Returning back to Ham radio after a 40 year hiatus. Looking for input on the potential use of an inverted V for 10 meters placed in the attic. My attic is not the most antenna friendly place for a conventional horizontal dipole (i.e. HVAC, misc wiring, etc.), but it does have a rather high center gable. My design is to make a 90 degree inverted V dipole. Apex will be 25-30 feet above the ground which would then put the end of the elements approximately 5 feet below that. Further, in lieu of tethering the ends of the elements to the floor of the attic I was instead going to use a piece of PVC pipe and connect the ends of the legs directly to that at the correct geometrical distance. The PVC is nonconductive and will act as the "base" of the triangle while maintaining the correct antenna configuration. That would also simplify final tuning.
That sound like a plan. Inverted-V antennas tend to be more omni-directional than a dipole, and radiates equally in all directions. But all of the conductive items in the attic may alter that a bit.
The "V" configuration has a shortening effect, in that, you will probably have to shorten the elements to bring the operating frequency to the right frequency. Again, the nearby conductive items in the attic may alter that a bit.
As long as you keep the apex angle between 70 and 110 degrees, the antenna should work fine. Below 70 Degrees the radiators start to become parallel to each other and signal canceling will start to occur. Above 110 Degrees the antenna starts looking like a standard dipole.
You can tie the coax directly to the wires at the feed point. However, it is best to use a 1:1 balun at the feed point. The normal feed impedance for a dipole is around 70 Ohms, but the "V" configuration tends to reduce that and can give you a very nice 50 Ohm impedance.
Martin - K7MEM
