| Author |
Message |
    
Bigbob
| | Posted on Tuesday, July 08, 2003 - 9:03 pm: | 
|
How big would a dish antenna be for 11-meters? |
Kc0gxz
| | Posted on Tuesday, July 08, 2003 - 10:26 pm: |
|
Bigbob
40 feet across might do it. Maybe. Give or take a few feet. Maybe.
Jeff, kc0gxz. |
bruce
| | Posted on Tuesday, July 08, 2003 - 10:47 pm: |
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Ok based on ve3ont's numbers for dish gain at 50 mhz a 300 foot dish would give 25 dbi gain at cb a 150ft 19dbi, a 75ft 13dbi so a 40 foot about 7 dbi I think this explains why dishs are not used at hf!
bruce |
Kc0gxz
| | Posted on Wednesday, July 09, 2003 - 1:28 am: |
|
bruce
I guess you can't make it much more clearer than that. You convinced me.
Jeff, kc0gxz. |
151southern ind
| | Posted on Wednesday, July 09, 2003 - 11:34 am: |
|
bruce is right,
they need to be large 10x+ to produce any gain worth while. alot of what ive studied on parabolic ant.most call for the dish to be 10 times larger than the driven element.(when using dipoles ect)so a 18' driven element would call for 180' dish so to speak. also as stated by bruce the bigger the dish the more gain and the smaller the less gain it will have.
even using a 9'3" quad loop for a driven element you would have 93' for the dish. awefully massive to put behind the house...
the closest thing ive found at cb freq's that works well is a screen.
and its intented use was to increase ftb ratio without the loss of forword gain.this is not to be confused with a "rejection kit" that was made for the moonrakers, witch are junk imo because it's inter loops are confusing the antenna. it see's these as directors instead of as a reflector and will put more gain out the back of the antenna with there use.
ive done some tests with these to put and end to this debate at least in my circle of radio buddy's using mfj259 and feild strength meters.
we plotted it out by counting off paces to reach a given power point on the meter,and noted it.we did this 360 deg around the beam for both "with" and "with out kit" antenna.
we used the same antenna just taking the kit off for the next test.
later bullet |
glaxan
| | Posted on Wednesday, July 09, 2003 - 5:27 pm: |
|
WOW then if I hook up my 2980 to the Steerable Array then.... |
bruce
| | Posted on Wednesday, July 09, 2003 - 8:42 pm: |
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How about a 48 foot moonbounce dish!
http://www.nitehawk.com/rasmit/n2iqu.jpg
|
Bigbob
| | Posted on Thursday, July 10, 2003 - 6:26 am: |
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Wow,I'll get right on it,150' dish,hmmm,I think I'll have to check with the local airport. |
bruce
| | Posted on Thursday, July 10, 2003 - 7:35 am: |
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bigbob dishes have this use too...
http://www.satsig.net/seticalc.htm
|
Sixkiller505
| | Posted on Thursday, July 10, 2003 - 8:47 am: |
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so bruce this other company that has one for sale,from a well know manufacting co for 79.95 is a washout, hoax,a joke,etc etc??? if anyone is interested in the web site e-mail me(see my profile)you would be very surprise to see the company(well know too!!) that offers one,it claims to be a 1/2 wave CHECK IT OUT!! SIXKILLER 505 ps and it ain't as big as you say it needs to be either |
bruce
| | Posted on Monday, July 14, 2003 - 7:27 am: |
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I went and found this marvil of engineering what a joke will someone PLEASE work toward a standard for ant gain !!!!!! GOSH next jogunn will have a 6 inch dish for 75 meters! |
Rippedradio
| | Posted on Tuesday, July 15, 2003 - 5:17 pm: |
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thats nothin a 48 foot dish, last month on ebay i saw a piece of land in colorado on a montian top with a 106" dish on top of this building which was like 6-7 stories high!!! now thats what i call a shack and an antenna!!!!! this thing was used for satellite uplinking had a bunker underneath i guess in case someone tried to blow it up?? ya well it sounds really cool but it cost over a million!!! think the wife would mind????? 73's chris |
bruce
| | Posted on Wednesday, July 16, 2003 - 2:41 pm: |
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My kinda antenna just wish seminole wasn't so backward.....here if its more that 35 foot forget it..... and lets not forget lighting ZAP! |
frasiercrane
| | Posted on Thursday, July 17, 2003 - 4:13 pm: |
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jogunn...lololol!!! Not to mention the outrageous RF gain claims, I remember their antenna ads specifying AUDIO gain..lololol!!! |
bruce
| | Posted on Friday, July 18, 2003 - 9:06 am: |
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EVERYONE knows my disdain for JO GUNN sorry but i dont like the idea someone would spend large amounts of money for junk. sure its buyer beware but lets be fair too and even antenna makers need to be reigned in and held for false gain be it rf or AUDDDDDDDDO!
|
Bullet
| | Posted on Saturday, July 19, 2003 - 1:41 am: |
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bruce,
i call them as i see them!!!!!!!
jo junk, jojunk jojunk jojunk jojunk jojunk...... |
