Questions tagged [radiation-pattern]

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Can fanned/parallel endfed antennas be used to get higher gain in some directions?

I have two pieces of antenna wire which are roughly 10 m long, with banana plugs at the ends, which I bring to hang in the trees when operating portable. I also bring a 49:1 unun and hopes that my ...
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what is main reason for formation of side lobes in directional antennas?

I would like to know why are side lobes formed along with main beam in an antenna. I asked one of my colleague and he explained me that its due to radiation of frequencies near to the required center ...
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Total radiation pattern in antenna arrays

let's consider a simple linear uniform spaced array: We know that, from elementary array theory, the total pattern (for instance in terms of E-field) may be evaluated, in case no phase shift is ...
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Half wave dipole with parasitic element, (Gain calculation)

good morning all, I have difficulties to find the correct formula that allows me to calculate the gain of half wave dipole in parallel with another parasitic half wave dipole. I'm trying to calculate ...
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How Does the Performance of an Inverted V Dipole Compare to a Linear Dipole?

The NEC4.2 comparison in the answer below shows one example, for a practical set of installation conditions.
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How Much Does the Radiation Pattern of an "EFHW" Antenna System Vary Across its Bands?

This NEC4.2 analysis shows one example of such variation.
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Do the Horizontal Conductors of a Ground Plane Antenna Adequately Decouple Its Feedline?

A NEC4.2 analysis of this configuration may reveal an unexpected truth about this...
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What Are Some of the Most Important Characteristics Applying to the Radiation of Monopole Antenna Systems?

Such characteristics are described in Answer 1 below, as sourced in a study of antenna engineering textbooks, and by generating NEC4.2 studies.
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Do Far-Field Radiation Patterns/Gains of NEC Software Accurately and Always Show the E-M Fields "Launched" by Vertical Monopoles?

Judging from posts on the Internet, this belief commonly is considered to be valid. But what is the correct answer?
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Need help understanding the gain on antenna pattern plots

My understanding is that the value of the axis (like -10 / 0 dB) refers to the maximum antenna gain (e.g. 12dbi). So, if a ...
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Understand Radio Pattern of a WIFI antenna

I have a Fortigate AP, and need to understand its radio pattern for optimal positioning. I've already understood the E-plane and H-plane representations and also that number on the circumference of ...
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2 answers
217 views

How to plot transmitter coverage area?

As an Extra class licensee, I should probably know this... I am working on a web application for repeater owners. I would like to include an estimated coverage area, provided they have entered all of ...
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What are the effects of a ground plane under a horizontal dipole?

What are the effects on signal propagation if this ground plane is just a metal object and what are the effects if the ground plane is actually grounded? I am asking this question because someone ...
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4 answers
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Ham operators often tell me that comparing gain to an isotropic radiator isn't much use because it's only a theoretical antenna, is this true?

When you look down on an isotropic radiator from above, ie : the azimuth view radiation pattern, it's a circle. The same as looking down on any omni directional antenna. So when comparing the gain of ...
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8 votes
2 answers
725 views

How to derive antenna gain from radiation pattern

I need to calculate the antenna gain in both dimensions: azimuth and elevation. The datasheet of the antennas I am using has two different radiation patterns, one for the elevation and one for the ...
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1 answer
454 views

Dipole antenna radiation field equation

Can anybody provide me with an idealised formula that describes the radiation pattern of an omnidirectional dipole antenna? In particular I am interested in the formula that creates a plot similar to ...
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2 answers
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How Does the Low-Angle Radiation of a Horizontal Dipole Compare to That of a Vertical Monopole?

Conventional wisdom based on the far-field (only) patterns calculated by M-o-M software such as NEC show that low-angle radiation from a horizontal dipole is very low, and zero in the horizontal plane....
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3 votes
1 answer
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Antenna Patterns and Multipath Effect

It's said that in order to decrease multi-path effects on receiving antennas that your antenna pattern should have a sharp slope near the horizon. Why? for example this is article mentioned it.(...
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2 votes
1 answer
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How Might Nearby Re-Radiators Affect the Radiation Patterns of a Transmit Antenna?

Here is one example of such, based on a NEC study...
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What is the easiest way to eliminate a beam antenna's backward radiation (rear lobe)?

I tried a metallic reflector which works well in terms of radiation, but considerably degrades the return loss and adds more complexity to the design.
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2 answers
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Antenna Q vs pattern shape

Is there any reason to think that changing the Q of an antenna would affect the directional pattern, assuming that is the only variable that changes? Restricting to values of Q say less than 1000. ...
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1 vote
3 answers
241 views

How to calculate/estimate the effect of having conductive material nearby an antenna

I have a system with a 1/4 wave whip antenna and above the antenna there is a mess of aluminium they're not connected but are nearby. I would like to figure out what effect this would have on the ...
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1 answer
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Directional antenna overlapping main lobes

In a 2-Rx by 2-Tx directional antenna system, say both transmitters are transmitting concurrently as in Fig. The main lobes from the two transmitters overlap. How does this affect the resultant signal ...
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8 votes
1 answer
791 views

Phased Array Pattern

I'm working on a passively scanned phased array radar project, as a concept and hopefully design. One of the things that bugs me is that antenna patterning used. The vast majority of radar arrays I'...
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2 votes
1 answer
260 views

Would a covering like aluminised kapton effect antenna radiation pattern?

I'm looking at using a 1/4 wave whip antenna for a transmitter. If possible I'd like to cover the antenna in very thin (0.02 mm) aluminised kapton for reasons unrelated to the radio system; to be ...
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2 votes
1 answer
895 views

Horizontal dipole radiation gaps

Consider the radiation pattern of a horizontal dipole mounted at a height of 1.75λ. Is it possible for a receiving station's antenna to be mounted at a certain height such that the radiation of the ...
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3 answers
315 views

Can you place reflective material near to an antenna without interfering with the radiation pattern?

So I'm trying to understand how radiation pattern are calculated and it's going well (so far!). I've come across a bit of an issue when it comes to the following situation: If we have a ...
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3 votes
1 answer
244 views

Rhombic Polarization Question, provided radiation maps

I am trying to engineer my first antenna to get on the air. I need to hit a repeater 50 miles away at a lower elevation than me so that I can use its IRLP nodes. Would this mean I am looking for low ...
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3 votes
1 answer
85 views

What's the general difference between radiation patterns of stationary and adaptive aerials in mobile communication systems?

I am trying to find general difference between radiation patterns of adaptive and stationary antennas (common difference, calculation difference and any other). I am interesting in any example and ...
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2 votes
1 answer
1k views

Radiation pattern for a 1/4th wave 2 meter antenna used on 70cm

What would the radiation pattern look like if I used a 1/4th wave 2 meter mag-mount antenna on 70cm with an HT.
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