Emergency/Go-Kit Antenna
This isn't one antenna design - it's a system for having a working antenna on hand no matter what you're asked to support: an ARES/RACES activation, a repeater outage, a family emergency where cell service is down, or a simple grab-and-go bag for camping season. The kit pairs a lightweight end-fed half-wave (EFHW) wire for HF with a roll-up J-pole for VHF/UHF, both mast-free or near-mast-free, both packable into a small bag, and both deployable by one person in well under fifteen minutes.
Deploy speed and simplicity beat peak performance
A go-kit antenna's most important spec isn't gain or bandwidth - it's how fast and reliably one tired person can get it into the air in the dark, in bad weather, without a truck full of tower sections. Every design choice in this kit favors fewer parts, fewer failure points, and faster setup over squeezing out the last few dB a more complex antenna might offer.
Why an EFHW for the HF half of the kit
An end-fed half-wave wire needs only one support point instead of two (unlike a center-fed dipole), can be deployed as a sloper, inverted-L, or flat-top depending on whatever's actually available on scene - a tree, a fence post, a vehicle mirror - and covers multiple harmonically related bands from a single length of wire and a single 49:1 unun transformer.
Feed impedance at the wire end: ~2,500-5,000 ohms -> needs a 49:1 unun
Why a roll-up J-pole for the VHF/UHF half
The roll-up J-pole already built on this site is the natural VHF/UHF companion for this kit - built from twin-lead or ladder line, it rolls into a small bundle, needs no rigid support beyond something to hang it from, and gets you onto local repeaters or simplex the moment you're on scene, while the EFHW is still going up.
- Roll-up J-pole: up first, local/repeater coverage within minutes.
- EFHW: up second, regional/HF coverage once you have a few more minutes and a support point.
Power independence matters as much as the antenna
An antenna kit built for emergencies is only half the picture - pair it with a radio and power source that don't depend on commercial power, since that's usually exactly what's unavailable in the scenarios this kit is built for. That's outside the scope of this antenna guide, but it's worth planning alongside it.
Installation options
- Tree/natural support deployment: the fastest option when available — throw the EFHW's far end over a suitable branch and hang the J-pole from a lower one.
- Vehicle-based deployment: a roof rack, trailer hitch mast mount, or even a mirror can anchor the low end of the EFHW or support the J-pole when no natural support exists.
- Collapsible pole deployment: a compact telescoping mast extends this kit's usefulness to bare, treeless sites at the cost of one more item to carry.
| Component | Typical size/length | Notes |
|---|---|---|
| EFHW wire (40m) | ~65.5 ft (20.0 m) | Covers 40m and harmonically related higher bands |
| EFHW wire (20m) | ~33.1 ft (10.1 m) | Shorter, easier single-support deployment in tight sites |
| 49:1 unun | Compact, palm-sized | Matches the EFHW's high feed impedance to 50-ohm coax |
| Counterpoise wire | ~lambda/20 minimum | Short counterpoise at the feedpoint, part of the EFHW system |
| Roll-up J-pole (2m) | ~62 in radiator + stub | See the dedicated roll-up J-pole guide for full dimensions |
| Support line/throw weight | 50-100 ft paracord + weight | For getting the EFHW's high end over a branch or other support |
Emergency Go-Kit EFHW Calculator
Materials for Emergency Go-Kit Antenna
Building and Packing the Emergency Go-Kit Antenna
Build both components ahead of time and pack them together - the goal is a kit that's ready to grab, not something assembled for the first time during an activation.
Build the EFHW wire and unun
Cut the EFHW wire to length from the calculator above, and connect it to a 49:1 unun with a short counterpoise, following standard EFHW construction practice.
Build (or verify) your roll-up J-pole
Build the roll-up J-pole from the dedicated guide on this site if you don't already have one, and confirm it rolls compactly and deploys quickly.
Pre-cut and coil both feedlines
Cut coax feedlines to a practical length for each antenna and coil them neatly so they deploy without tangling under time pressure.
Assemble the throw line
Attach a small weight or bag to a length of paracord for getting the EFHW's far end up over a tree branch or other elevated support point.
Test the full kit at home before you need it
Deploy both antennas in your own yard, time the setup, and sweep SWR on both to confirm everything works and fits together as expected.
Pack everything into one waterproof bag
Consolidate both antennas, feedlines, throw line, and a compact analyzer into a single labeled, waterproof bag or pouch.
Re-check the kit on a schedule
Periodically re-deploy and test the kit - wire, connectors, and cordage degrade over time in storage, and a kit that hasn't been checked in a year is a liability, not an asset.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| EFHW won't tune cleanly on-scene | Counterpoise disconnected or wrong length | Check the counterpoise is actually connected and roughly the right length first | Reconnect/correct the counterpoise; this is the most common field issue with EFHW-style antennas |
| Setup is taking longer than planned | One specific step (usually the throw line) is slow, not the antennas themselves | Revisit home practice runs and time each step separately | Practice the slow step independently until it's fast and reliable |
| Gear doesn't work the same as it did at home | Storage degradation or a component shifted in the bag during transport | Inspect wire, connectors, and cordage for wear or damage | Repair or replace degraded parts; this is exactly why the periodic re-check step matters |
Is this one specific antenna design?
No - it's a paired system combining an EFHW for HF and a roll-up J-pole for VHF/UHF, chosen specifically for fast, reliable, low-support-infrastructure deployment.
Why not just bring a full-size dipole and mast?
You can, if you have the time, vehicle space, and site to support it - this kit exists for the far more common emergency-comms case where you have neither.
Does this kit work without any support structure at all?
It needs at least one elevated point for the EFHW (a tree, a mast, a building) and something to hang the J-pole from - genuinely support-free deployment isn't realistic for either antenna type.
How often should I check the kit?
At minimum once or twice a year, and after any storage in extreme heat, cold, or damp - wire, connectors, and cordage all degrade over time even when unused.
Can I substitute a different HF wire design?
Yes - a linked dipole or a random wire with a 9:1 unun, both already covered on this site, work as alternatives if you prefer their specific tradeoffs, though the EFHW's single-support deployment is what makes it the default pick here.
What about power for the radio itself?
Outside this guide's scope, but plan for it just as deliberately as the antenna - a battery or generator that doesn't depend on commercial power is just as essential to an emergency kit as the antenna is.