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clanon
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Everything posted by clanon
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I didn't want to make this antenna! The image was laid out as an example. Make a narrowband - no problem! I wanted a broadband antenna from AL. stripes. The same you built , BUT with FOLDED dipole DIRECTORS...Directional , high Gain , WIDEBAND
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"As an example, consider two adjacent ports, both having reflection of -9.5 dB (VSWR=2:1), resulting in EVM=-19.0dB. From the Figure 1, error limits are +1.0/-0.9 dB and ± 6.4°. By reducing reflection of one of the ports to -20.8dB (VSWR=1.2:1), corresponding to EVM=-30.3dB, error limits reduce to ±0.3dB and ±1.8°. It should be emphasized that amplitude and phase errors are exclusive, namely at a frequency where amplitude error peaks, the phase error is minimal and vice versa." "The effect of changed output VSWR with non-ideal load VSWR reflected by the system will cause additional amplitude and phase errors." PS: we tend to forget that THIS are NO OLD ANALOG RADIOS , Amplitud , PHASE and Frequency are USED for MODULATION (Higher the speed bigger the CONSTELLATION vg : 256QAM) and ALL are adversely affected by VSWR , impedance changes ,etc.You'll notice as a decreased speed due to the need for RE-TRANSMISSION...RXQ in LINUX
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from where...?
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Jomy if you pass the cst i could try make it an 75 ohms LFA dipole...
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You need to locate TWO points in map (New Site 1 and New Site 2) + this info
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you gonna need TWO of those at 90 degrees...+ some separation (a couple of cms)
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nice to try for an ARRAY...4 - 8 of those
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if you choose parabolic dish reflector you'll need any good TWO PORTS feed for that dish (mimo 2Tx2Rx REQUIRES two cables , two antennas or one at 90 degrees between two ports) to get FULL SPEED it maight work okay with just ONE cable-port but NOT FULL SPEED (depends on HOW it was configured , firmware settings)
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Those are 2T2R (mimo) they NEED both antennas to make FULL use of BANDWIDTH sensitivity is better on the 841 (need less gain and power).... Link budget calculates at least 18 dbi gain needed for 17 18 dbm of power and -68dbm sensitivity...
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Line of SIGHT or OBSTACLES , if so , what kind of obstacles , Height you could use , mastil tower... Radio types (router extender power , sensibility) THEN and only then , you know how much gain you'll need...imho
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Jomy try making it a LFA , doing an HORIZONTAL folded dipole , you can make it 50 ohms by that change and dimensions , the rest stays the same (director reflectors)
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wire is SO reactive...
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it should be studied and simulated , since impedance 200 ohms (originally) will be 100 ohms for two ...but 4 of those would make a direct adaptation to 50 ohms (1:1 balun required) and YES
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shabra , what swarg is saying (i think) is that you should MAKE sure that the base of the MED sees a GND (center of grid) at the SAME point like in the BASE station (telecom antenna) which means HOLDING it from OUTSIDE and BEHIND with the circle (director) pointing in to the GRID... And that the lobe of this MED is FAT and goes in two directions (polarizations) meaning that you are spilling some radiation since your reflector (grid) is almost rectangular (Circular would be better to reflect both dipoles) which are at 90 degrees
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HEY JOMY did he say THANKZ or named you...?
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if TOLERANCES (diameters on shield , leads , PCBs) are not maintained , impedance would change. I would solder straight from modem , card to antenna , if possible. Keeping distances as short as possible and impedance (cable shape ,curves) as minimum as possible. ALL connectors have loses imho
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HUMIDITY and MOISTURE inside COAXIAL cable could be a problem...there. over time. a layer of some insulation or cover all in thin PET (nylon) dielectric paint could be better... Cable changes inside due to WATER and you lose SIGNAL
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DISTANCE to REFLECTOR must be TAILORED to local needs...(FR4 quality . reflector enclosure sizes and shapes) but it's on ballpark...i think
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focus point is important (distance to reflector) some mm make a huge difference... did you try with antenna (reflector ) at 90 degrees...VERTICAL...?
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i catched Mikrotik stealing BUT developing over the theft here
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easier to STEAL than develop-invent... nice bandwidth... could it be SHIFTED to 1 ghz (LTE)...? Who needs 3,5ghz...
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That TRENDNET is easier to build and simulate... wouldn't be GREAT to develop an ARRAY bi-band using dipoles...? (15 or more dbi)