¼-Wavelength Vertical Monopole for the 2 m Band

Summary

MMANA-GAL simulation of a 1/4-wavelength vertical monopole designed for a centre frequency of 146 MHz. Results are presented for standing wave ratio, radiation pattern and antenna input impedance.

Originally published on 10/12/2009.

Type	Monopole
Design	REMER
Impedance	58 + j17 Ω
Modelling	MMANA-GAL
Band	2 metres
Notes	4 radials arranged at 45 degrees. Simulation at 7 metres above perfect ground.

Download MMANA-GAL model fileVHF - Dipolo L4 146 MHz radiales a 45º.maa Simulation report (Z, SWR, Gain)monopoloL4_report.pdf

1. Antenna design

The antenna is made of a quarter-wavelength monopole for 146 MHz, plus a ground plane made of 4 radials separated 90 degrees between them and bent 45 degrees from the monopole.

**Fig.1.** 1/4 wavelength monopole (Vademecum REMER)

Monopole modelled in MMANA-GAL — **Fig.2.** 1/4 wavelength monopole modelled in MMANA-GAL

2. Standing wave ratio (SWR)

**Fig.3.** SWR of the monopole simulated in MMANA-GAL

Fig.3 shows the SWR calculations for a characteristic impedance of 50 ohms. The SWR at the central frequency (146 MHz) is 1.4.

3. Radiation pattern

**Fig.4.** Radiation pattern of the monopole simulated in MMANA-GAL

Fig.4 shows the radiation pattern resulting from the simulation. The antenna is omnidirectional and has a gain of 7.91 dBi.

4. Input impedance

**Fig.5.** Input impedance of the monopole simulated in MMANA-GAL

Fig.5 shows the input impedance of the antenna, computed with MMANA-GAL between 144 MHz and 148 MHz. The input antenna impedance at the central design frequency (146 MHz) is 58 + j17 ohms.