Also known as: J-mount, J-pole mount, wall bracket, eave bracket
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An eave mount — usually a J-mount or J-pole bracket — is an L- or J-shaped steel arm that bolts to a wall, eave, or fascia and holds a short antenna mast a foot or two out from the structure. It is the simplest and cheapest outdoor mount, and the only one on this list that needs no roof penetration: you lag it to solid framing on a vertical surface and stand a scanner antenna up under the roofline. For a lot of base installs it is all the mounting hardware you need.
What it is
The classic bracket is a single steel bar bent into a “J” or an offset “L”. One leg bolts flat to the wall through pre-drilled holes; the other stands proud and carries a short mast — often about 1 inch in diameter — clamped with a U-bolt. Reach from the wall is typically around 20 inches, enough to clear an eave, gutter, or overhang so the antenna sees a clean horizon.
For a heavier or slightly taller pole, the same idea scales to a two-bracket wall mount: two brackets lag-bolted to the same wall a couple of feet apart, with the mast passing through both. That spacing does the real work — the vertical distance between the two clamp points is what resists the wind’s leverage on the mast, the same principle a chimney strap mount uses with its two straps.
How it mounts
A wall bracket lives or dies by what it bites into. Lag bolts must reach studs, rafter tails, or solid blocking — never just siding or sheathing, which will pull out under wind load. Mount it as high on the wall or gable as you can while still hitting framing, so the antenna gets near the ridgeline. Use stainless or galvanised fasteners outdoors, and seal the bolt holes.
Because the bracket and mast are metal, they should be tied into a grounding kit like any other outdoor antenna support, and the coax coming down should pass through a lightning arrestor where it enters the building. General mast clamps and U-bolts let you attach the antenna and dress the feedline down the wall.
Relevance to GopherTrunk
Like every mount, the eave bracket is invisible to GopherTrunk — but it is often the quickest route to getting an antenna out of the attic and into the clear, which is where marginal P25 and TETRA sites start decoding. If you have a gable end or eave facing open sky, a J-mount plus a discone is a weekend upgrade that can transform what your SDR hears. It will not, of course, do anything for encrypted traffic — no antenna or mount can.
Where to buy
For a wall or eave install, a 20” universal J-pole bracket (around $16) is the standard, inexpensive answer: lag it to solid framing, clamp a short 1-inch mast, and you have a discone up under the roofline with no roof penetration. Step up to a two-bracket wall mount if you want a slightly taller or heavier pole.
See the mast and mounting guide for how the bracket fits into a full outdoor stack, and the outdoor base build for a complete parts list.
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Frequently asked questions
Which eave / J-mount should I buy for a scanner antenna?
A 20” universal J-pole wall/eave bracket (around $16) is the standard pick: a J-shaped steel arm that lag-bolts to a wall, eave, or fascia and holds a 1-inch mast about 20 inches out from the surface. It is the cheapest way to get a discone or vertical up under the roofline without drilling the roof itself.
Can an eave mount hold a tall mast?
No — a single wall bracket is for a short mast, roughly 5 ft above the top of the bracket. Two brackets spaced a couple of feet apart on the same wall (a double-bracket wall mount) will steady a taller pole, and anything beyond about 10 ft of exposed mast wants a guy wire kit as well. The bracket is a base, not a tower.
Where should I put a J-mount?
As high on the structure as you can while still reaching solid framing — under the eave or on the gable end typically gets the antenna near the ridgeline without a roof penetration. Bolt into studs or solid blocking, not just siding, and stand the mast off far enough that the antenna clears the eave and gutter.
Eave mount or tripod?
Use an eave/wall bracket when you have a suitable vertical surface near the roofline and want to avoid drilling the roof; it is cheaper and simpler. Use a tripod when the only clear spot is a flat roof or deck. Both hold the same short mast — the choice is about what your structure gives you and whether you want a roof penetration.