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log periodic
- Thread starter rfoverlord
- Start date
rfoverlord,
They are nice antennas, but I don't have one. Wish I could afford, and had the space required for one that I'd have a use for, but... if I had that kind of space, I probably wouldn't have to worry about what the thing would cost.
My 'active' area is the lower HF bands, not a lot of the higher HF bands or VHF/UHF, so a log would be huge for what I'd want it for. Even with loaded elements that would be something at least 60 feet wide, sort of.
The attractive thingy about log periodics is that they can be used on a very wide range of frequencies/bands. No retuning for band changes, at least one element on each band. Sort of the equivalent of a two element beam on each band. Directional, yes. Some gain but not a lot, yes. Much easier to 'do' on VHF/UHF. Until things sort of went to satellites, the Navy had them on most of their land stations (humongus things!). The other services probably did too, but I know the Navy did. They also covered the HF bands. But then, they used Rohn 25 for the boom, so it wasn't a couple of hours thing to raise them, you know? And the rotor wasn't something I even want to think about!
Still like to have one, but where would I put it??
- 'Doc
They are nice antennas, but I don't have one. Wish I could afford, and had the space required for one that I'd have a use for, but... if I had that kind of space, I probably wouldn't have to worry about what the thing would cost.
My 'active' area is the lower HF bands, not a lot of the higher HF bands or VHF/UHF, so a log would be huge for what I'd want it for. Even with loaded elements that would be something at least 60 feet wide, sort of.
The attractive thingy about log periodics is that they can be used on a very wide range of frequencies/bands. No retuning for band changes, at least one element on each band. Sort of the equivalent of a two element beam on each band. Directional, yes. Some gain but not a lot, yes. Much easier to 'do' on VHF/UHF. Until things sort of went to satellites, the Navy had them on most of their land stations (humongus things!). The other services probably did too, but I know the Navy did. They also covered the HF bands. But then, they used Rohn 25 for the boom, so it wasn't a couple of hours thing to raise them, you know? And the rotor wasn't something I even want to think about!
Still like to have one, but where would I put it??
- 'Doc
The only thing about LPDA's is that the gain is significantly lower than what a similar number of elements on even a tribander would give you. That is the trade off against bandwidth.
Hey Doc,I have a naval TX station,callsign CFH, about 12 miles from here. In addition to the HUGE LF antenna and several Rhode and Swartz HF arrays they have three Rhode and Swartz log antennas good for 3-30 MHz. The boom is tower section and supports wire elements that are full sized for the freqs used.The rotator is about the size of a Volkswagon Beetle.
Hey Doc,I have a naval TX station,callsign CFH, about 12 miles from here. In addition to the HUGE LF antenna and several Rhode and Swartz HF arrays they have three Rhode and Swartz log antennas good for 3-30 MHz. The boom is tower section and supports wire elements that are full sized for the freqs used.The rotator is about the size of a Volkswagon Beetle.
Well thats kinda my problem, space, i figured it will be the best bang for the buck. Since i wanted the warc bands also, 2 ele. is better than a dipole. I am also mounting a 8ele. 2mtr. & 70cm. above it. Yes i have seen some seriously massive arrays used by AT&T and a govt. facility. rohn 25 size booms was on the small ones. the towers these beast were on, the service trucks & vans could park side by side inside the tower bases i couldn't even guess how big the booms were. I couldn't get close enough without atracting attention to my self. that was outside of Denver.
Depending how important 30 meters is to you, you might want to consider a two-element quad. Mine, with about 9-1/2 feet between driven element and reflector, does extremely well on 20/17/15/12/10.
Beetle, I had originally considered a quad but once again space being a premium, since i have 4 ants. to put up all on the same tower for now it will have to be yagi style for stacking purposes. It really sucks having 3 towers with no place to put them all up unless i want the whole family commuting, instead of just me.
I own and used a KLM Log. Used it when I was in the Navy. Never put it up at home. They work great and are basically a 2-element beam on all frequencies.
They are great for some purposes and a compromise for others.
Check this one out:
http://realhamradio.com/Log_Periodic.htm
They are great for some purposes and a compromise for others.
Check this one out:
http://realhamradio.com/Log_Periodic.htm
Master chief, thanks for the read. it was informative. I still haven't decided which one of the tennadynes i will get, the t-6 is the easiest to deal with, but i'm seriously leaning to something with a longer boom just for the reasons stated in the article.
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