Bugstick Mobile Whip
A Bugstick (or "bugcatcher"-style) mobile whip sits between the two HF mobile antennas already on this site: a large, air-wound loading coil like a Hamstick's, but big enough to give noticeably better efficiency, paired with a manual tap or rotary switch you set by hand for each band instead of the Hamstick's fixed single-band resonance or the Screwdriver's motorized continuous tuning. It's the antenna serious HF mobile operators reach for when they want more coil than a Hamstick offers without the cost and complexity of a screwdriver's motor and control head.
Three mobile-whip approaches, one loading problem
All three designs solve the same problem — a mobile whip is always electrically short on HF, so it needs a loading coil to cancel its capacitive reactance and resonate — but they solve it with different tradeoffs. The Hamstick-style whip uses a small, compact, single-band-resonant coil per antenna: cheapest and simplest, but the small coil size limits efficiency. The screwdriver antenna uses a motor to continuously vary the coil tap from the driver's seat: maximum flexibility, at real cost and mechanical complexity. The Bugstick sits in between: a single, physically larger air-wound coil with a manually set tap point or rotary switch, and a top whip section you can also adjust.
Bugstick: larger coil, manual tap per band, better efficiency, no motor
Screwdriver: motorized continuous tap, most flexible, most complex
Why a bigger coil is genuinely more efficient
A loading coil's unloaded Q — how little of your transmitter power it wastes as heat instead of passing on to be radiated — improves with a larger coil diameter and a lower turns-per-inch winding for a given inductance. A Hamstick's coil is necessarily compact to keep the whole antenna small and cheap; a bugcatcher-style coil is deliberately built larger specifically to improve that Q, which is the real, measurable reason these antennas outperform a Hamstick on the same band.
What the top whip and tap point actually do
Extending or shortening the whip section above the coil (and adjusting the tap point that engages more or less of the coil's turns) is how you retune the same physical antenna across multiple HF bands — the same loading-coil principle behind every design in this family, just with more coil to work with and a bigger effective adjustment range than a Hamstick's fixed per-band construction allows.
- Shorter whip, more turns engaged: lower bands (75m/40m).
- Longer whip, fewer turns engaged: higher bands (20m/17m and up).
Honest expectations for mobile HF in general
Even a well-built Bugstick is still a heavily loaded short vertical compared to a full-size HF antenna, and its efficiency depends as much on a good vehicle ground plane and mount as on the coil itself. Expect solid, workable mobile HF performance appropriate to a loaded whip's real limits, not full-size-antenna signal reports.
Installation options
- Trunk-lip or hatch mount: a common, no-drilling mounting option that still provides a reasonable local ground reference.
- Hitch-mount bracket: keeps the coil and whip clear of the vehicle body, popular for trucks and SUVs already carrying a hitch.
- Bumper or fender mount: works well where a solid metal mounting point close to the vehicle's body/ground plane is available.
| Band | Whip length above coil | Approx. turns engaged | Notes |
|---|---|---|---|
| 75m/80m | ~24-30 in | Most of the coil | Lowest band, needs the most inductance |
| 40m | ~36 in | ~2/3 of the coil | Common starting band for tap-point testing |
| 20m | ~48 in | ~1/3 of the coil | — |
| 10m/6m | ~60+ in | Coil bypassed or minimal turns | Least inductance needed |
| Coil dimensions (typical) | — | ~3 in diameter, 120-140 turns #14 AWG | Physically larger than a Hamstick's coil by design |
Bugstick Mobile Whip Loading Calculator
Materials for Bugstick Mobile Whip
Building the Bugstick Mobile Whip
Winding the coil is the bulk of the work; the tap switch and whip adjustment are what actually let you change bands afterward.
Prep the coil form and drill tap holes
Cut the PVC coil form to length and mark/drill tap holes at the turn counts your target bands need, sized for the wire plus a tap lead.
Wind the coil
Close-wind the #14 AWG magnet wire the full length of the form, pulling a loop through each drilled tap hole and soldering on a tap lead as you go.
Wire the tap leads to a rotary switch or clip set
Bring each tap lead to a labeled position on a rotary switch, or to a set of labeled alligator clips if you're not using a switch.
Assemble the base spring, coil, and whip in order
Build the stack as base spring/mount → coil form → adjustable whip section, with solid connections at both ends of the coil.
Mount to the vehicle
Install your chosen mount bracket (trunk-lip, hitch, or bumper) and attach the antenna assembly, keeping the coax jumper short.
Set the starting tap and whip length per band
Using the dimensions table, set the tap position and whip extension for your target band as a starting point.
Sweep SWR and fine-tune
Sweep SWR at the vehicle in its normal parked/operating position and adjust whip length first, then tap position, to bring resonance onto your target frequency.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| High SWR (3:1+) that won't come down on any tap | Poor vehicle ground plane, or a bad coil/mount connection | Check continuity from the mount through the coil to the whip base | Improve the mount's ground contact and re-check coil connections |
| Resonance is off from the expected tap/whip combination | Vehicle body and mount location affect the antenna's effective ground plane differently than the dimensions table assumes | Compare your actual mount location against the reference (trunk lip vs. hitch vs. bumper) | Treat the table as a starting point and re-tune tap/whip length for your specific vehicle and mount |
| Efficiency/reports seem no better than a Hamstick | Coil form diameter or winding is undersized relative to a genuine bugcatcher-style build | Compare your coil's physical diameter and turn count against the materials list | Rebuild with a larger-diameter form if the coil is closer to Hamstick scale than intended |
How is this different from the Hamstick-style whip already on this site?
The Hamstick uses a small, compact coil sized for a single fixed resonance per antenna — cheap and simple, but limited in efficiency by the coil's small size. This design uses a deliberately larger coil with a manual tap for better efficiency on the same bands.
How is this different from the screwdriver antenna already on this site?
The screwdriver motorizes the tap position for continuous, from-the-seat band changes. This design uses a manual tap or rotary switch instead — no motor, no control head, but you do need to reach the antenna to change bands.
Is the bigger coil really more efficient?
Yes, genuinely — coil Q improves with larger diameter and lower turns-per-inch for a given inductance, which is exactly why bugcatcher-style coils are built physically larger than a Hamstick's.
Do I need a good ground plane/mount?
Yes, as much as with any mobile HF whip — a solid metal mounting point with good electrical contact to the vehicle body matters as much as the coil itself for real-world performance.
Can one coil really cover several bands?
Yes, that's the point of the multiple tap points combined with an adjustable whip section — the same coil serves multiple bands by engaging more or fewer turns and adjusting whip length.
Do I need to retune every time I change bands?
Yes, unlike a screwdriver's from-the-seat adjustment, changing bands here means physically resetting the tap and whip length, then re-checking SWR — a real tradeoff for skipping the motor and control head.