Tuesday, May 9, 2017

Comparing the performance of an inverted vee dipole with a small transmitting loop on 40m. Post. #1126.

Comparing the performance of an inverted vee dipole with a small transmitting loop on 40m
(http://www.sotabeams.co.uk/blog/comparing-the-performance-of-an-inverted-vee-dipole-with-a-small-transmitting-loop-on-40m/).
Accessed on 09 May 2017, 19:15 hrs, UTC.
Author:  Richard Newstead.
Please click link to read the full article.

Comment:

Have you ever questioned the efficiency and ease of operation of the antenna you use for portable operations, such as SOTA, IOTA, and Field Day activities? Radio amateurs certainly have a wide selection of antennas available for such activities, ranging from homemade dipoles to commercially made verticals and magnetic loops.

In this expertly written essay, Richard Newstead compares two popular antenna systems:  an inverted vee dipole and a small transmitting loop called the "Chameleon P-Loop."

In "carefully controlled conditions", Richard puts each antenna through a series of transmitter tests, reception reports, and performance parameters to determine the efficiency and effectiveness of each antenna.  He supplies graphs, photos, and other data to underline his methodology.

While both antennas performed well with WSPRite low powered transmitters (about 200 mW output), the inverted vee dipole proved to be the more efficient antenna during these tests.

Here are Richard's conclusions:


The antenna configurations tested are typical of a SOTA deployment, and the experimental results suggest that the Inverted V antenna is about 15 dB better performance than the P-Loop antenna as tested.

NEC models suggest that the radiation efficiency of the Inverted V is around 42% or -3.8dB, and the P-Loop would appear to be about 15dB lower at -18.8dB or 1.3%.

No practical HF antenna is 100% efficient, the important outcome of this experiment is that you can expect the Inverted V to be around 15dB better than the P-Loop in similar situations.
The loop efficiency will improve on higher frequencies.
Addendum: 
1. The manufacturer of the P-loop gives a calculated efficiency of 5.674% at 7150 kHz. The calculation method is not shown.
2. The comparison above has not been normalized to account for the small differences in feeder losses as it was designed primarily to be a system-level comparison for typical portable configurations.

With thanks for helpful suggestions from Owen Duffy (9-May-17)

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Aloha es 73 de Russ (KH6JRM)