dmg1969
Member
It doesn't seem to affect It. II would be hard pressed to find an area of that attic away from electrical wiring anyway. I am hearing traffic from fairly far away.
Dave
Dave
My homemade Off Center Dipole Antenna
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Dave- One other thought... now that you have gone to the trouble of routing the coax up to the attic, you may want to leave it there and use new coax when you move the OCFD to the roof. Reason is that you may find in the future that you'd like to have another antenna.... maybe not OCFD... in your attic in the future. Would make it much simpler to install in attic again.
dmg1969
Member
I'm not sure if and when I am going to move it outside. The only band I seem to have trouble with is VHF low and I think it's just simply a terrain issue. Sometimes I hear the one police department loud and clear, other times not so great and other times not at all. I think it just depends on where the unit is. The other PD is even further away and I never hear them.
Dave
Dave
Thanks for posting this, Dave. I built one two weeks ago using your instructions and have been moving it around from room to room to see where the best reception is. I am still trying to improve my reception of the Dauphin system. Perhaps I will try the shorty version and see if that helps.
dmg1969
Member
No problem. I am still using it as my antenna for my BC355N in the house. For me, it is a good alternative to an outside antenna. I'm happy with the results I get.
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thesk- so how did it work for you?
thesk- so how did it work for you?
Other than buying a weatherproof balun designed for outdoor use, why would you need to weatherproof the antenna more than just painting the copper to prevent oxidation?
dmg1969
Member
Hey thesk. It is a fun little project, huh? Many here have made it. How is your receiving? Mine is not currently hooked up, but still in the attic. I put an actual Hustler mobile wide band antenna up there. It was on my vehicle and the coax was slightly damaged, so I got a new one and used the old one as my attic antenna. I have been meaning to put another coax run in and use the OCFD as a second antenna if I want to hook my portable as a second scanner in the house.
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rudyizcool
Member
Thank you!!
I want to thank you for posting your dipole antenna instructions and photographs! It made it very easy for me to construct my first antenna for scanner listening! I am not a licensed amateur radio operator, but have been a radio hobbyist since I was 12-years-old...about 35 years ago. I listen to shortwave and scanner radios. Thought about getting a license, but just can't seem to get over the horror of the mathematics and equations used for the hobby. I'm not ignorant, and yet I'm not Einstein either lol. Maybe some day.
But yes, your antenna creation is working great for me! For about a month I've been reading up on certain Yagi antennas to use in order to receive the Brazilian pirates using the US military satellites. And guess what? Your dipole antenna allowed me to pick up my very first pirate communication 2 days ago!!! YES! Now I don't have to mess with a Yagi (unless I change my mind), because this antenna seems to work quite well. Of course, the signals fade in and out sometimes, and at other times I get crystal clear reception for a few hours. This may be due to atmospheric conditions as with all radio communications?
Again, thank you for posting this awesome antenna creation, and I'll be using this simple, portable dipole for a long time!
I want to thank you for posting your dipole antenna instructions and photographs! It made it very easy for me to construct my first antenna for scanner listening! I am not a licensed amateur radio operator, but have been a radio hobbyist since I was 12-years-old...about 35 years ago. I listen to shortwave and scanner radios. Thought about getting a license, but just can't seem to get over the horror of the mathematics and equations used for the hobby. I'm not ignorant, and yet I'm not Einstein either lol. Maybe some day.
But yes, your antenna creation is working great for me! For about a month I've been reading up on certain Yagi antennas to use in order to receive the Brazilian pirates using the US military satellites. And guess what? Your dipole antenna allowed me to pick up my very first pirate communication 2 days ago!!! YES! Now I don't have to mess with a Yagi (unless I change my mind), because this antenna seems to work quite well. Of course, the signals fade in and out sometimes, and at other times I get crystal clear reception for a few hours. This may be due to atmospheric conditions as with all radio communications?
Again, thank you for posting this awesome antenna creation, and I'll be using this simple, portable dipole for a long time!
Glad it works for you! Ya' never know, it can inspire further antenna projects that are more specialized.
Whatever you do, make sure you use at least RG-6 or better as the feedline (no rg-58/59 please!), and make it as short as possible to reduce loss.
The additional swr loss combined with the matched line loss can start to add up on this antenna pretty quick. Ideally, one should use hardline with the ocfd, but that would probably be pretty fooli$h for 99.999% of the people.
Whatever you do, make sure you use at least RG-6 or better as the feedline (no rg-58/59 please!), and make it as short as possible to reduce loss.
The additional swr loss combined with the matched line loss can start to add up on this antenna pretty quick. Ideally, one should use hardline with the ocfd, but that would probably be pretty fooli$h for 99.999% of the people.
dmg1969
Member
Sure thing, rudyizcool. I'm glad you were able to build it and that it is working out for you. I can't take any credit for the antenna...just followed the directions I found here on RadioReference and took my own pics for reference. I still have to hook mine back up. Just not look forward to crawling into that tiny little attic. But I'd better do it before the real heat starts.
P.S. I am not into amateur radio either. I have just been a scanner enthusiast since I was 10 or 11...also a mere 35+/- years ago.
rudyizcool
Member
Glad it works for you! Ya' never know, it can inspire further antenna projects that are more specialized.
Whatever you do, make sure you use at least RG-6 or better as the feedline (no rg-58/59 please!), and make it as short as possible to reduce loss.
The additional swr loss combined with the matched line loss can start to add up on this antenna pretty quick. Ideally, one should use hardline with the ocfd, but that would probably be pretty fooli$h for 99.999% of the people.
Thanks for the advice! You did mention the use of RG-6. I have been using 25 feet of RG-59, and noticed a loss in the shortwave bands (not sure if this dipole is for shortwave frequencies, yet it does faintly receive some). I'm using a Yupiteru MVT-7100, which I know is a sensitive receiver anyway. I have connected an Archer coax cable, RG-6, that I found up in my attic....about 25 feet. Is this too long, or good enough? You mentioned the cable should be as short as possible. I'm going to monitor the radio throughout the day with the RG-6 and see if the UHF satellite bands are still audible. I'm hoping they are so I can keep using the RG-6.
Toss the RG-59. RG-6 is a minimum unless your ocfd is only a few feet away.
The antenna is not designed for swl, and the main resonant freq is in the FM broadcast band, which could be an overload issue for some without a filter. However, because it is so inefficient for swl duties, what you hear comes mainly from the common-mode (outside skin of the braid), it may be ok for portables that have a tendency to overload with decent antennas.
Ideally, use the least amount of coax cabling as you can, but since this is a compromise antenna, don't go overboard unless you want to.
The antenna is not designed for swl, and the main resonant freq is in the FM broadcast band, which could be an overload issue for some without a filter. However, because it is so inefficient for swl duties, what you hear comes mainly from the common-mode (outside skin of the braid), it may be ok for portables that have a tendency to overload with decent antennas.
Ideally, use the least amount of coax cabling as you can, but since this is a compromise antenna, don't go overboard unless you want to.
voxiso
Member
How well would this work for the 450-460 range?
dmg1969
Member
I had no problem at all pulling in UHF frequencies from a neighboring county.
fourthhorseman
Member
Im a little confused,Which section of this OCFD is attached to the center pin of the connector and which to the shielding?
I was inspired to make one after seeing yours,It really was a breeze.Cut,Drill & Assemble..But Im hung at the final connects..And unclear as to the necessity of the Balun.
I was inspired to make one after seeing yours,It really was a breeze.Cut,Drill & Assemble..But Im hung at the final connects..And unclear as to the necessity of the Balun.
n4yek
Member
The feed point impedance of the OCFD is around 300 ohms, your coax is 75 ohms....hence the necessity of the balun.
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fourthhorseman
Member
Thank You..That makes the clearest sense Ive read,
Any thoughts on the question about hook-ups,Which would be the reflector & which would be the,I guess - Driven- element?
Any thoughts on the question about hook-ups,Which would be the reflector & which would be the,I guess - Driven- element?
GrumpyGuard
Member
The Tech license is not that difficult. You just need to pass a simple 35 question test. There are plenty of websites that have practice tests. Not much math needed. You may only have two math questions on your test, so I would not stress out on the math.
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