[eagle] Re: Phased Array Concepts

John B. Stephensen kd6ozh at comcast.net
Tue Oct 9 08:38:04 PDT 2007


Would an inductor in series with each varactor help? The total reactance can 
then vary from a positive value, through zero to a negative value so that a 
greater phase variation might be acheived with lower reflections.

73,

John
KD6OZH

----- Original Message ----- 
From: "Matt Ettus" <matt at ettus.com>
To: <K3IO at verizon.net>
Cc: "AMSAT Eagle" <Eagle at amsat.org>; "'Brian E. Gaffney'" 
<beg at bellatlantic.net>; "Daniel Schultz" <n8fgv at usa.net>
Sent: Sunday, October 07, 2007 06:47 UTC
Subject: [eagle] Re: Phased Array Concepts


>
>
> Tom,
>
> I have the working simulation of the tapped delay line design.   I did
> all my sims with a delay line spacing of 30mm per element, or 0.3
> wavelengths at 300 MHz.  Some observations:
>
> - Once the varactor capacitance gets high enough, you start to get
> reflections which mess up the phasing.  It happens to the elements
> nearest to the generator (center of the array) first.  At 300 MHz, you
> get bad behavior at the center, first, and second elements if the
> capacitance gets over about 0.8 pF.  Going to a lower frequency will
> allow for more capacitance, but you will need longer delay lines, and
> will then end up with the same problem.
>
> - The tap for getting the signal out may add capacitance of about the
> same order of magnitude.
>
> - The delay line needs to be long enough, or the caps all look like they
> are in parallel.
>
> - The center element will be common to all 12 strings, so some method of
> splitting is necessary.  This splitting will introduce a phase offset
> which is not linear with the applied voltage, so it will need to be
> compensated for by changing the length of the delay lines between the
> center element and the first varactor.
>
> - You can probably reduce the reflections by putting attenuators in the
> delay lines, but these would make the DC biasing of the varactors more
> difficult.
>
> I have attached my simulation.  It was done in qucs, which runs on
> linux.  See qucs.sf.net or get it from your distribution.
>
> Matt
>
>
> Tom Clark, K3IO wrote:
>> I have (finally!) put the finishing touches on my magnum opus describing
>> my ideas on phased arrays and shipped it off to be included in the
>> Pittsburgh symposium proceedings. If you want to see it, it is available
>> for viewing at
>> http://mysite.verizon.net/w3iwi/electronic_scanning_antennas.pdf. This
>> version has some figures in color, but the proceedings is in B&W (this
>> format is available if you need it).
>>
>> This took me a lot longer than I anticipated. I had a couple of fairly
>> major Gates-induced computer failures, some of which still plague me
>> (like I'm using my notebook for all Email). I advise against the use of
>> Office 2007.
>>
>> I am hoping that this week I will have time to test Dan's hardware so I
>> can have some results to report by Pittsburgh.
>>
>> Matt -- this has the numbers I was trying to remember last weekend.
>>
>> For all -- your comments and critiques are solicited.
>>
>> 73, Tom
>>
>>
>>
>
>


--------------------------------------------------------------------------------


> <Qucs Schematic 0.0.12>
> <Properties>
>  <View=40,-14,1338,912,0.9689,0,87>
>  <Grid=10,10,1>
>  <DataSet=simple_phaser.dat>
>  <DataDisplay=simple_phaser.dpl>
>  <OpenDisplay=0>
>  <showFrame=0>
>  <FrameText0=Title>
>  <FrameText1=Drawn By:>
>  <FrameText2=Date:>
>  <FrameText3=Revision:>
> </Properties>
> <Symbol>
> </Symbol>
> <Components>
>  <TLIN Line4 1 650 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <GND * 1 110 250 0 0 0 0>
>  <Pac P1 1 110 180 18 -26 0 1 "1" 1 "50 Ohm" 1 "0 dBm" 0 "1 GHz" 0 "26.85" 
> 0>
>  <TLIN Line5 1 220 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <TLIN Line1 1 330 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <TLIN Line2 1 440 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <TLIN Line3 1 550 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <GND * 1 930 240 0 0 0 0>
>  <Pac P2 1 930 170 18 -26 0 1 "2" 1 "50 Ohm" 1 "0 W" 0 "1 GHz" 0 "26.85" 
> 0>
>  <TLIN Line6 1 750 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <TLIN Line7 1 850 110 -26 20 0 0 "50 Ohm" 1 "30 mm" 1 "0 dB" 0 "26.85" 0>
>  <.AC AC1 1 100 310 0 49 0 0 "lin" 1 "0.2 GHz" 1 "0.4 GHz" 1 "100" 1 "no" 
> 0>
>  <GND * 1 280 270 0 0 0 0>
>  <GND * 1 390 270 0 0 0 0>
>  <GND * 1 500 270 0 0 0 0>
>  <GND * 1 600 270 0 0 0 0>
>  <GND * 1 700 270 0 0 0 0>
>  <GND * 1 800 270 0 0 0 0>
>  <.SW SW1 1 90 520 0 83 0 0 "AC1" 1 "lin" 1 "C1" 1 "0pF" 1 "2pF" 1 "5" 1>
>  <C C1 1 280 220 17 -26 0 1 "C1" 1 "" 0 "neutral" 0>
>  <C C2 1 390 220 17 -26 0 1 "C1" 1 "" 0 "neutral" 0>
>  <C C3 1 500 220 17 -26 0 1 "C1" 1 "" 0 "neutral" 0>
>  <C C4 1 600 220 17 -26 0 1 "C1" 1 "" 0 "neutral" 0>
>  <C C5 1 700 220 17 -26 0 1 "C1" 1 "" 0 "neutral" 0>
>  <C C6 1 800 220 17 -26 0 1 "C1" 1 "" 0 "neutral" 0>
>  <Eqn Eqn1 1 330 320 -32 19 0 0 "phase_p1=angle(p1.v)" 1 
> "phase_p2=angle(p2.v)" 1 "phase_p3=angle(p3.v)" 1 "phase_p4=angle(p4.v)" 1 
> "phase_p5=angle(p5.v)" 1 "phase_p6=angle(p6.v)" 1 "phase_p7=angle(p7.v)" 1 
> "yes" 0>
>  <.SP SP1 0 530 310 0 83 0 0 "lin" 1 "0.1 GHz" 1 "0.4 GHz" 1 "100" 1 "no" 
> 0 "1" 0 "2" 0 "no" 0 "no" 0>
>  <.SW SW2 0 530 530 0 83 0 0 "SP1" 1 "lin" 1 "C1" 1 "0.5pF" 1 "3pF" 1 "4" 
> 1>
>  <Eqn Eqn2 0 330 570 -32 19 0 0 "s11_db=dB(S[1,1])" 1 "s22_db=dB(S[2,2])" 
> 1 "yes" 0>
> </Components>
> <Wires>
>  <110 210 110 250 "" 0 0 0 "">
>  <110 110 110 150 "" 0 0 0 "">
>  <110 110 190 110 "p1" 170 60 18 "">
>  <250 110 280 110 "p2" 280 60 0 "">
>  <360 110 390 110 "" 0 0 0 "">
>  <580 110 600 110 "" 0 0 0 "">
>  <470 110 500 110 "" 0 0 0 "">
>  <930 200 930 240 "" 0 0 0 "">
>  <680 110 700 110 "p6" 710 60 9 "">
>  <780 110 800 110 "p7" 830 60 17 "">
>  <880 110 930 110 "" 0 0 0 "">
>  <930 110 930 140 "" 0 0 0 "">
>  <280 250 280 270 "" 0 0 0 "">
>  <280 110 300 110 "" 0 0 0 "">
>  <280 110 280 190 "" 0 0 0 "">
>  <390 250 390 270 "" 0 0 0 "">
>  <390 110 410 110 "p3" 440 50 20 "">
>  <390 110 390 190 "" 0 0 0 "">
>  <500 250 500 270 "" 0 0 0 "">
>  <500 110 520 110 "p4" 540 60 15 "">
>  <500 110 500 190 "" 0 0 0 "">
>  <600 250 600 270 "" 0 0 0 "">
>  <600 110 620 110 "p5" 640 60 5 "">
>  <600 110 600 190 "" 0 0 0 "">
>  <700 250 700 270 "" 0 0 0 "">
>  <700 110 720 110 "" 0 0 0 "">
>  <700 110 700 190 "" 0 0 0 "">
>  <800 250 800 270 "" 0 0 0 "">
>  <800 110 820 110 "" 0 0 0 "">
>  <800 110 800 190 "" 0 0 0 "">
> </Wires>
> <Diagrams>
>  <Rect 670 780 240 160 3 #c0c0c0 1 00 1 0 0.2 1 1 -0.1 0.5 1.1 1 -0.1 0.5 
> 1.1 315 0 225 "" "" "">
> <"s11_db" #0000ff 0 3 0 0 0>
> <"s22_db" #ff0000 0 3 0 0 0>
>  </Rect>
>  <Rect 980 646 301 326 3 #c0c0c0 1 00 1 2e+08 5e+07 4e+08 1 -2.34563 0.5 
> 0.5 1 -1 0.5 1 315 0 225 "" "" "">
> <"phase_p1" #0000ff 0 3 0 0 0>
> <"phase_p2" #ff0000 0 3 0 0 0>
> <"phase_p3" #ff00ff 0 3 0 0 0>
> <"phase_p4" #00ff00 0 3 0 0 0>
> <"phase_p5" #00ffff 0 3 0 0 0>
> <"phase_p6" #ff5500 0 3 0 0 0>
> <"phase_p7" #000000 0 3 0 0 0>
>  </Rect>
> </Diagrams>
> <Paintings>
> </Paintings>
>


--------------------------------------------------------------------------------


> _______________________________________________
> Via the Eagle mailing list courtesy of AMSAT-NA
> Eagle at amsat.org
> http://amsat.org/mailman/listinfo/eagle
> 



More information about the Eagle mailing list