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93 views

### 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 ...
63 views

### 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 ...
101 views

### 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 ...
249 views

### 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.
126 views

### 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.
140 views

56 views

### 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.
139 views

### 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?
118 views

### 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 ...
74 views

### 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 ...
174 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 ...
414 views

### 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 ...
158 views

### 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 ...
608 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 ...
403 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 ...
133 views

### 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....
95 views

### 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.(...
67 views

### How Might Nearby Re-Radiators Affect the Radiation Patterns of a Transmit Antenna?

Here is one example of such, based on a NEC study...
501 views

### 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.
88 views

### 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. ...
234 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 ...
116 views

### 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 ...
689 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'...
205 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 ...
779 views

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 ...
298 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 ...
240 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 ...