grant hodgson g8ubn a new ao-40 k-band downconverter
TRANSCRIPT
Grant Hodgson
G8UBN
A new AO-40 K-band Downconverter
Grant Hodgson G8UBN
A new AO-40 K-band Downconverter
Topics presented :-
Conventional Downconverter Design
New dual-injection design with new components
New Synthesised Local Oscillator
x5
C o n v e n tio n a l 2 4 G H z D o w n c o n v e rte r
3 s tag e L N A (N F ~ 2 d B ) W a v eg u id e F ilte r
S u b -h a rm o n ic M ix e r
2 .4 G H z L o c a l O sc illa to r
x 5 G a A sF E T M u ltip lie r
2 4 .0 4 8 G H z 11 .9 5 2 G H z
2 .3 9 0 4 G H z
1 4 4 M H z
H a rm o n ic F ilte r
A new AO-40 K-band Downconverter
A new AO-40 K-band Downconverter
•Proven design
•Image frequency is very close to wanted frequency -• Therefore a narrow waveguide filter must be used• Which requires adjusting and aligning
•Local Oscillator multiplier (x4 or x5) requires aligning•Conventional Local Oscillator also requires aligning
Conventional 24GHz Downconverter
A new AO-40 K-band Downconverter
Conventional 24GHz Downconverter
Photo courtesy of Mike, N1JEZ
A new AO-40 K-band Downconverter
24GHz Waveguide Filter
Photo courtesy of Howard, G6LVB
A new AO-40 K-band Downconverter
•Be self-contained - no external LO etc. •No-tune design•Low frequency drift with temperature•Modular design - interchange various system components (LO, LNA etc)•Allow reception of terrestrial Dx at 24192MHz as well as AO-40 K-band downlink (24048MHz)•Use new components that will not become obsolete in less than 5 -10 years
•Encourage experimentation at microwave frequencies!
New 24GHz Downconverter - design objectives
A new AO-40 K-band Downconverter
N e w 2 4 G H z D o w n c o n v e rte rL N A(O p tio n a l) S u rfa c e M o u n t
S u b -h a rm o n ic M ix e r
2 .4 G H z L o c a l O sc illa to r
2 4 .0 4 8 G H z
9 6 7 7 .2 M H z
2 4 1 9 .3 M H z
1 4 5 M H z
x2
x2
4 8 3 8 .6 M H z
4 6 9 3 .6 M H z
4 8 3 8 .6 M H z
5 G H z 2 -w ayS p litte r
F ilte r
2 n d M ix e r(d o u b le b a lan c ed )
L S B
9 6 7 7 .2 M H z x 2 = 1 9 3 5 4 .4 M H z
1 st IF am p
A new AO-40 K-band Downconverter
x2
x2
G a li-3 3
H M C 2 0 4
M G A -8 7 5 6 3
H M C 1 8 9
H M C 2 1 8H M C 2 6 4
G a li-6
P r in te d B a n d p a s s f i l te r
G a li-S 6 62 x M G F 4 9 5 3 A ?
M G F 4 9 5 3 A
G a li-1
P rin ted W ilk in so nS p litte r
A new AO-40 K-band Downconverter
Harmonic suppression of HMC204 doubler
A new AO-40 K-band Downconverter
Wa nte d fre q ue nc y
100M Hz
Inte rm e d ia tefre q ue nc y10M Hz
Lo c a lO sc illa to r90M Hz
Im a g efre q ue nc y80M Hz
Wa nte d :-IF = RF - LO 100 - 90 = 10
Im a g e re sp o nse :-IF = LO - im a g e 90 - 80 = 10
Brief overview - image response of mixers
A new AO-40 K-band Downconverter
A new AO-40 K-band Downconverter
N e w 2 .4 G H z L o w P h a se N o iseP h ase L o c k e d L o o p S y n th e s ise r
2 .4 G H z V C O2 4 1 9 .3 M H z
1 3 M H z U ltra L o w P h a se N o iseO v e n C o n tro lle d C ry s ta l O sc il la to r (O C X O )
/1 0
/1 8 6 1
L o o p F ilte r
V C O D C C o n tro l Vo ltag e
2 4 1 9 .3 M H z / 1 8 6 1 = 1 .3 M H zP h a s e L o c k e d L o o pIn te g ra te d C irc u it :- P ro g ra m m a b le re fe re n c e d iv id e r P ro g ra m m a b le m a in d iv id e r D u a l m o d u lu s p re sc a le r P h a se /F re q u e n c y D e te c to r O th e r fu n c t io n s (n o t u s e d )
1 .3 M H z R e fe ren c e F re q u en c y
A new AO-40 K-band Downconverter
•Difficult choice at 24GHz•Various options, but probably :-
•Separate (external) LNA Duroid, Taconic or Similar
•Main PCB on std. FR4 fibreglass
PCB
A new AO-40 K-band Downconverter
•Most of the design objectives have been met
•Next step is circuit design and prototyping
•Waveguide image filter has been eliminated
•True no-tune design
•Operation on K-band should become easier, •whilst still leaving lots of room for investigation and experimentation
Summary