# Inverted F Type Antenna Design for the Cattle Activity and
## 2 Antenna Design and Installation  
On the left side of Figure 1, a movement sensor module and mainboard in the form of a livestock necklace is mounted on the belt and installed on the neck of the livestock. The mainboard (58 \(\times\) 68 mm), sensor, and RF module are shown in the center of Figure 1. On the right side of Figure 1, the necklace on which the sensor module is mounted is hung around the neck of the animal. The gyro sensor on the mainboard detects the movement of livestock, and the mainboard transmits the movement data to the base station through the ZigBee RF transmission and reception module with a monopole or high-gain patch antenna based on the size of the ranch. The ZigBee HbeePro-20C RF module (red dotted line box in Figure 1) for general development has a ceramic chip antenna for short range such as 1 m transmission and reception, and the return loss of the antenna is quite bad for use over a long distance (10-100 m) such as in a ranch as an antenna. Therefore, the antenna for the RF module should be developed in consideration of the size of the case, the size of the mainboard, the size of the RF module, and the location of the antenna feeding point.  
In the base station, wireless sensor data of all livestock are collected, and it is possible to predict and manage the health status of livestock and various livestock-related data based on the collected data. The low 8 kb/s data can be analyzed and displayed by a mobile or computer, and the result can be informed in advance to the owner. Daily or weekly data collected continuously and analysis of the data makes it possible to predict the future and various outcomes such as health status, breeding period, and activity status of cattle.  
Figure 2 shows the RF transmission/reception module and a small chip antenna for short-distance communication installed on the top of the RF module. The chip antenna is connected to the feeding point of the PCB of the RF module. The size of the RF module is about 20 \(\times\) 25 mm, and the size of the feeding point is 4.4 \(\times\) 1.5 mm, as shown in Figure 2. The left side of the feeding point is + and the right side is ground. The distance between the feeding point and ground is fixed as 2-2.4 mm as shown in Figure 2 and the ground. Therefore, the feeding position, size, and relative location of the +/ - location are fixed.  
The general structure of an IFA antenna is shown in Figure 3 [11]. The IFA antenna is similar to a bent mono-pole antenna parallel to a ground plane used in wireless communication. A bent monopole antenna is fed from an intermediate point a distance from the grounded end. The design has some advantages over a simple monopole: the height of the antenna is shorter than the equivalent monopole and more compact. The impedance matching is easier, controlled by changing the distance between the feed line and ground position, and does not require any other extra matching components. The summation of  
Figure 1: Cattle necklace-shaped sensor board and case.  
part of the RF module, as shown in Figure 4. The antenna starts from the feeding point, which is the right-top of the RF module, and it extends straight out to the left side of the RF module. Since the size of the RF module is 20 \(\times\) 25 mm and the calculated proposed length of the antenna is about 31 mm, the length of the antenna is longer than the width of the RF module. Therefore, the 5-10 mm out of the total length of the antenna should be bent down, as shown in Figure 4. There is a 4 mm notch for pushing the RF module down to the mainboard to secure the RF module from vibration and movement, since the connection between the RF module and the mainboard is very important to communicate and transfer the data to the base station. Therefore, the proposed antenna should have the size of the feeding point as shown in Figure 2, and the height and location of the antenna are fixed as shown in Figure 4 with the polypropylene cover.