KPC FIELD TOOL

ANTENNA PATTERN & SWR

Pick an antenna, a band, how high it is and what is under it. See where the signal goes (DX or nearby), a rough SWR curve and how much your coax eats, before you ever leave the house.

ANTENNA FREQUENCY (MHz) WIRE CUT FOR HEIGHT (ft) GROUND WIRE LENGTH (ft) SLOPE (° below horizontal) RADIALS RAISED RADIALS RADIAL DROOP (°)

PEAK GAIN (ESTIMATE)–

BEST TAKEOFF ANGLE–

SWR AT YOUR FREQUENCY–

2:1 SWR BANDWIDTH–

Side view (elevation)

Distance from the center = signal strength. Low angles near the ground line reach far away (DX). High angles straight up fill in nearby (NVIS).

Top view (azimuth) at the best angle

Estimated SWR across the band

Feedline loss

COAX LENGTH (FT) POWER (W)

LOSS IF PERFECTLY MATCHED–

EXTRA LOSS FROM SWR–

TOTAL COAX LOSS–

POWER REACHING ANTENNA–

How to read this (and how far to trust it) This is a quick estimator using standard antenna theory (ground reflection with real-ground numbers, simple feed-point models), not a full NEC simulation. Expect gain within about 1–2 dB and SWR that is right in shape but not in exact numbers. Trees, nearby metal, coax length, a feedline choke and your actual ground change real results, so always check with an antenna analyzer. Random-wire and multiband end-fed numbers use a simple wire-as-transmission-line model: they show which bands are easy or hard, not exact SWR. Coax loss uses the same published cable figures as the Antenna Calculator. Working on a vertical? See how many radials and how long.