Endfed Halfwave or Random Wire
I just moved into a townhouse and received permission from the property manager to install an inconspicuous antenna, with one caveat, the antenna cannot cross over anyone else's townhouse. That leaves me with on direction to go, out over the parking lot directly to my east.
So to the point of this thread, what do you guys think would be better a resonant end fed halfwave connected to an SGC autotuner or a random length of wire stretched as long as possible also connected to the same tuner.
What you want to do is avoid a half wavelength if possible as this will present a very high voltage node at the feedpoint of the tuner and could even damage it. It is better to be a little longer or shorter on an end fed wire. The key to good performance with any end fed wire antenna is the same as it is for a vertical.
You have to have a really good RF ground. That means you need to have a low impedance ground path. A copper ground stake won't do, you need to lay down some wire. The counterpoise wires don't have run under the antenna in fact, they can run anywhere you have room but put down as much wire as you can get away with. Also, if there is a copper water service pipe that comes into your townhouse go ahead and tie that into your ground system.
Be sure to terminate all of the ground connections a a single point as close to the tuners ground connection as you can get them and connect it to the ground lug on the tuner. Don't run the ground into the shack as this can invite a ground loop causing RF to get into your rig and power supply. As long as the tuner is grounded the system is happy.
i'm sorry you don't have the experience or understanding to realize that others possess a skill set that you seem to dismiss as fantastical.
"Random" where random means that it's not a 1/2 wave or multiple thereof at any band.
I think your thought to use a coupler like the SG-230 is an excellent one, and provided you have some counterpoises for it to work against [more or less resonant lengths of wire for each band], it will work.
SGC has a website and some good tips on using their couplers, I recommend it to you, you might even find a more interesting idea or ideas.
One note, while you don't NEED a smartlock control, it's sort of nice to have an indication of when you achieve tune and it's not that hard to build one and put it in a small cabinet.
Unfortunately I am unable to put any real radials down on the ground here, I was going to try a counterpoise hidden in the attic, that is also where the tuner/coupler will be located with the wire feeding out of the gable vent. If anyone has a better "compromise" suggestion for the counterpoise I'm all ears though. Although this location is better for a family it certainly cramps my hobby.
With an end fed random wire you will have a counterpoise whether you intentionally install one or not. If you don't install one, the feedline and townhouse wiring will become the other half of your antenna. Think lots of RFI.
How much power are you planning on running?
You could run your radials in the attic, anything would be better than having none....like the guy said...your feedline and the building wiring system will become the other "half" of your antenna if you don't.
Can you install a vertical up there?
Also since you have access to the attic...can you install a trapped dipole?
FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.”
Flying Pig -57 NAQCC 18 ARCI 10223 SKCC 2076T FISTS 5695 CC 764 SOC 400
What bands would you like to operate?
And can you point us to a satellite photo of your property? http://www.qrz.com/db/AF6PB has one, but is it accurate and if so, which place is yours?
What DPO said. At a 1/2 wavelength resonant frequency, the "fed" end of your antenna will be a high impedance point in the system with high voltages to go along with it. The electrically short conductors and components within the tuner will essentially become part of the fed end of the antenna, and thus the same voltages will be present within the tuner. A good broad range manual tuner MIGHT be able to handle those voltages, but a pi-network auto-tuner like the SGC variety would probably have difficulties that could result in damage due to arcing or exceeded voltage ratings for the components.
Originally Posted by KA4DPO
A 1/2 wavelength antenna would work fine if a matching network, stub, or impedance transformer were used between the tuner and the antenna to "tame" the high impedance and use the tuner for fine-tuning and broader bandwidth.
My favorite mode? Morse, of course.
If the tree in the upper right is tall enough, how about a dipole? One wire where you have the orange line and another to that tree? Feedpoint at your house.
No counterpoise needed.