With the start of the 5G roll out I have recently notices a few sits effected, using 2.3m dishes. Picture pixelation and BER fluctuation between 70% to nothing. On Asiasat 5 all channels are effected to different degree with the stronger TP’s more stable.
Other sites using 1.8, no signal at all. From the various solutions at hand the 1450Mhz Low pass filters on the IF side didn’t do much. Only the expensive waveguide filter on the RF side worked.
You’d need 2 of them (USD250 a pop) if you want V and H + OMT feed and 2 of the old WR 229 Flange LNB’s. This heavy assembly also require additional support for maintaining correct orientation and upright integrity.
Short of going for the IPTV solution, If anybody had any success using the common voltage switching V/H LNBF’s or OCS lnb let us know..
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so whats wrong with using a polariser like we used to do on c band
“Polariser” I forgot about this one. This technology goes back the 80th didn’t think you can still get them let alone a receiver with the polarizer skew control and if anything at a reasonable price.
Keep in mind the audience are mostly aged Italian, Portuguese and Spanish people.
Interesting read....>>
Last edited by B52; 21-08-19 at 04:27 PM.
polarisers were a pulsed 5v radio controll device so it shouldnt be hard to design a circuit for that
I can see all us CBANDERS be effect by this eventually and we should be all compensated depended on on how long we have been doing this as a hobby. It just a case of a BULLY taking over our rights to watch CBand FTA Stuff.
The initial radio frequencies used for 5G in Australia are 3.5GHz and 3.6GHz which are in the existing mobile band. From what I see on the Spectrum Analyser its more like 3650Mhz
admin (02-09-19)
depends on the quality of the bandpass filters but at a guess i would say not as the co channel are closer than this
The harmonic effect of a strong horizontally broadcasted carrier at 3.65GHz is the one that cause the interference through and above 4.2GHz. Going back 15 years ago we had similar issue with Unwired.. at that time a combination of a bigger feed horn and a 1450MHz low pass L Band filter provided relief to most sites. In 2013 Optus bought Unwired and shut it down.
Last edited by B52; 22-08-19 at 11:43 AM.
It will be interesting to see if anyone comes up with a reasonably priced practical solution for the C band hobbyist
I for one am already being affected using a 3m motorised dish in Melbourne
It will be a sad day when C band is no longer viable 😩
You dont have to be affected its pretty easy to have a cavity filter on these frequencies and produce noise free signals ????
Mr 672A (27-08-19)
they are only a length of wave guide with screws in them . the screws are placed at half or one wavelength apart accurate measurements these are screwed in the wave guide to represent antennas that are "shorted " at a particular frequency , ie above the freq and below the freq , this sets the bandwith and the more "antennas" the more accurate the bandwidth , have a little read up on them they are no secret device and easily made
ok Theres nothing inside them just the wave guide with a standard size for c band you can look up the sizes . They are all rated to international sizes as wg (and a number ) which is appropiate to the frequency covered . some are round, some rectangle they have a width and a height to suit the band its used on it acts the same as coax but with lower losses `look at arrl antenna handbook page 18-3
filters are normally quite sharp if the waveguide is made correctly by placing screws in the wave guide in line with the center of the guide at the rite distance apart you can interfere with the frequency you want to attenuate screw in to get action harder or out for softer these are normally brass screws and made to never be able to short both side of the guide together or you have a very low impedance which can be disasterous on a tx the thread is suited for ease of tuning so normally fine threads are used with locknuts the waveguide can be fabricated out of any metal but copper or brass is best for losses but I have made it out of ally without too much problems just beware that it will move with temp and detune . From memory a book by jessop is the bible on this stuff . some have stepped inserts to pull them on to frequency , that is the less standing waves in the antenna the higher the signal for a given frequency thats about enough for the brain today cheers don
B52 (27-08-19)
This...>> dosn't seem to have adjustment screws..
you are right but if you look close you will see that there is a ridge along the length , this puts the tx freq outside the waveguide cutoff so it rejects this . study the figures and you will see the reject freq figures these are the ally type and are good inside but suffer from corrosion outside in the weather . the cutoff freq is a range of high or low impedances if you are going below freq or above the freq this gives a huge loss to a particular freq to reject it , not too confusing yet ? look at the freq to be used on 3.7-4.2 ghz at 0.06db loss yet when you go up to 5.9 ghz you have 50-80 db loss by using screws you can get these figures much tighter in freq Don
Last edited by hinekadon; 27-08-19 at 10:04 PM. Reason: spelling
Here's the one recommended by AsiaSat
ASIASAT 5G INTERFERENCE REJECTION BANDPASS FILTER -
EDIT **** Sorry B52 already publish this on previous post, not able to delete it.
Last edited by Ferjo; 02-09-19 at 02:07 PM.
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