I've been modeling a Hi-VHF and UHF combo antenna based on a design the Yurii posted on his site. I've always got 1/2" copper scraps, so I designed around 1/2" copper plumbing pipe and joints. Gain looks pretty good in both Hi-VHF and UHF bands. SWR and impedance look OK in UHF, but are a bit high in Hi-vhf. I posted it, just to see what others think, and see if anyone has ideas to improve it. This would be a pretty easy antenna to build. Uses quite a bit of copper, so it's probably only practical if you have scrap copper around.
Antenna looks works OK at 300ohms, but the Hi-vhf end might would work better at 75ohms.
I tried to set the model up so that it's easy to change parameters, without effecting to much of the rest of the model.
Go ahead and play with it, and see what you can do.
Code:
CM Hi-VHF and UHF antenna made from 1/2" copper tubing and soldered joints.
CM By ljhavener.
CM Based on design from Yurii Pylypenko
CM Has gains of around 7.5db across the Hi-VHF band
CM The UHF stays above 10db for most of the new US Repack band.
CM Uses a lot of copper, so you might consider other
CM build materials and methods.
CM
CM
CM
CE
SY Scale=1.0
SY sc=Scale
SY Rsrc=0.091 'SOURCE Wire Radius, Adjusted for AGT=1.0: UHF(524)=0.09 VHF(194)=0.092
SY Rquad=0.3125 'BiQuad Element Radius 1/2" copper tubing
SY Rrefl=0.3125 'Reflector Element Radius
SY Rbolt=0.125 'Bolt Radius
SY Rwing=0.125 'Wing Radius 1/4" brass rod
SY feedgap=1.0 'Wing Feedpoint Gap Size
SY fgap=4.0 'BiQuad Gap Size 4.0
SY fg=fgap/2 '1/2 element gap
SY winglen=8.0 'wing length 8.0
SY ldlen=10 'Lower diamond element length 10.0
SY ldzdelta=ldlen*.7071 'Lower diamond height
SY ldydelta=ldzdelta+fg
SY spurwidth=1.46
SY sw=spurwidth/2
SY spurhigh=6.186206
SY sh=spurhigh
SY uddelta=ldydelta-sw
SY udlen=uddelta*1.4142
SY udh=ldzdelta+uddelta
SY shz=sh+udh
SY r0length=30.0
SY r1length=30.0
SY r2length=48.0 '47.71
SY r3length=30.0
SY r0len=r0length/2
SY r1zdelta=ldzdelta
SY r1z=ldzdelta
SY r1len=r1length/2
SY r2zdelta=uddelta
SY r2z=r1z+r2zdelta
SY r2len=r2length/2
SY r3zdelta=sh
SY r3z=r2z+r3zdelta
SY r3len=r3length/2
SY rdback=15.0 'distance back to reflector 15.0
SY rdb=rdback
GW 1 5 rdb*sc fg*sc 0*sc rdb*sc ldydelta*sc ldzdelta*sc Rquad
GW 2 5 rdb*sc ldydelta*sc ldzdelta*sc rdb*sc sw*sc udh*sc Rquad
GW 3 3 rdb*sc sw*sc udh*sc rdb*sc sw*sc shz*sc Rquad
GW 20 5 0 0 r1z*sc 0 r1len*sc r1z*sc Rrefl
GW 21 5 0 0 r2z*sc 0 r2len*sc r2z*sc Rrefl
GW 23 3 0 r1len*sc 0 0 r1len*sc r1z*sc Rrefl
GX 999 010
GW 100 1 rdb*sc sw*sc shz*sc rdb*sc -sw*sc shz*sc Rquad
GW 101 3 0 0 r2z*sc 0 0 r1z*sc Rrefl
GX 999 001
GW 200 1 rdb*sc fg*sc 0*sc rdb*sc feedgap/2*sc 0*sc Rwing
GW 201 1 rdb*sc -fg*sc 0*sc rdb*sc -feedgap/2*sc 0*sc Rwing
GW 202 5 rdb*sc fg*sc 0*sc rdb*sc (fg+winglen)*sc 0*sc Rwing
GW 203 5 rdb*sc -fg*sc 0*sc rdb*sc -(fg+winglen)*sc 0*sc Rwing
GW 300 5 0 0 0*sc 0 r0len*sc 0*sc Rrefl
GW 301 5 0 0 0*sc 0 -r0len*sc 0*sc Rrefl
GW 900 1 rdb*sc -feedgap/2*sc 0*sc rdb*sc feedgap/2*sc 0*sc Rsrc
GS 0 0 0.0254
GE 0
LD 5 0 0 0 58000000 'Copper Elements
GN -1
EK
EX 0 900 1 0 1 0 0
FR 0 40 0 0 174 12
RP 0 1 73 1510 90 0 1 5 0 0
EN
I tried to set the model up so that it's easy to change parameters, without effecting to much of the rest of the model.
Go ahead and play with it, and see what you can do.