# A narrative report on CoP Antenna project

## Introduction

### Waveguide Antenna

Waveguides are basically a device ("a guide") for transporting electromagnetic energy from one region to another. Typically, waveguides are hollow metal tubes (often rectangular or circular in cross section). They are capable of directing power precisely to where it is needed, can handle large amounts of power and function as a high-pass filter.

waveguides are wideband devices which can carry power or communication signals,this waveguide has a cutoff frequency, fc.

The cutoff frequency is the frequency at which all lower frequencies are attenuated by the waveguide, and above the cutoff frequency all higher frequencies propagate within the waveguide. The cutoff frequency defines the high-pass filter characteristic of the waveguide: above this frequency, the waveguide passes power, below this frequency the waveguide attenuates or blocks power.

The cutoff frequency depends on the shape and size of the cross section of the waveguide. The larger the waveguide is, the lower the cutoff frequency for that waveguide is.

##### **Idea to Implementation**

the idea was to develop waveguide antenna locally
so we satrted to look at what sort of antenna to be designed based on the experience by alter mundi

we read documents published by alter mundi [https://tdr.libre.org.ar/blog/]

also researched on types of cables and connectors where to get them and cost

Readings about cantenna
* https://en.wikipedia.org/wiki/Cantenna
* http://www.wikarekare.org/Antenna/WaveguideCan.html

Understanding and calibrating litevna 64
http://nanovna.com/wp-content/uploads/2021/11/LiteVNA_User-Guide.pdf

building cantenna designs for waveguide propogation

Identifying the shops who sells lmr 200 cable in sp road bangalore and ordering

**figure: LMR-200**

for different designs

To follow altermundi design specs we bought SMA connectors
**figure: SMA-connectors**

and for making another antenna where we needed ntype connector depicted below **nType pig tail** connectors

## Antenna fabrication

followed this blog by Altermundi in designing antenna

https://tdr.libre.org.ar/blog/5-how-to-make-a-waveguide-antenna-description-of-our-workspace/


with the above design it was difficult to solder the mesh of wire on the cylinder **even with 1000 watts soldering gun** as the heat radiates on the cylinder and it becomes too diffult to solder and as alter mundi suggests we need to solder using fire torch based soldering gun or with induction based soldering gun as we didn't have that setup we chose to come up with alternate plan to use different type of connectors which can be easily plugged into the cylinder

some of the not successfull work done is shown with two images below

**figure: soldering failure 1**


**figure: soldering failure 2**


based on the above problem faced we decided to use **nType** connector which has mounting holes and soldering cup for soldering the copper receptor lead according to required size

### nType flange mount with soldercup

**figure: nType pig tail with solder cup**

**figure: nType pig tail** (another angle)


### nType mounted to cantena

### nType connected to lmr cable via sma adaptor

another problem type using ntype receptor is we need ntype to sma adaptor to connect it to lmr cable with sma adaptor

### cantena connected to litevna to test

there are several other types of
SMA Receptacle Female Socket flange mounting with solder cup connectors are available below are the images of them

#### using below connectors will avoid adaptor from ntype to sma ####

### 4 hole flange mount sma soldercup


### 2 hole flange mount sma soldercup

**SMB-M-S-BRM-SC_001**
SMB "SubMiniature B" connector series was designed as a smaller snap-on coupling replacement for the SMA connector.
smb male straight bulkhead rear mount connector solder

**Figure: SubMiniature B connector**

also we tried making one DIY wifi gun but didn't get successfull results.

reason for failure is mounting the wires precisely on these plates became too cumbersome as the distance between the first and second plate was too close and isolating the plates without shorting them on the mounting rod was difficult as distance between them was almost nil the space that was available was occupied by nuts to hold them these nuts should be isolated from one another but due to lack of available distance between them it was not possible to do so

**Figure: DIY wifi gun**
yagi antena gun model

## Next steps
Now that (Jan 2023), we have the design and prototyped versions of the antenna, our task of working with the community to build and tune antennas for their CN node needs can start. We are planning a workshop with interns from an engineering college in the coming weeks and after that we will invite the community to build their own antennas.