV 6-turn helix: Smith chart, Marker at design frequency
ATV 12-turn helix
Cable: PSU's short SMA to SMA, SMA barrel, PSU's SMA to N
- Design Frequency: 1.25325 GHz
- Resonant Frequency: Too flat to measure
- Low band cutoff: Too flat to measure
- High band cutoff: Too flat to measure
- == Bandwidth: MHz
- SWR @ Design Frequency: 1:1.58
- SWR @ Resonant Frequency: Too flat to measure
?SCRN05A.JPG: ATV 12-turn helix: SWR, Marker at design frequency
?SCRN06A.JPG: ATV 12-turn helix: Smith chart, Marker at resonant frequency
ATV CPA
Cable: PSU's short SMA to SMA, SMA barrel
- Design Frequency: 1.25325 GHz
- Resonant Frequency: 1.2396 GHz
- Low band cutoff: 1.232 GHz
- High band cutoff: 1.248 GHz
- == Bandwidth: 16 MHz
- SWR @ Design Frequency: 1:2.66
- SWR @ Resonant Frequency: 1:1.57
?SCRN07A.JPG: ATV CPA: SWR, Marker at design frequency
?SCRN08A.JPG: ATV CPA: Smith Chart, Marker at design frequency
THIRD calibration: 1.5 GHz to 1.6GHz (NOT SAVED)
GPS CPA
Cable: PSU's short SMA to SMA, SMA barrel
- Design Frequency: 1.57538 GHz
- Resonant Frequency: 1.5641 GHz
- Low band cutoff: 1.542 GHz
- High band cutoff: 1.589 GHz
- == Bandwidth: MHz
- SWR @ Design Frequency: 1:1.42
- SWR @ Resonant Frequency: 1:1.06
?SCRN09A.JPG: GPS CPA: SWR, Marker at design frequency
?SCRN10A.JPG: GPS CPA: Smith Chart, Marker at design frequency
Old Measurements
OLD MEASUREMENTS BELOW THIS; DO NOT USE
6-turn ATV Helix
Design Frequency: 1.25325 GHz SWR @ Design Frequency: ?? Resonant Frequency: too flat to measure Low band cutoff: too flat to measure High band cutoff: too flat to measure
SCRN03.JPG: 6-turn ATV Helix: SWR, Marker at design frequency SCRN04.JPG: 6-turn ATV Helix: Smith Chart, Marker at design frequency
12-turn ATV Helix
Design Frequency: 1.25325 GHz SWR @ Design Frequency: 1:1.31 Resonant Frequency: too flat to measure Low band cutoff: too flat to measure High band cutoff: too flat to measure
SCRN05.JPG: 12-turn ATV Helix: SWR, Marker at design frequency SCRN06.JPG: 12-turn ATV Helix: Smith Chart, Marker at design frequency
Second calibration: 1.2 GHz to 1.3 GHz (FILE01)
12-turn ATV helix looks essentially the same: flat as a board
Third calibration: 0.75 GHz to 2.5 GHz (FILE02)
12-turn ATV helix looks essentially the same: flat as a board
Fourth calibration: 2.3 GHz to 2.5 GHz (FILE03)
12-turn wifi Helix
Design Frequency: 2.4120 GHz SWR @ Design Frequency: 1:1.9 Resonant Frequency: too flat to measure Low band cutoff: too flat to measure High band cutoff: too flat to measure
SCRN07.JPG: 12-turn wifi Helix: SWR, Marker at design frequency SCRN08.JPG: 12-turn wifi Helix: Smith Chart, Marker at design frequency
10-turn wifi Helix "A"
Design Frequency: 2.4120 GHz SWR @ Design Frequency: 1:1.7 Resonant Frequency: too flat to measure Low band cutoff: too flat to measure High band cutoff: too flat to measure
?SCRN00A.JPG: 10-turn wifi Helix: SWR, Marker at design frequency ?SCRN01A.JPG: 10-turn wifi Helix: Smith Chart, Marker at design frequency
wifi Monopole
Design Frequency: 2.4120 GHz SWR @ Design Frequency: 1:1.57 Resonant Frequency: too flat to measure Low band cutoff: too flat to measure High band cutoff: too flat to measure
?SCRN02A.JPG: wifi monopole: SWR, Marker at design frequency ?SCRN03A.JPG: wifi monopole: Smith Chart, Marker at design frequency
At this point, we believe the SMA to N cable which was not part of the calibration is somehow acting like a dummy load - there's just NO WAY that the monopole is flat like that. There is some possibility that the helixes are flat.
wifi CPA
Design Frequency: 2.4120 GHz SWR @ Design Frequency: Resonant Frequency: Low band cutoff: High band cutoff:
?SCRN04A.JPG: wifi CPA: SWR, Marker at design frequency ?SCRN05A.JPG: wifi CPA: Smith Chart, Marker at design frequency
OK, now we think it's our 8ft RG142 extension cable: we hypothesize that the return signal is being attenuated so it looks like a perfect dummy load.