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Joined: Thu, Mar 27th 2014, 10:48 Roles: N/A Moderates: N/A

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2 meter slot-cube antenna KC5EZC on 30/3/19
Using AL foil works because it's emicivity is different than copper.
A copper sheet only changes the diameter of the tube.

I am making a new version with 0.050 " added to vertical members of the cube.
I tried to add C to tuning but even with a gymic (twisted pair of insulated wire) was too much C.
3rd thing is to use an open stub and see what the smith chart looks like.
2 meter slot-cube antenna KC5EZC on 3/2/19
I was able to tuen the 2 meter slot antenna to 147.5 by using aluminum foil wrapped around axially around two legs of top and bottom loop. Improved my reception of Xenia repeater.
We did a scan using a Rig Expert and we were not able to find any harmonic resonances. The sweep was from 56 Mhz to almost 500 Mhz and the only resonate point we found was @ 147.5 with foil attached.
Next wee we are going to try a couple of large Ferrite split beads so we can manually tune it in the 2 m Amature band.
Whit no foil it tuned in the center of 2 meter marine band !
More next week.
2 Meter Slot-Cube Antenna (QST Jan 2019) K1AWC on 21/1/19
Completed project last month.
Using a MFJ analyzer I got the antenna to tune @ 151.5 MHz.
Using HP Oscillator & 250 Mhz Tecktronix scope the antenna radiated pretty well at 146.5. Have not calibrated analyzer but suspect it may be off frequency.
Plan to visit DARA clubhouse and we will use a better analyzer and then we will know.
I will publish results of test.
2 meter slot-cube antenna KC5EZC on 20/1/19
More:
Is the antenna scalable?
Would like to make one for 70 cm.
Would like to make one for 800 mHz for cell modem.
2 meter slot-cube antenna KC5EZC on 20/1/19
Built 2m slot and it worked.
Using MFJ antenna analyzer it tuned @ 151.5 MHz.
Going to try to tune it to 146.5 if I can. Suggestions were to use Alum foil around some legs. RF impedance of ALUM and Copper are different I am told.
As it exists it has a lot of gain over the rubber antenna, Radio gets out better even though the SWR is about 1.5.
I am also suspecting the Antenna Analyzer is off freq. too.

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