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ANTENNAS FOR 100 POUND DXPEDITIONS 2

2

55.00

56.82

13

Open

3.42

2

14.2

Par

3

2

50.00

52.27

12

Short

0.52

Short

0

Ser

No transmission lines specified No transformers specified No L Networks specified Ground type is Real, High-Accuracy --------------- MEDIA --------------No.

Cond.

Diel. Const.

(S/m) 1

0.001

5

Height

R Coord.

(in)

(in)

0

0

An alternative configuration would be 8 radials at 33 feet and 8 radials at 24 feet. The gain results for that configuration appear below.

Band 10 12 15 17 20

No radials -0.45 -0.78 -1.20 -1.59 -2.29

With 8@24-feet + 8@33 feet Gain Relative gain +0.79 +0.57 -0.20 +0.50 +0.43

+1.24 +1.35 +1.00 +2.09 +2.72

With 16@33-feet Relative Gain

Comparing both relative gains

+1.94 +1.40 -0.36 +1.65 +3.37

+0.70 +0.05 -1.36 -0.44 +0.65

Table 10 Comparing gains for the 16@33-feet and 8@24-feet + 8@33-feet configurations There are minor reductions in gain compared to the 33-feet+20-feet radial pattern above on 10m (0.19 dB), 12m (0.65 dB), and 17m (0.38 dB). Gains relative to the other configuration are found on 15m (0.18 dB), and 20m (1.28 dB). This new configuration still suffers on 10m and 20m compared to the 16 radials of 33 feet, but shows better performance on all other bands. Returning to the comparison with the original baseline, the antenna situated over very poor ground, the relative gains with these radials are somewhere between 1 dB for 15m to 2.72 dB for 20m. Again, this is achieved with less than 500 feet of very light wire. The question is posed again: what other mechanism increases the performance of an antenna system on five bands yet weighs under a pound? Adding radials beneath the Force-12 Sigma-5 brings its performance to near parity with the Buddipole vertical with four elevated radials. In fact, radial lengths can be selected which would provide performance from this vertical dipole exceeding that of the Buddipole. Ground-mounted radials are easier to install (though there are more of them) since we do not need to rig a system to elevate them. Finally, we get all the flexibility and coax weight savings of the multiple band antenna with this arrangement. If space is available to lay out these radials, a multi-band vertical dipole with radials is a strong contender.

211

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Antennas for 100 Pound DXpeditions - volume 1  

Computer-based antenna modeling and direct experience with lightweight portable antenna systems. Volume 1: Selected high band antennas [20-6...

Antennas for 100 Pound DXpeditions - volume 1  

Computer-based antenna modeling and direct experience with lightweight portable antenna systems. Volume 1: Selected high band antennas [20-6...

Profile for ne1rd
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