How did we get from PC Board baluns to an LNA produced in Moscow?
Produce your own. This is novel technique I've never heard before, it seems interesting to me, so I posted it in this balun topic.
It's controversial but sounds promising. You amplify differential signal, so any balun loss after pre-Amp doesn't influence SNR. I didn't find any real world measurements for that, only allegations at some russian DX forums.
Where is the evaluation?
in 1st post. I need to know wideband properties of PCB baluns (several similar types are sold here for $0.6-$1). I've heard controversial claims from local TV/SAT enthusiasts that these PCB baluns work better than ferrite @ 700..860 MHz, but worse at 470-650 MHz. I've also seen many type of DIY baluns at different forums (both PCB and bifilar-wire air type) with claims that they are better than those selling for $0.6.
There are also claims that @ 50 Ohm cable/load they work better than @ 75 etc
Also I wanted to add balun into my HFSS antenna models. Antenna is not Z=300 +j0, it has R different from 300 and X different from 0. I wanna see combined output Zo and optimize antenna/balun as a system, not to assume they are 300 +j0.
If antenna has SWR=2 and balun has SWR=1.5 at given frequency (@ ideal 300 Ohm load), combined SWR can be both >2 and <2 depending how balun R/X combines with antenna R/X
So I simulated one of most popular PCB (made in poland) in HFSS, to see:
1) where are frequency cut-offs, VHF-Hi DVB-T2 might be introduced in my area soon, so people are curios whether these existing baluns will work or not)
2) Wideband impedance curve
3) what is heat insertion loss for FR4. when people DIY PCB balun from better materials (Rogers, Izola, Neltec, foamed PVC) - is it worth or not?
4) is trace/topology from industrial design adequate, or poor designed
Most IL comes from ML (SWR), due to reactances and poor topology (trade-off for miniaturization)
I'm looking for balun+LNA for my 2-bay UHF bowtie project
CM4251 & H2 Hybrid
Existing (at my local market) options are:
1) LNA with ferrite 4:1 balun
2) PCB or ferrite baluns
3) 75 ohm coax-through LNA
Polish PCB balun suits well Uda-Yagi folded dipole, but doesn't suite well bowties.
Polish company Anprel/Dipol modify their bowties line shape to suite their PCB:
it works extremely poor (SWR>5, work poor with LNA, doesn't work with passive balun), you can not acomodate coax cable - you must align it along between TR line
I hope to accomodate my bottle-shaped PCB design with 2bay CM4251-like bowtie
Also want to DIY 1R5D Uda-Yagi from holl_ands album, but since it is extremely high-Q type Yagi, want to verify model with balun.