SP3L's Antennas - CEMs - Converging-Element Monopoles

CEMs - Converging-Element Monopoles

CEMs are based upon CEDs in which one half of the antenna is removed and replaced with a ground connection. In the model, the ground connection is approximated with a system of 16 radials 3.5 m long, lifted 0.01 m above the ground. If you have a NEC-4/5 based simulator, you may model buried radials. When I was simulating these antennas, I had access to NEC-2 only.

The broadband verticals are compared to a quarter-wave monopole (maximum gain of -0.12 dBi when simulated over average ground).

3-element CEM

This antenna performs a little better than 2-element BMA and seems to be simpler in construction. Its azimuthal radiation pattern is practically omnidirectional, the difference between X and Y gain is of the order of 0.1 dB only.

Click here to download this antenna models. Please note that the MMANA-GAL model does not have radials over the ground but a direct connection to the Mininec ground.

5-element CEM

This antenna is a little more complex. but has lower SWR and better gain than the ones described above. It is perfectly omnidirectional.

Click here to download this antenna models. Please note that the MMANA-GAL model does not have radials over the ground but a direct connection to the Mininec ground.

5-element CEM XF

This is a modification to the basic 5-element CEM extending its frequency range to 10.1 - 29.7 MHz. This antenna covers 6 amateur bands!

Click here to download this antenna models. Please note that the MMANA-GAL model does not have radials over the ground but a direct connection to the Mininec ground.