Four-Square vs Half-Square Antennas: An Honest Deep Dive
Four-Square vs Half-Square Antennas: An Honest Deep Dive
Among serious HF DXers, the Four-Square phased vertical array and the Half-Square are two of the most effective low-angle antennas. Both can put your signal right into the long‑haul DX window at single‑digit degrees. Below is the engineering context—angles, gain, ground dependency, bandwidth, and complexity—so you can choose the right tool for your station.
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The Four-Square: Precision Through Phasing
A Four‑Square uses four λ/4 verticals on ~0.25λ spacing, fed via a phasing network (hybrid coupler + switching) to steer the main lobe in four directions. Mutual coupling and phase control compress the lobe and push it very low.
| Parameter | Typical Four‑Square |
|---|---|
| DX Peak Angle (20 m / 40 m) | ~4–6° / ~7–9° (average ground, well‑tuned) |
| Forward Gain | ~5–6 dB over a single λ/4 vertical (band‑dependent) |
| Front‑to‑Back (F/B) | ~20–25 dB with good symmetry and ground |
| Usable Bandwidth | ~3–4% of f0 without retuning (element Q + hybrid) |
| Ground System | Heavy: 30–60 radials per element recommended |
| Complexity | High: phasing box, relays, hybrids, matched lines |
Strengths: switchable headings, higher gain, deep nulls for noise/QRM rejection.
Trade‑offs: space, cost, precise build symmetry, and strong dependence on soil and radials.
The Half-Square: Simplicity with the Same DX Angles
The Half‑Square is a naturally phased, two‑element vertical dipole array: two ~λ/4 vertical legs joined by a ~λ/2 top wire. The top wire sets the phase relationship—no hybrid required—yielding a single, low‑angle lobe broadside to the horizontal wire.
| Parameter | Typical Half‑Square |
|---|---|
| DX Peak Angle (20 m / 40 m) | ~4–6° / ~8–10° (average ground, proper height) |
| Forward Gain | ~3.5–4 dB over a dipole at similar height |
| Front‑to‑Back (F/B) | ~10–15 dB typical |
| Usable Bandwidth | ~5–7% of f0 (dipole‑like behavior) |
| Ground System | None (balanced): only a good current choke at feed |
| Complexity | Low: two high supports + coax feed (with choke) |
Strengths: single‑digit DX angles rivaling a 4‑Square, minimal ground demands, simple build.
Trade‑offs: fixed broadside heading (without mechanical re‑rigging), modest F/B vs 4‑Square.
Practical Comparison
- Low‑Angle Launch: Both deliver the coveted single‑digit DX angles on 20 m and 40 m when properly implemented.
- Gain: The 4‑Square typically adds ~2 dB more forward punch and deeper nulls—great for contesting and targeted noise rejection.
- Bandwidth & Tuning: Half‑Squares are forgiving; 4‑Squares are narrower and benefit from meticulous element/Q matching.
- Soil/Radials Sensitivity: 4‑Squares live and die by the ground system. Half‑Squares are largely independent of soil loss.
- Complexity & Maintenance: Phasing networks, relays, and equalized line lengths raise the bar for 4‑Squares; Half‑Squares stay simple.
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Bottom Line
If you need switchable headings, maximum nulls, and can commit to the radials and symmetry, the Four‑Square is the contest‑grade choice. If you want nearly the same DX launch angle with far less complexity and cost, the Half‑Square is the 90%‑performance, 10%‑hassle solution—especially compelling on 20 m and 40 m.
Mini-FAQ
- Which has the lower angle on 20 m? — Both can peak around ~4–6° when properly built.
- And on 40 m? — Four‑Square ~7–9°; Half‑Square ~8–10° (site‑dependent).
- Which is easier to install? — The Half‑Square: two tall supports and a good current choke.
- Do I need radials? — Four‑Square: yes, many. Half‑Square: no (it’s balanced).
- Which has more gain and deeper nulls? — The Four‑Square by ~2 dB with stronger F/B when optimized.
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