Cobweb (5-Band) Antenna
The Cobweb packs five folded dipoles — 20m, 17m, 15m, 12m, and 10m — onto a single roughly 2m-square frame, fed from one coax at the center. Each dipole is bent back and forth across the frame's spreader arms in the zigzag routing that gives the design its name, rather than running straight out to full half-wave tip spacing. Credited to Steve Webb, G3TPW, and widely published through RSGB, it's become a go-to compact HF antenna for small lots, tight HOA situations, and anyone who wants five-band coverage without five dipoles' worth of yard space.
Folded dipoles bent to fit, not shortened electrically
Each band's element is a full electrical folded dipole — it isn't shortened or loaded the way a trap or mobile whip antenna is. Instead, the wire is bent into a zigzag path across the frame's spreader arms so the full half-wave length fits inside a footprint far smaller than the wire's own tip-to-tip span would normally need. That's the entire trick behind the compact size: routing, not electrical shortening.
Why five elements can share one feedpoint without traps
All five folded dipoles land at the same center feedpoint, wired in parallel, with no traps or switches involved. On any given band, that band's element is close to resonance and presents a reasonable impedance at the feed; the other four elements are well off resonance at that frequency and present a high, mostly reactive impedance, so they load the active element only lightly. This is the same "off-resonance elements stay out of the way" principle that makes fan dipoles work.
17m/15m/12m/10m elements far off resonance (high Z, light loading only)
Performance expectations — compact, not a beam
Despite the crossed, web-like layout, the Cobweb is not a directional gain antenna the way a Yagi or Quagi is. Expect performance broadly comparable to a dipole at the same height on each band, with a mild pattern skew from the folded element geometry rather than meaningful forward gain. The real selling point is the footprint, not extra signal.
Why this differs from a fan dipole or trap dipole
A fan dipole uses the same parallel-elements-at-one-feedpoint principle but with straight, full-span wires needing real yard length per band. A trap dipole uses fewer physical wires but adds trap loss and complexity. The Cobweb trades a small amount of build complexity (bending five elements precisely) for a dramatically smaller footprint than a fan dipole, with no trap loss at all.
Installation options
- Rooftop or chimney mount, horizontal: the most common install — a short mast clamped to a chimney bracket or roof mount, keeping the frame level and reasonably clear of the roofline.
- Tripod on a balcony or small deck: a popular option for apartment and small-lot installs, since the frame's footprint fits where a full-size dipole farm wouldn't.
- Tower or mast-top mount: where a mast or tower is available, mounting the Cobweb at the top gives it clearance from nearby structures and improves consistency across all five bands.
| Band | Design freq (MHz) | Folded element span | Notes |
|---|---|---|---|
| 20m | 14.15 | ~33.1 ft (10.1 m) | Longest element; needs the tightest zigzag routing on the frame |
| 17m | 18.10 | ~25.9 ft (7.9 m) | — |
| 15m | 21.20 | ~22.1 ft (6.7 m) | — |
| 12m | 24.94 | ~18.8 ft (5.7 m) | — |
| 10m | 28.50 | ~16.4 ft (5.0 m) | Shortest element; easiest to route on the frame |
| Frame (X-spreader) | — | ~2.1 m per arm | Fiberglass or wood spreader arms, non-conductive |
Cobweb 5-Band Element Length Calculator
Materials for Cobweb 5-Band Antenna
Building the Cobweb 5-Band Antenna
Building the frame is straightforward; routing five wires accurately across it in the correct zigzag pattern is where the real care goes.
Build the spreader frame
Assemble four fiberglass or wood spreader arms into an X (or box) shape around a center hub, roughly 2m x 2m overall.
Mount standoff insulators along each arm
Install standoff insulators at the points where each band's zigzag wire run needs to turn, working from your dimension plan for all five elements.
Cut and route the 20m element first
Cut the longest (20m) folded dipole pair to length from the calculator, and route it in its zigzag path across the outermost standoffs, since it needs the most frame perimeter.
Route the remaining four elements, longest to shortest
Continue with 17m, 15m, 12m, then 10m, routing each progressively shorter element on standoffs closer to the frame's center.
Connect all five elements at the center feedpoint
Land all five folded dipoles' feedpoints in parallel at the center bracket, install the choke balun, and connect the SO-239.
Mount the frame horizontally
Attach the assembled frame to a mast or tripod mount, keeping it level and clear of nearby metal structures.
Connect coax and weatherproof
Run the coax feedline down to your station and seal the feedpoint connections against moisture.
Sweep each band and trim as needed
Check SWR on each of the five bands in turn. Because the elements are independent folded dipoles, trim only the element for the band that's off — the others shouldn't need adjustment.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| One band is off, but the others are fine | Each band is an independent folded dipole in parallel at the shared feedpoint | Confirm only one element's SWR is affected | Trim only the affected element's length; the others shouldn't need adjustment |
| All bands read high SWR | Shared fault at the common center feedpoint or choke balun | Check center feedpoint connections and the choke balun first | Re-solder or repair the shared feedpoint connection or balun |
| Elements are shorting against each other | Two different bands' zigzag runs touching where they cross on the frame | Inspect every point where two elements' runs cross near each other | Separate the wires at the contact point and re-check spacing along the whole run |
Is the Cobweb a gain/beam antenna?
No — despite the web-like layout, it performs roughly like a dipole per band, with a mild pattern skew from the folded geometry. Its advantage is footprint, not gain.
Do I need traps or a band switch?
No — all five elements are independent folded dipoles wired in parallel at one feedpoint. No traps, and no switching is required.
Can I rotate it for a favored direction?
You can, and some builders do mount it on a light rotator, but since the pattern is close to omnidirectional per band, the benefit is modest compared to rotating a true beam like a Yagi.
How much yard space does this really save?
A full-size 20m dipole alone needs about 33 ft of clear span; the Cobweb fits all five of its bands, including 20m, onto a roughly 2m-square frame — a dramatic footprint reduction for HOA and small-lot situations.
Can I add or substitute bands?
The classic design covers 20m/17m/15m/12m/10m. Substituting a different band means recalculating that element's folded length and re-routing its zigzag path on the frame — it isn't a drop-in swap.
Why folded dipoles instead of plain dipole elements?
The folded configuration gives a wider bandwidth and a feed impedance that's easier to bring five separate elements together at one shared feedpoint without excessive interaction, compared to plain single-wire dipole elements.