3 Antennas Compared

Recently we discussed the comparative performance of 3 wire antennas, sized for 80 m, on 3.5 MHz and above. I used antenna modeling to compare the following antennas, all at 40 ft above rocky ground:

• W8JI 110 ft dipole
• Horizontal Loop of 287 ft
• 133 ft Off-Center Fed Dipole

I found that the shapes of the radiation patterns vary, but the peak total gain figures are similar among the 3 for the two frequencies I used: 3.5 and 7.2 MHz. Here is a summary of results:

	Maximum Total Gain (dB)
	@ 3.5 MHz	@7.2 MHz
110 ft dipole	5.53	6.59
Horizontal Loop of 287 ft	6.39	5.83
133 ft OCF Dipole	5.74	6.42

Radiation patterns for the 2 frequencies are shown in this PDF file. If you zoom in enough you can read the data on each graph.  Patterns for additional frequencies are easily generated.

I used a similar side-by-side presentation in this 2010 posting when comparing two antennas sized for 160 m (110 ft or 130 ft wire to each side of the feed point).

WA5MLF

Antenna Wire Candidates

W4BXI recently shared some samples of antenna wire candidates for review and discussion. I've stripped back the tough insulation on the telco wire types to reveal the conductors and check their wire gauge. Below are photos of the samples, with captions. Click on any photo to magnify.

This first photo shows two similar drop wire types, both with copper-clad steel conductors. Telco #1 appears to be 16 ga, based on my adjustable wire stripper. Telco #2 is 19 ga, based on measurement with a telco wire gauge that has calibrated openings for 19, 22, 24, and 26 ga. The insulation is tough, but manageable with a sharp knife. The copper cladding still looked like copper after my scraping with a knife.


This photo shows two identical or very similar drop wire samples. Both have 2 pairs of 24 ga copper wire. Non-metallic (probably Kevlar) strength members are located near the outside edges of the outer jacket. The wires are located between the strength members. The outer jacket insulation is very similar to the that of the first two samples.


This last photo shows two types of single-conductor stranded wire. #4 has 7 strands of 24-ga bare copper, THHN insulation that is resistant to gasoline & oil. #5 has many strands of tinned copper wire.