EA4FSI
HF · ANTENNAS · SIMULATION

Sloping Vee 470

This article describes and simulates, using MMANA-GAL, a Sloping Vee antenna with 470-ohm resistive loads. The analysis focuses exclusively on the antenna input impedance and radiation patterns.

HF · SLOPING VEEMMANA-GAL
Sloping Vee 470
Sloping Vee 470
TypeResistively loaded Sloping Vee dipole
DesignN/A
Impedance235 Ω
SimulationMMANA-GAL
BandBroadband HF
Remarks: The design uses 470 Ω resistive loads and requires a 4:1 balun.
Download MMANA-GAL simulation fileSloping_Vee_470.maaDownload simulation report (PDF)Sloping_Vee_470_report.pdf

1. Antenna design and modelling.

In this Sloping Vee design, each arm is 12 m long and terminates in a 470 Ω resistive load connected to ground (Fig. 1). The mast must be at least 6 m high. A ladder-line transmission line with a suitable characteristic impedance should be used, together with a 4:1 balun. An antenna tuner is recommended, particularly for automatic link establishment (ALE) operation.

Sloping Vee antenna with 470 Ω resistive loads.
Fig. 1. Sloping Vee antenna with 470 Ω resistive loads.

Figure 2 shows the antenna modelled in MMANA-GAL.

MMANA-GAL model of the Sloping Vee antenna with 470 Ω resistive loads.
Fig. 2. MMANA-GAL model of the Sloping Vee antenna with 470 Ω resistive loads.

The feed point is located on the Z-axis, 6 m above ground. The two dipole arms extend from this point, forming a 30° angle bisected by the Y-axis. A 470 Ω resistive load is connected at the far end of each arm.

2. Simulation results.

This section presents the MMANA-GAL simulation results, including calculated standing-wave ratios (SWR) and radiation patterns at the frequencies studied.

2.1. Standing-wave ratio (SWR).

Figure 3 shows the calculated SWR referenced to 200 Ω, corresponding to a 50 Ω transmitter connected through a 4:1 impedance-transforming balun.

Calculated SWR referenced to 200 Ω.
Fig. 3. Calculated SWR referenced to 200 Ω.

Although the SWR is relatively low, the simulation indicates that an antenna tuner is still required.

2.2. Radiation patterns.

Figure 4 shows the simulated radiation patterns at frequencies from 2 to 10 MHz.

Simulated radiation patterns at 2, 4, 6, 8 and 10 MHz.
Fig. 4. Simulated radiation patterns at 2, 4, 6, 8 and 10 MHz.

Figure 5 shows the simulated radiation patterns at frequencies from 11 to 20 MHz.

Simulated radiation patterns at 11, 13.25, 15.5, 17.75 and 20 MHz.
Fig. 5. Simulated radiation patterns at 11, 13.25, 15.5, 17.75 and 20 MHz.

The antenna is directional, although its front-to-back ratio is relatively low. Maximum radiation occurs approximately along the bisector of the angle formed by the two arms. Losses occur throughout the operating band and become more pronounced at lower frequencies. Although the antenna has relatively low efficiency, it offers the advantage of a low SWR across the HF band.

The antenna is not recommended for near-vertical incidence skywave (NVIS) operation because of its low gain at lower frequencies.

ORIGINAL PUBLICATIONNOVEMBER 2008