wiki/ news/ 2004-11-08 - VNA test of LV2 CPAs and ground equipment

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

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

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

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

?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

?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

?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

?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

?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.

Part II: ATV System Long Distance (~5mi) Test