This is question demanding an answer.
Many occasions had seen the antenna construction drawings into internet what forces me to think about author competence. Would it be happen I have stepped in the same mistake (to believe ant written) again?
So, I find the site telling very interesting vertical quarter wave dipole. Standard in such situation is coaxial with lambda quarter multiplied with shortening factor about 0.95...0.98 with taken off braiding and santech copper-pipe down with length of other lambda quarter with cable genuine shortening factor. Cable down must contain at least a coil of some 5-7 turns or ferrite core over cable surplus coil wound of cable as it is. But this website told, it is possible to feed the lower part straight from below, thus the copper pipe is unnecessary. Thus, lower part is fed straight from output of coaxial coil, whilst upper part is fed in the middle, where upper and lower parts comes near. Made it, switched to VNA and see the hedgehog`s coat - needles over needles (below the hundred by count) up to horizon down and up by frequency.
So, may it be that antenna construction belongs those class of ""non-working" or the problem is cased that antenna ends in the PL252 whilst VNA with SMA. Thus I had to have SMA to PL252 converter, then PL259 to PL259, then PL252 to antenna. Thus the plug to plug reshaping parts are probably too much and that what I see probably are reflections between badly made Chinese plugs?? Just I obtained those and this was first trial with those plug converters.
For to provide the standard test of plug-to-plug re-shapers quality I need a 50 Ohm ultra-good reference load into PL252 shape, whilst all mine are in shape of SMA. Thus I cannot to test it. So, what are thoughts do the antenna is faulty or testing cabling is faulty, or both?
P.S. Today the post office made a surprise, arrived one year ago paid parcel from China with right plug in one-piece. Result on the VNA is the same. Pictures attached.
PPS: find one similar antenna construction what is written in manner making easy to believe: https://www.vic.wicen.org.au/?page_id=1353 and found many similar as well, thus seems it isnt the an-alphabetical construction claim. But then what else?
PPPS: My target is 165 +/- 9 MHz range; thus BW=18 MHz (quite much).
PPPPS: Okay, You may suspect me blamed on calcs? My cable is LMR-400, v(f)=0.85, solid teflon, inner d 2.8 mm, outer 10.3 mm. Thus the lambda=1.82 and upper part (physical) length is 455 mm. Lower part (electrical) is 455*0.85=386 mm. Correction for Large Unknown 5% makes both parts 477 mm and 406 mm. Coil contains 5 turns on 30 mm PVC canalization white-pipe. That is all. Okay, may apply the nude wire V(f)=0.97 and 0.95 for plastic pipe covering the upper radiator - what gives out the 440 mm and 406 mm. Checked em too.
PPPPPS: Read about coaxial coil inter-turn gap has a strong impact - if gap-less turn to turn then VSWR is lower but sharper, whilst if coil is gapped, VSWR is not so low but much wider. Read my 5 turns on 30 mm makes coil resonant at 136 MHz what is more than demanded 5-6% under the operating frequency. No, may not blame the coil.
PPPPPPS: at last decomposed the antenna with idea that probably cable bending place where it becomes a coil was too sharp and probably double braiding one layer had been broken. Made a hari-kiri to cable. No, it wasn`t, however there was about 1 mm deep compression crater in the teflon insulator, thus some minor reflection may take a place.
PPPPPPPS: had an idea, this antenna demands a rather long cable about 20 meters, thus I rolled it to the coil on the shoulder. Now I de-coiled that maximum straight and picture wasnt changed not for a yotta. Still in my BW=18 MHz stays 3 waves with R=5 Ohm to 20 Ohm; X=-125 Ohm at all frequencies and VSWR 6...60. Catastrophic.
Many occasions had seen the antenna construction drawings into internet what forces me to think about author competence. Would it be happen I have stepped in the same mistake (to believe ant written) again?
So, I find the site telling very interesting vertical quarter wave dipole. Standard in such situation is coaxial with lambda quarter multiplied with shortening factor about 0.95...0.98 with taken off braiding and santech copper-pipe down with length of other lambda quarter with cable genuine shortening factor. Cable down must contain at least a coil of some 5-7 turns or ferrite core over cable surplus coil wound of cable as it is. But this website told, it is possible to feed the lower part straight from below, thus the copper pipe is unnecessary. Thus, lower part is fed straight from output of coaxial coil, whilst upper part is fed in the middle, where upper and lower parts comes near. Made it, switched to VNA and see the hedgehog`s coat - needles over needles (below the hundred by count) up to horizon down and up by frequency.
So, may it be that antenna construction belongs those class of ""non-working" or the problem is cased that antenna ends in the PL252 whilst VNA with SMA. Thus I had to have SMA to PL252 converter, then PL259 to PL259, then PL252 to antenna. Thus the plug to plug reshaping parts are probably too much and that what I see probably are reflections between badly made Chinese plugs?? Just I obtained those and this was first trial with those plug converters.
For to provide the standard test of plug-to-plug re-shapers quality I need a 50 Ohm ultra-good reference load into PL252 shape, whilst all mine are in shape of SMA. Thus I cannot to test it. So, what are thoughts do the antenna is faulty or testing cabling is faulty, or both?
P.S. Today the post office made a surprise, arrived one year ago paid parcel from China with right plug in one-piece. Result on the VNA is the same. Pictures attached.
PPS: find one similar antenna construction what is written in manner making easy to believe: https://www.vic.wicen.org.au/?page_id=1353 and found many similar as well, thus seems it isnt the an-alphabetical construction claim. But then what else?
PPPS: My target is 165 +/- 9 MHz range; thus BW=18 MHz (quite much).
PPPPS: Okay, You may suspect me blamed on calcs? My cable is LMR-400, v(f)=0.85, solid teflon, inner d 2.8 mm, outer 10.3 mm. Thus the lambda=1.82 and upper part (physical) length is 455 mm. Lower part (electrical) is 455*0.85=386 mm. Correction for Large Unknown 5% makes both parts 477 mm and 406 mm. Coil contains 5 turns on 30 mm PVC canalization white-pipe. That is all. Okay, may apply the nude wire V(f)=0.97 and 0.95 for plastic pipe covering the upper radiator - what gives out the 440 mm and 406 mm. Checked em too.
PPPPPS: Read about coaxial coil inter-turn gap has a strong impact - if gap-less turn to turn then VSWR is lower but sharper, whilst if coil is gapped, VSWR is not so low but much wider. Read my 5 turns on 30 mm makes coil resonant at 136 MHz what is more than demanded 5-6% under the operating frequency. No, may not blame the coil.
PPPPPPS: at last decomposed the antenna with idea that probably cable bending place where it becomes a coil was too sharp and probably double braiding one layer had been broken. Made a hari-kiri to cable. No, it wasn`t, however there was about 1 mm deep compression crater in the teflon insulator, thus some minor reflection may take a place.
PPPPPPPS: had an idea, this antenna demands a rather long cable about 20 meters, thus I rolled it to the coil on the shoulder. Now I de-coiled that maximum straight and picture wasnt changed not for a yotta. Still in my BW=18 MHz stays 3 waves with R=5 Ohm to 20 Ohm; X=-125 Ohm at all frequencies and VSWR 6...60. Catastrophic.
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