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I believe my loop is too big on my Vector. When you read the original Avanti patent for the Sigma IV it suggests that increased gain can be had with a larger distance between the radial ends and the main radiator with a larger hoop. Extensive field testing an experimenting with the antenna in EZNEC+ are confirming the exact opposite!

Most of my work has been done perfecting an FM broadcast version of this antenna. It just so happens that it's radials are just over 1/4 wavelength with a 1/4 wave loop. Those radials are longer then the original Sigma and early Vector. I've been told the new Vector has radials that are longer then 1/4 wave. Bob85 has confirmed an increase in gain with the longer radials and is what I see at 98 MHz too.

I think we will find the new Vector has the right cone section and may be similar to Bob's 11 meter design. I question shortening the radiator from 7/8 wave to 3/4 wave on the new Vector because in field tests on 98 MHz .82 wave always shows the max gain. EZNEC+ however, does show the shorter radiator to give more gain. It also shows that the tighter the radials are to the main radiator, the higher the gain. This can present design problems at high power because the radials can arc over to the radiator if they are too close.

Henry has been kind enough to send me a model he made of the Vector in EZNEC+. I am new with working in this program and find building the model difficult. I am able to easily change any of the dimensions in the model to experiment. If anyone else out here works with EZNEC I would like to share this model with them in an effort to confirm the model is the most accurate representation of the basic Vector design.

<blockquote data-quote="Shockwave" data-source="post: 210242" data-attributes="member: 10882">I believe my loop is too big on my Vector. When you read the original Avanti patent for the Sigma IV it suggests that increased gain can be had with a larger distance between the radial ends and the main radiator with a larger hoop. Extensive field testing an experimenting with the antenna in EZNEC+ are confirming the exact opposite!Most of my work has been done perfecting an FM broadcast version of this antenna. It just so happens that it&#039;s radials are just over 1/4 wavelength with a 1/4 wave loop. Those radials are longer then the original Sigma and early Vector. I&#039;ve been told the new Vector has radials that are longer then 1/4 wave. Bob85 has confirmed an increase in gain with the longer radials and is what I see at 98 MHz too.I think we will find the new Vector has the right cone section and may be similar to Bob&#039;s 11 meter design. I question shortening the radiator from 7/8 wave to 3/4 wave on the new Vector because in field tests on 98 MHz .82 wave always shows the max gain. EZNEC+ however, does show the shorter radiator to give more gain. It also shows that the tighter the radials are to the main radiator, the higher the gain. This can present design problems at high power because the radials can arc over to the radiator if they are too close.Henry has been kind enough to send me a model he made of the Vector in EZNEC+. I am new with working in this program and find building the model difficult. I am able to easily change any of the dimensions in the model to experiment. If anyone else out here works with EZNEC I would like to share this model with them in an effort to confirm the model is the most accurate representation of the basic Vector design.</blockquote>

[QUOTE="Shockwave, post: 210242, member: 10882"] I believe my loop is too big on my Vector. When you read the original Avanti patent for the Sigma IV it suggests that increased gain can be had with a larger distance between the radial ends and the main radiator with a larger hoop. Extensive field testing an experimenting with the antenna in EZNEC+ are confirming the exact opposite! Most of my work has been done perfecting an FM broadcast version of this antenna. It just so happens that it's radials are just over 1/4 wavelength with a 1/4 wave loop. Those radials are longer then the original Sigma and early Vector. I've been told the new Vector has radials that are longer then 1/4 wave. Bob85 has confirmed an increase in gain with the longer radials and is what I see at 98 MHz too. I think we will find the new Vector has the right cone section and may be similar to Bob's 11 meter design. I question shortening the radiator from 7/8 wave to 3/4 wave on the new Vector because in field tests on 98 MHz .82 wave always shows the max gain. EZNEC+ however, does show the shorter radiator to give more gain. It also shows that the tighter the radials are to the main radiator, the higher the gain. This can present design problems at high power because the radials can arc over to the radiator if they are too close. Henry has been kind enough to send me a model he made of the Vector in EZNEC+. I am new with working in this program and find building the model difficult. I am able to easily change any of the dimensions in the model to experiment. If anyone else out here works with EZNEC I would like to share this model with them in an effort to confirm the model is the most accurate representation of the basic Vector design. [/QUOTE]

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