1. Limited Space Phased Low-Band Antennas Presented to the Twin Cities DX Association 21 March 2016, New Hope, MN Steve Fraasch, K0SF TCDXA Meeting, 21 March 20161

2. Agenda Trade-Offs: o Verticals vs. Horizontals o Driven phased vs. Parasitic Design Process Phased Examples: o 75m K0SF Phased Inv Vees o 75m K0UM Phased Inv Vees Resources Software Questions TCDXA Meeting, 21 March 20162

3. Trade Offs: 2 Element Verticals vs. Dipoles TCDXA Meeting, 21 March 20163 CharacteristicVerticalsHorizontalsComment Gain (dBi)3 to 6 depending on ground7 – 10.5 less ground independent Longer element & ground reflection enhances horizontal F/B (dB)20 Phasing network property Elevation Angle (°)8 - 20 depending on ground30 – 40 depending on heightDX advantage to low angle vertical Rx NoisePower Line Noise PronePower Line Noise ImmuneRX advantage to horizontal Tuning Easy, ground mountedCut & try w/ remote access difficult: must use softwareVector network analyzer very helpful CostLow 75m Inverted V project: ~ $150

4. Trade Offs: Driven vs. Parasitic TCDXA Meeting, 21 March 20164 CharacteristicDrivenParasiticComment Gain Arbitrary: high directivity with <.1 between elements Need correct spacing, usually.15 to.2 Elements must be spaced farther in parasitic array for directivity F/B Can achieve very high F/B and gain by proper phasing Hit or miss: can’t do much to improve without affecting gain or SWR. Phasing network property Bandwidth L’s, C’s and xmsn line stubs may crimp BW Lack of L’s & C’s helps BW Achieve 150 KHz 2:1 using network w/ multiple L’s and C’s. Relays, L’s & C’s used to change band slots. Direction Easily done in centralized enclosure Requires relay arrangement running to parasitic element to create lead/lag phase relationship. Choked control cable on ground OK for parasitic verticals, but may de-tune wire antenna. Tuning More complex, but can rely on NEC & network softwareCut & tryComputer or side cutters ? CostRequires phasing lines, L’s & C’sFew partsJunk box cuts cost

5. Network Design Process TCDXA Meeting, 21 March 20165 Choose configuration that meets requirements Assume unity feed-point currents (universally true for small n arrays) o 2 element 1/4  spaced verticals: 1a /0°, 1a /90° o 2 element.2275  inverted vees: 1a /0°, 1a /115° Set electrical phase delay: Some gain loss for very high F/B (> 25 dB) High F/B is elusive and depends on wave incidence in vertical plane Generally, 180° = Spacing° + Electrical Delay° 1/4  spacing: electrical delay = 180° - 90° = 90° 1/8 spacing: electrical delay = 180° - 45° = 135° 1/10 spacing: electrical delay = 180° - 36° = 144° Constrain the design: Feedline Length & Type Antenna Element Lengths & Diameter Spacing Phasing Run “AO” or NEC2: determine the drive impedances (or measure self & mutual impedances) Use Matlab software to design network Test

6. Network Physics TCDXA Meeting, 21 March 20166 K0UM’s Drive Z Z e = -7.94 + 42.8j Z w = 17.9 + 7.8j

7. Matlab Software: K2BT Validation TCDXA Meeting, 21 March 20167 % K2BT 2 el 1/4 wave spaced verticals, p.64, Dec ‘83 Ham Radio % zle = 21.4 - 15*1i; % zlw = 51.4 + 15*1i; % tlinc = [71.65,50]; % antparams = [3.8,36.4,1,0,zle,1,-90,zlw,1,1,-116.7042]; % nete1 = [4.0,360.25e-6]; % netw1 = [330.85e-6,1.85]; % abcd3_2ld('L:shl->serc','xmsn-theta','gain',nete1,tlinc,1,antparams,'1st',50,'2nd') % abcd3_2ld('L:shc->serl','xmsn-theta','gain',netw1,tlinc,1,antparams,'2nd',50,'2nd') % phshift(-53.2586,3.8,170.093458) % shift = [123.463e-6,5.70876]; % shift_k2bt = [125.5e-6,5.76]; % abcd3_2ld('Pi:shc->serl->shc','L:shl->serc','xmsn-theta',shift,nete1,tlinc,antparams,'1st',50,'2nd')

8. HPM 2.0 TCDXA Meeting, 21 March 20168 W1AW

9. K6STI “AO” K0UM Inv V.ant File TCDXA Meeting, 21 March 20169 K0UM 2 element Inv Vee for 75m Over Ground 3.73 MHz 14 Copper wires, feet b = 25 - 1.6686 wd = 128.5/1000/12 len = 66 sp = 10 tx = 1/12 sp1 = sp + tx sp2 = sp - tx anchor =.7071*len h =.7071*len + b 1 sp1 -anchor b sp1 -tx h wd 1 sp2 -anchor b sp2 -tx h wd 1 sp1 anchor b sp1 tx h wd 1 sp2 anchor b sp2 tx h wd 1 sp1 -tx h sp2 -tx h wd 1 sp1 tx h sp2 tx h wd 1 sp2 -tx h sp2 tx h wd 1 -sp1 -anchor b -sp1 -tx h wd 1 -sp2 -anchor b -sp2 -tx h wd 1 -sp1 anchor b -sp1 tx h wd 1 -sp2 anchor b -sp2 tx h wd 1 -sp1 -tx h -sp2 -tx h wd 1 -sp1 tx h -sp2 tx h wd 1 -sp2 -tx h -sp2 tx h wd 2 current sources Wire 7, center 1 0 Wire 14, center 1 160 Inverted Vs are twin wire spaced 2” apart to improve efficiency, (1.6 dB loss using single wires) K0SF/K0UM Height (ft) 100/70 Spacing (ft) 60/20 Phase  115/160 BW (KHz) 150/? 2:1 F l, F h (MHz) 3.60, 3.75/? Loss (dB):.13/.65 90° 20’ Apex: 70’

10. K0UM 75m Phased Inv V Azimuth Pattern TCDXA Meeting, 21 March 201610 Z e = -7.94 + 42.8j Z w = 17.9 + 7.8j

11. K0SF vs. K0UM 75m Phased Inv V Elev Pattern TCDXA Meeting, 21 March 201611 8.7/7.2 dBi @ 30  6.8/5.5 dBi @ 20  9.0/8.2 dBi @ 41  /45 

12. K0SF 75m 2 Element Phased Inverted V Example TCDXA Meeting, 21 March 201612 West 8.7a/115  East 8.7a/0  60’ spacing, 100’ height Phasing Network

13. K6STI “AO” K0SF Inverted V.ant File TCDXA Meeting, 21 March 201613 2 element Inv Vee for 75m Over Ground 3.73 MHz 4 Copper wires, feet wd = 5/64/12 ; 14 ga wire diameter len = 64;; leg length sp = 30; ; spacing from tower anchor =.866*len h = 100;; apex height b = h -.5*len;; end heights 1 sp -anchor b sp 0 h wd 1 sp anchor b sp 0 h wd 1 -sp -anchor b -sp 0 h wd 1 -sp anchor b -sp 0 h wd 2 current sources; Two current sources Wire 1, end2 1 0; 1 amp @ 0  Wire 3, end2 1 115; 1 amp @ 115  120° 60’ Apex: 100’

14. 75m Inv V Network Schematic TCDXA Meeting, 21 March 201614

15. 75m 2 Element Phased Inv V Phasing Network TCDXA Meeting, 21 March 201615 DXE 1:1 50  East 8.7a/0  West 8.7a/115  Hoffman Enclosure EBAY, $40

16. Custom Value RF Capacitor TCDXA Meeting, 21 March 201616 4ea Series x 2 Parallel 1812 SMT NPO Caps, 2.5KV from Digi-Key on scrap PCB material

17. Installation of Phasing Box & West Inverted V TCDXA Meeting, 21 March 201617

18. Problems ! TCDXA Meeting, 21 March 201618 What could possibly go wrong ??? Coupling into existing 75m radial field o Before SWR: 4:1 o Cut 4 ea 65’ counterpoise radials: 2.5:1 Bad Feedline Data from DX Engineering o DX Enging: Z o = 272 Ohms, V p =.88, Loss =.1 dB/100’ o K0SF data: Z o = 250.2 Ohms, V p =.827, Loss =.05 dB/100’ o Re-tuned Network: 1.1:1 @ 3695, then back to 4.8:1 !!! Cracked Solder Joint in Cap Array Feeding East o East takes more power, so problem more pronounced o Re-flowed solder joints -> back to 1.1:1 @ 3695 vs. 3730 KHz design freq

19. 75m & 80m DX Since Jan ‘16 & Conclusions TCDXA Meeting, 21 March 201619 Call# of callsModePower (w)SWRDirection K5P1CW5003:1West VP8SGI2CW5003:1East 7P8C1SSB15001.2:1East 3XY1T1CW1003:1East S01WS1CW1003:1East 5J0P1SSB2002.5:1East 5J0P2CW1003:1East Phased Arrays can be built & expected to work from PC simulations & analysis, even for multi L & C networks. Given balanced feedline’s very low loss, it makes for a very good phasing line if high SWR is present. The inverted vee’s high angle makes for an excellent rx ant, and still has enough gain at low angles for tx. Array tuning is sensitive to feedline characteristics. Therefore, carefully characterize your feeders.

20. Resources TCDXA Meeting, 21 March 201620 Literature:Notes "Vertical Phased Arrays," Forrest Gehrke, K2BT, Ham Radio, May '83 to May '84, Petersborough, NHzip file available Radio Antenna Engineering, Edmund Laport, McGraw-Hill, 1952, New York.pdf available Yagi Antenna Design, James L. Lawson, ARRL, 1986, Newington, CT Antenna Theory: Analysis and Design, Constantine Balanis, 3rd ed., Wiley RF Capacitors Digi-Key, Thief River Falls, MN1810, 1812 NPO EBAY Surplus Sales of Nebraska, surplussales.com Inductors AirDux Air Wound Coils, airdux.com EBAY Max Gain Systems, mgs4u.comGreat source for relays Surplus Sales of Nebraska, surplussales.com Toroid stock, Amidon, amidon.com Inductor Clips DX Engineering, dxengineering.comHard to find item Baluns, Feedline, Wire, & Insulators DX Engineering Radio City, Mounds View, MNstocks Flex Weave Wire Texas Towers, texastowers.com

21. Network Analyzer TCDXA Meeting, 21 March 201621 $350 1 & 2 port Z, SWR, Return Loss … Smith Chart & Graph.s1p data format Works remotely w/ Android Phone - Dangled from 6M Driven Element USB port: PC control & re-charge

22. Software TCDXA Meeting, 21 March 201622 NEC:Notes Antenna Optimizer, "AO" by K6STI32 bit DOS.exe available Matlab Evaluation & student versions available from Mathworks.com Full featured, non professional $149 K0SF Matlab Scripts abcd3_2ld.m: Two load phasing network design program using 3 ABCD parametersavailable abcd4_2ld.m: Two load phasing network design program using 4 ABCD parameters" abcd5_2ld.m: Two load phasing network design program using 5 ABCD parameters" match.m: Automatic network matching program" phshift.m: Determines the Pi or T network components for an arbitrary phase shifter“ optxmsn.m: Feedline parameter solver, finds Zo, Vp, & loss given open, short and load data" ttb.com: Phased array plotting program" The above require: netw.m: ABCD network formatter" swr.m: SWR & reflection cofficient calculator" phunwrap.m: Unwraps phase into -180° <  < 180°"