mirror of
https://codeberg.org/mclemens/qrz.is.git
synced 2024-11-20 05:56:09 -05:00
51 lines
2.0 KiB
Markdown
51 lines
2.0 KiB
Markdown
---
|
|
title: "Shortened 30m Dipole"
|
|
date: 2020-02-02T15:00:00+02:00
|
|
type: post
|
|
tags:
|
|
- Ham Radio
|
|
- Antenna
|
|
url: /30m-dipole/
|
|
---
|
|
|
|
# Why and what
|
|
|
|
This aricle describes the construction of a 9,50 m long dipole for the 30 m band (10.1 MHz to 10.15 MHz). It was designed to be mounted ca. 6m above ground inside an attic. The calculations were performed by OE1MEW with the help of [this antenna calculator](http://66pacific.com). To reduce the length of the ~15 m long dipole, a coil will be integrated into each side of the dipole.
|
|
|
|
The following diagram shows the dipole in theory:
|
|
|
|
|
|
|
|
# Bill of materials
|
|
|
|
* 1 feed point connector with PL socket or a 1:1 balun
|
|
* 2 isolators
|
|
* 2x 1 m antenna wire
|
|
* 2x ca. 4 m antenna wire
|
|
* 2 short pieces of 16 mm installation tubes
|
|
* several meters of 1.5 mm2 copper wire (e.g. out of NYM-J 3 x 1,5 cable)
|
|
|
|
# Construction
|
|
|
|
## Coils
|
|
|
|
Drill a hole into the 16 mm installation tube and stick a few centimeters of the 1.5 mm2 wire through it. Afterwards tightly wind the wire around it 37 times. After the 37th turn, drill a hole closely to the wire into the tube and stick the wire through it. It now should look like this:
|
|
|
|
|
|
|
|
Repeat this step to build a second coil.
|
|
|
|
## Assembly
|
|
|
|
Connect 1 m antenna wire to each side of the feed point connector (or the 1:1 balun). Now solder the ends of the antenna wires to one side of each coil. Use shrink tubing to make it water resistant. Solder the 4 m pieces of antenna wire to the other side of the coils. Both ends should then be terminated with isolatiors. A good start for tuning is a wire length of about 3,60 m between coil and isolator. Wrap around the remaining 40 cm for the tuning procedure.
|
|
|
|
The result should look like this:
|
|
|
|
|
|
|
|
# Result
|
|
|
|
The antenna ended up being 9,30 m long (including feed point, excluding isolators). The following photos show how nicely this antenna can be tuned:
|
|
|
|
|