wiki/ news/ 2004-07-22 - VNA test of solid UHMW PE "v2b" CPAs

Overview

Glenn and Andrew tested the v2b cylindrical patch antennas on the HP VNA in the PSU microwave lab. The v2b CPA's have 1/16" UHMW PE as a dielectric. We purchased "tape", which has acrylic adhesive on one side, and then proceeded to "spark gap" (oxidize with ozone) the other side and then used 2m super 77 acrylic adhesive spray to make the other side sticky.

Note that the huge jump from Er = ~1.4 of the foam to the Er = ~2.3 of the solid PE makes a huge difference in the feed structure - they should be way, way off. But all we cared about for these tests were the resonant frequency of the antenna, to make sure there wasn't something terribly wrong with our idea.

CONCLUSION: Our predicted resonant frequencies were shockingly close to our measured, especially given the off-frequency nature of the corporate feeds. we took this to be a good sign. The antennas were also pretty robust to flexing and what not, although that did change their frequency by 0.1 - 5 MHz. Hooray.

NEXT TIME DON'T FORGET: FLOPPY, BARREL, PATCH CORD


WIFI Antenna

Predicted center frequency: 1.714 GHz

FILE00 = 1.5 TO 2.0 CALIBRATION

"Wifi" antenna:  F = 1.6837 GHz, SWR = 1.02:1, BW = 1.6596 GHz - 1.7093 GHz = 49.7 MHz

SCRN01 = resonant frequ.
SCRN02 = smith

We futzed with the antenna, and got f = 1.6839 GHz

on it's side, no zip tie, opened up: f = 1.6879 GHz
on it's side, no zip tie, hands in holding cylindrical: f = 1.6843 GHz

Decided to try calling in a narrower range just to make sure the wide range wasn't affecting our results.

FILE01 - 1.575 to 1.80 CALIBRATION

SCRN03 = resonant freq. on it's side, no zip tie, hands inside holding cylindirical.

on it's side, no zip tie, opened up: f = 1.6911 GHz
on it's side, no zip tie, hands in holding cylindrical: f = 1.6864 GHz
SCRN01.JPG
SCRN01 = Wifi angtenna resonant frequency

SCRN02.JPG
SCRN02 = Wifi angtenna smith chart

SCRN03.JPG
SCRN03 = Wifi angtenna resonant freq. on it's side, no zip tie, hands inside holding cylindirical.

GPS

Predicted center frequency: 1.114 GHz

FILE02 = 1.0 TO 1.2 CALIBRATION

Antenna on side, slot down, hands holding cylindrically on the inside.

SCRN04 = resonant frequ.
SCRN05 = smith

F = 1.1025 GHz, SWR = 1.02:1, BW = 1.0826 GHz - 1.1137 = 31.1 MHz
SCRN04.JPG
SCRN04 = GPS antennna resonant frequency

SCRN05.JPG
SCRN05 = GPS antennna smith chart


ATV

Time: 10:49am - swapped out disks, numbering scheme back to zero

Predicted center frequency: 0.903 GHz

FILE00A = 0.8 TO 1.0 CALIBRATION

Antenna on side, slot down, hands holding cylindrically on the inside.

SCRN00A = resonant frequ.
SCRN01A = smith

F = 0.90005 GHz, SWR = 1.15:1, BW = 0.8925 GHz - 0.9076 GHz = 15.1 MHz
SCRN00a.JPG
SCRN00a = ATV antenna resonant frequency

SCRN01a.JPG
SCRN01a = ATV antenna smith chart


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