Ham Radio VHF Antenna Guide — 2m, 70cm & Beyond
VHF and UHF amateur bands offer a completely different operating experience from HF — primarily line-of-sight propagation, local FM and digital voice, occasional tropospheric ducting that suddenly opens contacts hundreds of kilometres away, and weak-signal SSB/CW operating that rewards high-gain Yagi antennas and low-noise receive systems. This guide covers every practical antenna choice for 2 m (144–146 MHz), 70 cm (430–440 MHz), and the adjacent VHF/UHF bands, with dimensions, installation guidance, and a universal element calculator.
At 144 MHz and above, the ionosphere is generally opaque to amateur signals during normal conditions — F2 and sporadic-E propagation occur on 2 m only during exceptional circumstances. The dominant propagation mode is geometric line-of-sight (LOS): signals travel in straight lines from antenna to antenna, limited by the radio horizon at approximately 4/3 of the optical horizon due to atmospheric refraction. The practical consequence is that antenna height is the most important single variable in VHF antenna performance — getting the antenna higher extends the radio horizon and reaches more distant stations.
Beyond line-of-sight, three additional propagation modes extend VHF range dramatically: tropospheric ducting (anomalous refraction in temperature inversions that can extend 2 m contacts to 2,000 km), aircraft scatter (reflections from passing aircraft, creating brief 5–30 second paths to otherwise unreachable locations), and meteor scatter (reflections from ionised meteor trails, used for contact distances of 1,500–2,200 km using digital modes like MSK144). Each of these modes has different antenna requirements — ducting rewards height and gain, meteor scatter rewards omnidirectional coverage or multiple beams, aircraft scatter rewards fast-response monitoring of specific flight paths.
Local FM and repeater operation
A vertical quarter-wave or collinear antenna at 3–10 m height. Omnidirectional coverage essential — you do not know which direction repeaters or simplex contacts are. Vertical polarisation is the convention for FM and digital voice. Gain helps reach distant repeaters but causes pattern distortion that reduces contacts from nearby stations.
Weak-signal SSB and CW
Horizontal Yagi antenna, 5–15 elements, on a rotator. Horizontal polarisation is the convention for weak-signal VHF. High gain (12–18 dBi) and low-noise preamplifier at the antenna are more important than transmit power. A 5-element 2 m Yagi at 10 m height with a good preamplifier beats a 100 W radio into a vertical for tropo contacts.
Contest and tropo DX
Maximum-gain antenna array — stacked Yagis or long-boom single Yagi (10–20+ elements), rotatable on an elevation mount for tropo ducting contacts. Elevation capability allows pointing the beam slightly above the horizon during ducting events, extracting maximum signal from elevated anomalous refraction layers.
Quarter-wave ground plane
The simplest VHF antenna — a single vertical element at λ/4 (51 mm on 2 m, 17 mm on 70 cm) above a set of three or four radials bent 45° downward to present approximately 50 Ω feed impedance. Gain is 0 dBi. Used as a reference antenna and for simple portable or fixed operations. Easy to build from aluminium rod or welding wire.
Collinear (vertical stacked dipoles)
Two or more half-wave elements stacked vertically and fed in phase, separated by phasing coils or matching sections. A 2-element collinear (J-pole or 5/8-wave GP) gives approximately 3–5 dBi gain over isotropic — equivalent to doubling transmitter power. A 4-element collinear (common in commercial base antennas) gives 7–9 dBi. The gain is concentrated in the horizontal plane at the expense of radiation toward low and high elevation angles — ideal for local and regional FM coverage from a fixed base station.
Yagi for VHF
A Yagi is the definitive weak-signal VHF antenna. On 2 m, a 5-element Yagi has approximately 10 dBi gain, a 9-element Yagi reaches 13 dBi, and a 15-element long-boom design approaches 16 dBi. The gain and directivity of a Yagi transform the operating experience on 2 m SSB — stations that are barely audible on a vertical suddenly become fully readable on a 9-element beam. The Yagi also concentrates received noise rejection in the pattern's null directions, improving signal-to-noise ratio beyond what the gain figure alone suggests.
J-pole and vertical sleeve dipole
The J-pole (see the dedicated J-pole build guide) is a popular vertical antenna for 2 m and 70 cm — easy to build from copper pipe, requires no radials, and provides 2.15 dBi gain. The coaxial sleeve dipole is a related design where the outer conductor of the coax forms the lower radiating element. Both are suitable for fixed omni-directional operation.
Key Dimensions for Common VHF Antennas| Antenna | Band | Element lengths | Gain | Feed Z |
|---|---|---|---|---|
| Quarter-wave GP (4 radials) | 2m (145 MHz) | Vertical: 510mm, Radials: 515mm each | 0 dBi | 50 Ohm |
| Quarter-wave GP (4 radials) | 70cm (433 MHz) | Vertical: 172mm, Radials: 173mm each | 0 dBi | 50 Ohm |
| Half-wave dipole | 2m (145 MHz) | Each arm: 490mm | 2.15 dBi | 70 Ohm |
| Half-wave dipole | 70cm (433 MHz) | Each arm: 163mm | 2.15 dBi | 70 Ohm |
| 5-element Yagi | 2m (144.3 MHz) | See DL6WU table — boom ~1.0m | ~10 dBi | 28 Ohm + match |
| 9-element Yagi | 2m (144.3 MHz) | DL6WU — boom ~2.0m | ~13 dBi | 28 Ohm + match |
| 5-element Yagi | 70cm (432 MHz) | DL6WU — boom ~340mm | ~10 dBi | 28 Ohm + match |
| Collinear 5/8 + 5/8 | 2m | Upper: 830mm, Lower: 720mm, phasing: 160mm | ~5 dBi | 50 Ohm |
VHF/UHF Antenna Element Length Calculator
Feedline loss matters far more at VHF than at HF because the loss per metre increases with frequency and antenna gains are higher — 3 dB of cable loss wipes out the entire gain of a 2-element Yagi. The following table shows insertion loss for a 10 m feedline run at typical VHF/UHF frequencies:
| Cable type | Loss / 10m at 145 MHz | Loss / 10m at 432 MHz | Loss / 10m at 1296 MHz | Verdict |
|---|---|---|---|---|
| RG-58 | 1.9 dB | 3.8 dB | 7.5 dB | Avoid for fixed VHF |
| RG-213 / LMR-240 | 1.0 dB | 2.0 dB | 4.2 dB | Acceptable for 2m |
| LMR-400 | 0.5 dB | 1.0 dB | 2.2 dB | Good — use for all VHF |
| LMR-600 | 0.3 dB | 0.6 dB | 1.3 dB | Excellent for long runs |
| 7/8" Heliax | 0.15 dB | 0.3 dB | 0.65 dB | Best for permanent install |
| Band | Frequency segment | Mode | Activity |
|---|---|---|---|
| 2m | 144.000–144.150 MHz | CW | Weak-signal CW, EME (144.000–144.025) |
| 2m | 144.150–144.400 MHz | SSB | Weak-signal SSB — 144.300 is the calling frequency |
| 2m | 144.174 MHz | FT8 | Digital weak-signal — most active 2m digital segment |
| 2m | 144.360 MHz | MSK144 | Meteor scatter digital mode |
| 2m | 144.600–144.800 MHz | FM simplex | Local simplex — 144.625 calling (UK) |
| 2m | 145.000–145.800 MHz | FM repeaters | Local repeater inputs/outputs |
| 70cm | 432.000–432.150 MHz | CW | Weak-signal CW, EME |
| 70cm | 432.150–432.500 MHz | SSB | Weak-signal SSB — 432.200 calling |
| 70cm | 432.174 MHz | FT8 | 70cm digital weak-signal |
| 70cm | 433.400–434.600 MHz | FM | FM simplex and repeaters |
Two identical Yagis fed with equal-length cables through a power splitter, mounted the optimum distance apart, provide approximately 3 dB more gain than a single Yagi plus a small additional improvement from the reduced side-lobe level. The optimum stacking distance is approximately λ/2 at the free-space wavelength — for 2 m Yagis this is about 1.03 m vertical separation. Four Yagis (2 × 2 horizontal and vertical stacking) give approximately 6 dB more than a single Yagi, approaching the effective gain of a single antenna with four times the boom length.
The power splitter for stacking must provide equal impedance to both antennas. A simple T-connector from two equal-length coax runs works if both antennas are identical — each presents 50 Ω, two in parallel gives 25 Ω which is then matched to 50 Ω by a short section of 35 Ω coax (λ/4 transformer) or by a commercial power divider. Pre-made HB9CV-style stacking harnesses are available commercially for 2 m and 70 cm Yagi stacking.
Frequently Asked QuestionsShould I use horizontal or vertical polarisation on 2m?
For FM, repeater, and digital voice operation use vertical polarisation — all FM antennas and handheld radios use vertical. For weak-signal SSB, CW, FT8, meteor scatter, and EME use horizontal polarisation — the convention is universal worldwide for weak-signal VHF. Cross-polarisation loss between horizontal and vertical is approximately 20 dB — you lose this if you try to work a weak-signal station with a vertical antenna.
How much does height matter at VHF?
Enormously. The radio horizon distance is approximately 3.57 × sqrt(height in metres) km. At 5 m height the horizon is 8 km; at 20 m height it is 16 km; at 50 m height it is 25 km. For FM simplex, going from 5 m to 20 m height extends your reliable range by 100% — equivalent to increasing transmitter power by 100×. For tropo DX, the antenna must be above local obstructions — even 10 m extra height can be the difference between working a distant station and not hearing them at all.
What is tropospheric ducting and how do I know when it is happening?
Tropospheric ducting occurs when a temperature inversion in the lower atmosphere traps VHF/UHF signals in a horizontal layer, allowing them to travel hundreds to thousands of kilometres with very low loss. On 2 m, you know ducting is occurring when: distant FM stations begin to appear on the FM broadcast band (88–108 MHz), 2 m beacons hundreds of kilometres away become audible, or when wsprnet.org shows WSPR spots on 2 m from very distant stations. Ducting is most common in summer evenings and during anticyclonic (high pressure) weather, particularly near coasts and bodies of water.
Can I use my HF beam antenna for 2m?
Not directly — HF beam antennas are far too large and resonant at the wrong frequencies for 2 m. A 40 m Yagi is approximately 50× too large for 2 m. However, a single HF antenna mast already in place at height can be used to support a 2 m Yagi mounted at the top — using the same mast and rotator infrastructure for both HF and VHF antennas is a common and practical arrangement.
What is the minimum antenna for a useful 2m SSB station?
A 5-element Yagi at 10 m height with a mast-head preamplifier is the practical minimum for useful 2 m SSB DX operation. This combination provides approximately 10 dBi gain and a receive noise figure below 1 dB — enough to work stations 300–600 km away during normal conditions and much further during tropospheric enhancements. A 9-element Yagi significantly improves the situation; beyond 12 elements the gains are real but diminishing for a typical UK or European location.
Does 70cm behave differently from 2m for propagation?
Yes — 70 cm (432 MHz) is slightly more line-of-sight dependent than 2 m. Tropospheric ducting occurs less frequently and over shorter distances on 70 cm than on 2 m, though it still happens. Aircraft scatter is proportionally more useful on 70 cm due to the shorter wavelength giving more reflection from aircraft fuselages. EME is active on 70 cm but requires larger antennas than 2 m for the same system gain. The smaller antenna dimensions on 70 cm make it very practical to build high-gain Yagis that fit on a light mast.