Custome plugin for android

Hi I have developed a plugin in Android, now I am trying to integrate into ionic 4 apps, I have followed below steps to integrate the plugin in ionic 4

  1. create wrapper like below
    import { Injectable } from ‘@angular/core’;
    import { Plugin, Cordova, CordovaProperty, cordovaInstance, IonicNativePlugin} from ‘@ionic-native/core’
    export class SyncService extends IonicNativePlugin {
    //provide entry for plugin functions
    static pluginName = ‘synPlguin’;
    static plugin = ‘cordova-aspolar-plugin-signal-strength’;
    static pluginRef = ‘window.plugins.signalStrength’;
    static repo = ‘’;
    static platforms = [‘Android’]

after integrating this, I am getting followed the issue

Uncaught TypeError: Object(…) is not a function

Please help me out how to solve this,
Thank in advance …